MODULATORS OF CAS9 POLYPEPTIDES AND METHODS OF USE THEREOF

CROSS -REFERENCE

[0001] This application claims the benefit of U.S. Provisional Patent Application No.

62/729,295, filed September 10, 2018, which application is incorporated herein by reference in its entirety.

INCORPORATION BY REFERENCE OF SEQUENCE LISTING PROVIDED AS A TEXT FILE

[0002] A Sequence Listing is provided herewith as a text file,“BERK-

396WO_SEQ_LISTING_ST25.txt” created on September 4, 2019 and having a size of 61 KB. The contents of the text file are incorporated by reference herein in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0003] This invention was made with government support under Grant No. HR0011-17-2-0043 awarded by the Defense Advanced Research Projects Agency, and Grant No. 1244557 awarded by the National Science Foundation. The government has certain rights in the invention.

INTRODUCTION

[0004] Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 nucleases, when complexed with a guide RNA, effect genome editing in a sequence-specific manner. RNA- guided Cas9 has proven to be a versatile tool for genome engineering in multiple cell types and organisms.

[0005] There is a need in the art for compositions and methods for controlling genome editing activity of CRISPR/Cas9.

SUMMARY

[0006] The present disclosure provides AcrIIA7 polypeptides, nucleic acids encoding the AcrIIA7 polypeptides, and kits comprising the AcrIIA7 polypeptides and/or nucleic acids encoding the AcrIIA7 polypeptides. The present disclosure provides methods of inhibiting enzymatic activity of a Cas9 polypeptide.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 provides the amino acid sequence of an AcrIIA7 polypeptide. [0008] FIG. 2 provides the nucleotide sequence encoding an AcrIIA7 polypeptide, where the nucleotide sequence is codon optimized for expression in human cells.

[0009] FIG. 3 provides an amino acid sequence of Staphylococcus aureus Cas9.

[0010] FIG. 4 provides an amino acid sequence of Streptococcus pyogenes Cas9.

[0011] FIG. 5 provides an amino acid sequence of Streptococcus thermophilus Cas9.

[0012] FIG. 6 provides an amino acid sequence of Lactobacillus gasseri Cas9.

[0013] FIG. 7 is a schematic depiction of an assay used to identify proteins having anti-CRISPR/Cas9 activity.

[0014] FIG. 8 depicts the effects of various candidate anti-CRISPR proteins (candl through cand8 on Cas9/guide RNA-mediated cleavage of a target nucleic acid encoding a fluorescent protein.

[0015] FIG. 9 depicts the effect of anti-CRISPR protein AcrIIA7 on SauCas9/guide and SpyCas9/guide RNA-mediated cleavage of a target nucleic acid a cell-free in vitro.

[0016] FIG. 10 depicts the effect of anti-CRISPR protein AcrIIA7 on Cas9/guide RNA-mediated

cleavage of a target nucleic acid in a mammalian cell.

[0017] FIG. 11 depicts the effect of anti-CRISPR protein GF31-2 compared to the AcrIIA5 anti-

CRISPR on SauCas9/guide RNA-mediated cleavage of a target nucleic acid at various molar ratios of GF3l-2:SauCas9 and AcrIIA5:SauCas9 in vitro.

[0018] FIG. 12 depicts the effect of a truncated form of anti-CRISPR protein GF31-2 on SauCas9/guide RNA-mediated cleavage of a target nucleic acid at various molar ratios of truncated GF31- 2:SauCas9 in vitro.

[0019] FIG. 13 depicts the effect of a truncated form of anti-CRISPR protein GF31-2 on SpyCas9/guide RNA-mediated cleavage of a target nucleic acid at various molar fold excess of GF31-2 over SpyCas9.

[0020] FIG. 14 depicts the effect of anti-CRISPR protein GF3l-cand2 on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus (SauCas9)/guide RNA-mediated cleavage of a genomic target nucleic acid in a mammalian cell.

[0021] FIG. 15 depicts the effect of anti-CRISPR protein GF3l-2-trunc (gb84; truncated version of GF3l-cand2) on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus (SauCas9)/guide RNA-mediated cleavage of a genomic target nucleic acid in a mammalian cell.

[0022] FIG. 16 depicts the effect of anti-CRISPR protein GF3l-2-hom (gb76; homolog of GF3l-cand2) on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus (SauCas9)/guide RNA-mediated cleavage of a genomic target nucleic acid in a mammalian cell. DEFINITIONS

[0023] The terms“polynucleotide” and“nucleic acid,” used interchangeably herein, refer to a polymeric form of nucleotides of any length, either ribonucleotides or deoxyribonucleotides. Thus, terms“polynucleotide” and“nucleic acid” encompass single-stranded DNA; double- stranded DNA; multi-stranded DNA; single-stranded RNA; double-stranded RNA; multi- stranded RNA; genomic DNA; cDNA; DNA-RNA hybrids; and a polymer comprising purine and pyrimidine bases or other natural, chemically or biochemically modified, non-natural, or derivatized nucleotide bases.

[0024] The term“oligonucleotide” refers to a polynucleotide of between 4 and 100 nucleotides of single- or double-stranded nucleic acid (e.g., DNA, RNA, or a modified nucleic acid).

However, for the purposes of this disclosure, there is no upper limit to the length of an oligonucleotide. Oligonucleotides are also known as“oligomers” or“oligos” and can be isolated from genes, transcribed (in vitro and/or in vivo), or chemically synthesized. The terms “polynucleotide" and "nucleic acid" should be understood to include, as applicable to the embodiments being described, single-stranded (such as sense or antisense) and double-stranded polynucleotides.

[0025] By "hybridizable" or“complementary” or“substantially complementary" it is meant that a nucleic acid (e.g. RNA, DNA) comprises a sequence of nucleotides that enables it to non- covalently bind, i.e. form Watson-Crick base pairs and/or G/U base pairs,“anneal”, or “hybridize,” to another nucleic acid in a sequence-specific, antiparallel, manner (i.e., a nucleic acid specifically binds to a complementary nucleic acid) under the appropriate in vitro and/or in vivo conditions of temperature and solution ionic strength. Standard Watson-Crick base-pairing includes: adenine/adenosine) (A) pairing with thymidine/thymidine (T), A pairing with uracil/ uridine (U), and guanine/guanosine) (G) pairing with cytosine/cytidine (C). In addition, for hybridization between two RNA molecules (e.g., dsRNA), and for hybridization of a DNA molecule with an RNA molecule (e.g., when a DNA target nucleic acid base pairs with a guide RNA, etc.): G can also base pair with U. For example, G/U base-pairing is partially responsible for the degeneracy (i.e., redundancy) of the genetic code in the context of tRNA anti-codon base pairing with codons in rnRNA. Thus, in the context of this disclosure, a G (e.g., of a protein binding segment (e.g., dsRNA duplex) of a guide RNA molecule; of a target nucleic acid (e.g., target DNA) base pairing with a guide RNA) is considered complementary to both a U and to C. For example, when a G/U base-pair can be made at a given nucleotide position of a protein binding segment (e.g., dsRNA duplex) of a guide RNA molecule, the position is not considered to be non-complementary, but is instead considered to be complementary. [0026] Hybridization requires that the two nucleic acids contain complementary sequences, although mismatches between bases are possible. The conditions appropriate for hybridization between two nucleic acids depend on the length of the nucleic acids and the degree of complementarity, variables well known in the art. The greater the degree of complementarity between two nucleotide sequences, the greater the value of the melting temperature (Tm) for hybrids of nucleic acids having those sequences. Typically, the length for a hybridizable nucleic acid is 8 nucleotides or more (e.g., 10 nucleotides or more, 12 nucleotides or more, 15 nucleotides or more, 20 nucleotides or more, 22 nucleotides or more, 25 nucleotides or more, or 30 nucleotides or more).

[0027] It is understood that the sequence of a polynucleotide need not be 100% complementary to that of its target nucleic acid to be specifically hybridizable. Moreover, a polynucleotide may hybridize over one or more segments such that intervening or adjacent segments are not involved in the hybridization event (e.g., a loop structure or hairpin structure, a‘bulge’, and the like). A polynucleotide can comprise 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, 99% or more, 99.5% or more, or 100% sequence complementarity to a target region within the target nucleic acid sequence to which it will hybridize. For example, an antisense nucleic acid in which 18 of 20 nucleotides of the antisense compound are complementary to a target region, and would therefore specifically hybridize, would represent 90 percent complementarity. The remaining noncomplementary nucleotides may be clustered or interspersed with complementary nucleotides and need not be contiguous to each other or to complementary nucleotides. Percent complementarity between particular stretches of nucleic acid sequences within nucleic acids can be determined using any convenient method. Example methods include BLAST programs (basic local alignment search tools) and PowerBLAST programs (Altschul et al., J. Mol. Biol., 1990, 215, 403-410; Zhang and Madden, Genome Res., 1997, 7, 649-656) or by using the Gap program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, Madison Wis.), e.g., using default settings, which uses the algorithm of Smith and Waterman (Adv. Appl. Math., 1981, 2, 482-489).

[0028] The terms "peptide," "polypeptide," and "protein" are used interchangeably herein, and refer to a polymeric form of amino acids of any length, which can include coded and non-coded amino acids, chemically or biochemically modified or derivatized amino acids, and polypeptides having modified peptide backbones.

[0029] "Binding" as used herein (e.g. with reference to an RNA-binding domain of a

polypeptide, binding to a target nucleic acid, and the like) refers to a non-covalent interaction between macromolecules (e.g., between a protein and a nucleic acid; between a guide RNA and a target nucleic acid; and the like). While in a state of non-covalent interaction, the macromolecules are said to be“associated” or“interacting” or“binding” (e.g., when a molecule X is said to interact with a molecule Y, it is meant the molecule X binds to molecule Y in a non- covalent manner). Not all components of a binding interaction need be sequence-specific (e.g., contacts with phosphate residues in a DNA backbone), but some portions of a binding interaction may be sequence-specific. Binding interactions are generally characterized by a dissociation constant (K _d ) of less than 10 ⁶ M, less than 10 ⁷ M, less than 10 ^s M, less than 10 ⁹ M, less than 10 ¹⁰ M, less than 10 ¹¹ M, less than 10 ¹² M, less than 10 ¹³ M, less than 10 ¹⁴ M, or less than 10 ¹⁵ M. "Affinity" refers to the strength of binding, increased binding affinity being correlated with a lower K _d .

[0030] The term "conservative amino acid substitution" refers to the interchangeability in

proteins of amino acid residues having similar side chains. For example, a group of amino acids having aliphatic side chains consists of glycine, alanine, valine, leucine, and isoleucine; a group of amino acids having aliphatic-hydroxyl side chains consists of serine and threonine; a group of amino acids having amide containing side chains consisting of asparagine and glutamine; a group of amino acids having aromatic side chains consists of phenylalanine, tyrosine, and tryptophan; a group of amino acids having basic side chains consists of lysine, arginine, and histidine; a group of amino acids having acidic side chains consists of glutamate and aspartate; and a group of amino acids having sulfur containing side chains consists of cysteine and methionine. Exemplary conservative amino acid substitution groups are: valine-leucine- isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine- valine-glycine, and asparagine- glutamine.

[0031] A polynucleotide or polypeptide has a certain percent "sequence identity" to another polynucleotide or polypeptide, meaning that, when aligned, that percentage of bases or amino acids are the same, and in the same relative position, when comparing the two sequences.

Sequence identity can be determined in a number of different ways. To determine sequence identity, sequences can be aligned using various methods and computer programs (e.g., BLAST, T-COFFEE, MUSCLE, MAFFT, Phyre2, etc.), available over the world wide web at sites including ncbi(dot)nlm(dot)nili(dot)gov/BLAST, ebi(dot)ac(dot)uk/Tools/msa/tcoffee/, ebi(dot)ac(dot)uk/Tools/msa/muscle/, mafft.cbrc(dot)jp/alignment/software/,

www(dot)sbg(dot)bio(dot)ic(dot)ac(dot)uk/~phyre2/. See, e.g., Altschul et al. (1990), J. Mol. Bioi. 215:403-10.

[0032] The terms "DNA regulatory sequences," "control elements," and "regulatory elements," used interchangeably herein, refer to transcriptional and translational control sequences, such as promoters, enhancers, polyadenylation signals, terminators, protein degradation signals, and the like, that provide for and/or regulate transcription of a non-coding sequence (e.g., guide RNA) or a coding sequence (e.g., protein coding) and/or regulate translation of an encoded polypeptide.

[0033] As used herein, a "promoter" is a DNA regulatory region capable of binding RNA

polymerase and initiating transcription of a downstream (3' direction) coding or non-coding sequence. Various promoters, including inducible promoters, may be used to drive the various nucleic acids (e.g., vectors) of the present disclosure.

[0034] "Recombinant," as used herein, means that a particular nucleic acid (DNA or RNA) is the product of various combinations of cloning, restriction, polymerase chain reaction (PCR) and/or ligation steps resulting in a construct having a structural coding or non-coding sequence distinguishable from endogenous nucleic acids found in natural systems. DNA sequences encoding polypeptides can be assembled from cDNA fragments or from a series of synthetic oligonucleotides, to provide a synthetic nucleic acid which is capable of being expressed from a recombinant transcriptional unit contained in a cell or in a cell-free transcription and translation system. Genomic DNA comprising the relevant sequences can also be used in the formation of a recombinant gene or transcriptional unit. Sequences of non-translated DNA may be present 5' or 3' from the open reading frame, where such sequences do not interfere with manipulation or expression of the coding regions, and may indeed act to modulate production of a desired product by various mechanisms (see "DNA regulatory sequences", below). Alternatively, DNA sequences encoding RNA (e.g., guide RNA) that is not translated may also be considered recombinant. Thus, e.g., the term "recombinant" nucleic acid refers to one which is not naturally occurring, e.g., is made by the artificial combination of two otherwise separated segments of sequence through human intervention. This artificial combination is often accomplished by either chemical synthesis means, or by the artificial manipulation of isolated segments of nucleic acids, e.g., by genetic engineering techniques. Such is usually done to replace a codon with a codon encoding the same amino acid, a conservative amino acid, or a non-conservative amino acid. Alternatively, it is performed to join together nucleic acid segments of desired functions to generate a desired combination of functions. This artificial combination is often accomplished by either chemical synthesis means, or by the artificial manipulation of isolated segments of nucleic acids, e.g., by genetic engineering techniques. When a recombinant polynucleotide encodes a polypeptide, the sequence of the encoded polypeptide can be naturally occurring (“wild type”) or can be a variant (e.g., a mutant) of the naturally occurring sequence. Thus, the term

"recombinant" polypeptide does not necessarily refer to a polypeptide whose sequence does not naturally occur. Instead, a“recombinant” polypeptide is encoded by a recombinant DNA sequence, but the sequence of the polypeptide can be naturally occurring (“wild type”) or non- naturally occurring (e.g., a variant, a mutant, etc.). Thus, a "recombinant" polypeptide is the result of human intervention, but may be a naturally occurring amino acid sequence.

[0035] A "vector" or“expression vector” is a replicon, such as plasmid, phage, virus, or cosmid, to which another DNA segment, i.e. an“insert”, may be attached so as to bring about the replication of the attached segment in a cell.

[0036] An“expression cassette” comprises a DNA coding sequence operably linked to a

promoter. "Operably linked" refers to a juxtaposition wherein the components so described are in a relationship permitting them to function in their intended manner. For instance, a promoter is operably linked to a coding sequence if the promoter affects its transcription or expression.

[0037] The terms“recombinant expression vector,” or“DNA construct” are used

interchangeably herein to refer to a DNA molecule comprising a vector and one insert.

Recombinant expression vectors are usually generated for the purpose of expressing and/or propagating the insert(s), or for the construction of other recombinant nucleotide sequences. The insert(s) may or may not be operably linked to a promoter sequence and may or may not be operably linked to DNA regulatory sequences.

[0038] Any given component, or combination of components can be unlabeled, or can be

detectably labeled with a label moiety. In some cases, when two or more components are labeled, they can be labeled with label moieties that are distinguishable from one another.

[0039] General methods in molecular and cellular biochemistry can be found in such standard textbooks as Molecular Cloning: A Laboratory Manual, 3rd Ed. (Sambrook et al., HaRBor Laboratory Press 2001); Short Protocols in Molecular Biology, 4th Ed. (Ausubel et al. eds., John Wiley & Sons 1999); Protein Methods (Bollag et al., John Wiley & Sons 1996); Nonviral Vectors for Gene Therapy (Wagner et al. eds., Academic Press 1999); Viral Vectors (Kaplift & Loewy eds., Academic Press 1995); Immunology Methods Manual (I. Lefkovits ed., Academic Press 1997); and Cell and Tissue Culture: Laboratory Procedures in Biotechnology (Doyle & Griffiths, John Wiley & Sons 1998), the disclosures of which are incorporated herein by reference.

[0040] Before the present invention is further described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. [0041] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges, and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0042] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.

[0043] It must be noted that as used herein and in the appended claims, the singular forms“a,”“an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to“an ACRIIA7 polypeptide” includes a plurality of such polypeptides and reference to“the Cas9 polypeptide” includes reference to one or more Cas9 polypeptides and equivalents thereof known to those skilled in the art, and so forth. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as“solely,”“only” and the like in connection with the recitation of claim elements, or use of a“negative” limitation.

[0044] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. All combinations of the embodiments pertaining to the invention are specifically embraced by the present invention and are disclosed herein just as if each and every combination was individually and explicitly disclosed. In addition, all sub-combinations of the various embodiments and elements thereof are also specifically embraced by the present invention and are disclosed herein just as if each and every such sub-combination was individually and explicitly disclosed herein.

[0045] The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

DETAILED DESCRIPTION

[0046] The present disclosure provides AcrIIA7 polypeptides, nucleic acids encoding the AcrIIA7

polypeptides, and kits comprising the AcrIIA7 polypeptides and/or nucleic acids encoding the AcrIIA7 polypeptides. The present disclosure provides methods of inhibiting an activity of a Cas9 polypeptide.

ACRIIA7 POLYPEPTIDES

[0047] The present disclosure provides AcrIIA7 polypeptides, where such polypeptides are inhibitors of Cas9 activity. An AcrIIA7 polypeptide of the present disclosure can inhibit binding and/or cleavage activity of a Cas9 polypeptide. An AcrIIA7 polypeptide of the present disclosure is also referred to herein as“an anti-CRISPR polypeptide,”“an Acr polypeptide,”“GF31 cand2” or “GF31-2.”

[0048] An AcrIIA7 polypeptide of the present disclosure can comprise an amino acid sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%, amino acid sequence identity to a contiguous stretch of from about 50 amino acids to about 75 amino acids, from about 75 amino acids to about 100 amino acids, from about 100 amino acids to about 125 amino acids, from about 125 amino acids to about 150 amino acids, or from about 150 amino acids to about 187 amino acids, of the AcrIIA7 amino acid sequence depicted in FIG. 1 (SEQ ID NO:l).

[0049] In some cases, an AcrIIA7 polypeptide of the present disclosure comprises an amino acid

sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the AcrIIA7 amino acid sequence depicted in FIG. 1 (SEQ ID NO:l).

[0050] An AcrIIA7 polypeptide of the present disclosure can have a length of from about 150 amino acids to about 187 amino acids. For example, an AcrIIA7 polypeptide of the present disclosure can have a length of from about 150 amino acids to about 155 amino acids, from about 155 amino acids to about 160 amino acids, from about 160 amino acids to about 165 amino acids, from about 165 amino acids to about 170 amino acids, from about 170 amino acids to about 175 amino acids, from about 175 amino acids to about 180 amino acids, or from about 180 amino acids to about 187 amino acids. In some cases, an AcrIIA7 polypeptide of the present disclosure can have a length of less than 150 amino acids. For example, in some cases, an AcrIIA7 polypeptide of the present disclosure has a length of from about 75 amino acids to about 150 amino acids. For example, in some cases, an AcrIIA7 polypeptide of the present disclosure has a length of from about 75 amino acids to about 100 amino acids, from about 100 amino acid to about 125 amino acids, or from about 125 amino acids to about 150 amino acids.

[0051] In some cases, an AcrIIA7 polypeptide of the present disclosure comprises an amino acid

sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the AcrIIA7 amino acid sequence depicted in FIG. 1; and has a length of from about 150 amino acids to about 155 amino acids, from about 155 amino acids to about 160 amino acids, from about 160 amino acids to about 165 amino acids, from about 165 amino acids to about 170 amino acids, from about 170 amino acids to about 175 amino acids, from about 175 amino acids to about 180 amino acids, or from about 180 amino acids to about 187 amino acids.

[0052] In some cases, an Acr polypeptide of the present disclosure lacks the N-terminal 50 to 59 amino acids of the Acr amino acid sequence set forth in SEQ ID NO:l. In some cases, an Acr polypeptide of the present disclosure lacks the following amino acid sequence:

MRETIQRLLASNLSSNSIALATGVSQAVISKLRNAKKEIGNLSLNSAEKLYNYQKGLEV (SEQ ID NO: 11). In some cases, an Acr polypeptide of the present disclosure comprises an amino acid sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95%, to the amino acid sequence set forth in SEQ ID NO:l; lacks the N-terminal 50 to 59 amino acids of the Acr amino acid sequence set forth in SEQ ID NO:l; and has a length of about 128 amino acids (e.g., has a length of from 125 amino acids to 134 amino acids; e.g., has a length of 125 amino acids, 126 amino acids, 127 amino acids, 128 amino acids, 129 amino acids, 130 amino acids, 131 amino acids, 132 amino acids, 133 amino acids, or 134 amino acids).

[0053] In some cases, an Acr polypeptide of the present disclosure comprises an amino acid sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the following amino acid sequence:

MNKSIEIKDQNNIVLIDSLGQFFTDIENDNNGRYNIDYVLLNEVEHDNGNTYYEVGMYR TEEVPFSDKVTQDNVELLEDKWLQIDQQGESYVESIFFENEEDAREYIKLVLKGHETFEE TAKAIGVIK (SEQ ID NO: 12); and has a length of about 128 amino acids (e.g., e.g., has a length of from 125 amino acids to 134 amino acids; e.g., has a length of 125 amino acids, 126 amino acids, 127 amino acids, 128 amino acids, 129 amino acids, 130 amino acids, 131 amino acids, 132 amino acids, 133 amino acids, or 134 amino acids). An Acr having the amino acid sequence set forth in SEQ ID NO:l2 is referred to in the Examples as“GF3l-2-trunc.”

[0054] In some cases, an Acr polypeptide of the present disclosure comprises an amino acid sequence having at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the following amino acid sequence:

MNELNNKMIEDVVLGEVELIEDLGQYFIDIEGDYEYNVEFATLSEVDYKVCALYEVATS KTYEVPYHDKFEKEDMKFFYDKWFEKDQQEETYIESVFFVNREDAESYIKDVFKGKES LTEVAAEIGYFE (SEQ ID NO:49); and has a length of about 129 amino acids (e.g., e.g., has a length of from 125 amino acids to 134 amino acids; e.g., has a length of 125 amino acids, 126 amino acids, 127 amino acids, 128 amino acids, 129 amino acids, 130 amino acids, 131 amino acids, 132 amino acids, 133 amino acids, or 134 amino acids). An Acr having the amino acid sequence set forth in SEQ ID NO:49 is referred to in the Examples as“GF31-2 hom.”

[0055] In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits binding and/or cleavage activity of a Cas9 polypeptide by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the binding and/or cleavage activity of the Cas9 polypeptide in the absence of the AcrIIA7 polypeptide (i.e., where the Cas9 polypeptide is not contacted with the AcrIIA7 polypeptide).

[0056] In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits binding and/or cleavage activity of a Cas9/guide RNA complex by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the binding and/or cleavage activity of the Cas9/guide RNA complex in the absence of the AcrIIA7 polypeptide (i.e., where the Cas9/guide RNA complex is not contacted with the AcrIIA7 polypeptide).

[0057] In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits cleavage activity of a

Cas9/guide RNA complex by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the cleavage activity of the Cas9/guide RNA complex in the absence of the AcrIIA7 polypeptide (i.e., where the Cas9/guide RNA complex is not contacted with the AcrIIA7 polypeptide).

[0058] In some cases, an Acr polypeptide of the present disclosure inhibits cleavage activity of a Cas9 polypeptide present in a Cas9/guide RNA complex by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the cleavage activity of the Cas9 polypeptide in the absence of the Acr polypeptide, when the molar ratio of Acr to Cas9 polypeptide is at least 2:1, at least 5:1, or at least 10:1. In some cases, an Acr polypeptide of the present disclosure inhibits cleavage activity of a Cas9 polypeptide present in a Cas9/guide RNA complex by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the cleavage activity of the Cas9 polypeptide in the absence of the Acr polypeptide, when the molar ratio of Acr to Cas9 polypeptide is from about 2:1 to about 5:1, from about 5:1 to about 10:1, from about 10:1 to about 20:1, or from about 20:1 to about 40:1.

[0059]“Binding” activity of a Cas9/guide RNA complex refers to binding of the Cas9/guide RNA

complex to a target nucleic acid, where the target nucleic acid comprises a nucleotide sequence that has complementarity to a target-binding nucleotide sequence in the guide RNA.

[0060]“Cleavage” activity of a Cas9/guide RNA complex refers to generation by the Cas9/guide RNA complex of a single-strand or double-strand break in a target nucleic acid.

[0061] In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits binding and/or cleavage activity of a Cas9 polypeptide having at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Staphylococcus aureus Cas9 amino acid sequence provided in FIG. 2.

[0062] In some cases, an AcrIIA7 polypeptide of the present disclosure does not substantially inhibit activity (e.g., cleavage activity) of a Cas9 having at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Lactobacillus gasseri amino acid sequence provided in FIG. 6.

[0063] In some cases, an AcrIIA7 polypeptide of the present disclosure does not substantially inhibit cleavage activity of Streptococcus pyogenes Cas9. For example, in some cases, an AcrIIA7 polypeptide of the present disclosure does not substantially inhibit cleavage activity of a Cas9/guide RNA complex, where the Cas9 present in the Cas9/guide RNA complex comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Streptococcus pyogenes Cas9 amino acid sequence provided in FIG. 4. In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits cleavage activity of a Cas9/guide RNA complex by no more than 20%, no more than 15%, no more than 10%, no more than 5%, no more than 2%, or no more than 1%, compared to the cleavage activity of the Cas9/guide RNA complex in the absence of the AcrIIA7 polypeptide, where the Cas9 present in the Cas9/guide RNA complex comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Streptococcus pyogenes Cas9 amino acid sequence provided in FIG. 4. In some cases, an AcrIIA7 polypeptide of the present disclosure inhibits cleavage activity of a CasSVguide RNA complex by less than 20%, less than 15%, less than 10%, less than 5%, less than 2%, or less than 1%, compared to the cleavage activity of the CasSVguide RNA complex in the absence of the AcrIIA7 polypeptide, where the Cas9 present in the CasSVguide RNA complex comprises an amino acid sequence having at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Streptococcus pyogenes Cas9 amino acid sequence provided in FIG. 4.

[0064] Whether an AcrIIA7 polypeptide inhibits cleavage activity of a given Cas9 polypeptide present in a Cas9/guide RNA complex can be readily determined. For example, the effect of an AcrIIA7 polypeptide of the present disclosure on cleavage of a target DNA by a Cas9/guide RNA complex can be tested in a cell-free system in vitro, as described in the Examples section. For example, a target DNA is mixed in vitro with: a) a complex of Cas9 and a guide RNA, where the guide RNA comprises both a nucleotide sequence (tracrRNA) that activates the Cas9 polypeptide and a nucleotide sequence (crRNA) that binds to the target DNA; and b) an AcrIIA7 polypeptide. Production of cleavage products of action of the Cas9 on the target DNA can be detected by resolving the cleavage products on a 1 % agarose cell and staining the resolved cleavage products.

[0065] As another example, the effect of an AcrIIA7 polypeptide of the present disclosure on cleavage of a target DNA by a Cas9/guide RNA complex can be tested in a cell. For example, a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide and a nucleic acid comprising a nucleotide sequence encoding a reporter (e.g., a fluorescent protein such as a green fluorescent protein) can be integrated into the genome of a mammalian cell (e.g., 293 cells, or other mammalian cell line), generating a reporter cell; and a ribonucleoprotein (RNP) complex comprising a Cas9 polypeptide and a guide RNA targeting the nucleotide sequence encoding the reporter is introduced into the reporter cell. Inhibition of gene editing of the reporter can be determined by detecting the reporter. For example, where the reporter is a fluorescent protein, fluorescence activated cell sorting (FACS) can be used to determine whether gene editing has been inhibited. As another example, a mixture of a Cas9/guide RNA complex and AcrIIA7 polypeptide can be introduced into a mammalian cell line, and the effect of the AcrIIA7 polypeptide on the ability of the Cas9/guide RNA complex to carry out gene editing can be determined by analyzing production of a gene product encoded by a nucleotide sequence targeted by the guide RNA.

Covalently linked non-peptidic moiety

[0066] In some cases, an AcrIIA7 polypeptide of the present disclosure comprises a non-peptidic moiety covalently linked to the AcrIIA7 polypeptide. The covalently linked non-peptidic moiety can confer a desirable attribute (e.g., increased protease resistance, increased membrane permeability, increased in vivo half-life, increased in vivo stability, increased bioavailability), without substantially altering the ability of the linked AcrIIA7 polypeptide to inhibit Cas9 activity.

[0067] In some cases, the non-peptidic moiety confers increased in vivo half-life on the linked AcrIIA7 polypeptide, compared to the in vivo half-life of the AcrIIA7 not comprising the non-peptidic moiety. For example, in some cases, the in vivo half-life of an AcrIIA7 polypeptide comprising a covalently linked non-peptidic moiety is at least 10%, at least 25%, at least 50%, at least 2-fold, at least 5-fold, or at least lO-fold, greater than the in vivo half-life of the AcrIIA7 polypeptide not comprising the non-peptidic moiety. For example, in some cases, the non-peptidic moiety confers an increase in half-life of the linked AcrIIA7 polypeptide in circulation in an animal. In some cases, the non-peptidic moiety confers increased in vivo stability on the linked AcrIIA7 polypeptide, compared to the in vivo stability of the AcrIIA7 polypeptide not comprising the non-peptidic moiety. For example, in some cases, the in vivo stability of an AcrIIA7 polypeptide comprising a covalently linked non-peptidic moiety is at least 10%, at least 25%, at least 50%, at least 2-fold, at least 5-fold, or at least lO-fold, greater than the in vivo stability of the AcrIIA7 polypeptide not comprising the non-peptidic moiety. In some cases, the non-peptidic moiety confers increased bioavailability on the linked AcrIIA7 polypeptide, compared to the bioavailability of the AcrIIA7 polypeptide not comprising the non-peptidic moiety. For example, in some cases, the bioavailability of an AcrIIA7 polypeptide comprising a covalently linked non- peptidic moiety is at least 10%, at least 25%, at least 50%, at least 2-fold, at least 5-fold, or at least lO-fold, greater than the bioavailability of the AcrIIA7 polypeptide not comprising the non- peptidic moiety.

[0068] Suitable non-peptidic moieties include, but are not limited to, lipids and non-peptidic polymers.

Suitable non-peptidic moieties include, but are not limited to, poly(ethylene glycol), polysialic acid, hydroxyethyl starch (F1ES), a dendrimer, a nanoparticle, and a liposome.

[0069] In some cases, a non-peptidic moiety covalently linked to an AcrIIA7 polypeptide of the present disclosure is a polymer. Polymers may contain one more of the following polyesters:

homopolymers including glycolic acid units, referred to herein as“PGA”; lactic acid units, such as poly-L-lactic acid, poly-D-lactic acid, poly-D,L-lactic acid, poly-L-lactide, poly-D-lactide, and poly-D,L-lactide, collectively referred to herein as“PLA”; caprolactone units, such as poly(caprolactone), collectively referred to herein as“PCL”; copolymers including lactic acid and glycolic acid units, such as various forms of poly(lactic acid-co-glycolic acid) and poly(lactide-co-glycolide) characterized by the ratio of lactic acid:glycolic acid, collectively referred to herein as“PLGA”; and poly acrylates, and derivatives thereof. Exemplary polymers also include copolymers of polyethylene glycol (PEG) and the aforementioned polyesters, such as various forms of PLGA-PEG or PLA-PEG copolymers, collectively referred to herein as "PEGylated polymers". In certain cases, the PEG region can be covalently associated with polymer to yield "PEGylated polymers" by a cleavable linker.

[0070] An AcrIIA7 polypeptide of the present disclosure may include one or more covalently linked hydrophilic polymers. Hydrophilic polymers include cellulosic polymers such as starch and polysaccharides; hydrophilic polypeptides; poly (amino acids) such as poly-L-glutamic acid (PGS), gamma-polyglutamic acid, poly-L-aspartic acid, poly-L-serine, or poly-L-lysine;

polyalkylene glycols and polyalkylene oxides such as polyethylene glycol (PEG), polypropylene glycol (PPG), and poly (ethylene oxide) (PEO); poly(oxyethylated polyol); poly(olefinic alcohol) ; polyvinylpyrrolidone) ; poly (hydroxy alky lmethacrylamide) ;

poly(hydroxyalkylmethacrylate); poly(saccharides); poly(hydroxy acids); poly(vinyl alcohol); polyoxazoline; and copolymers thereof.

[0071] An AcrIIA7 polypeptide of the present disclosure may include one or more covalently linked hydrophobic polymers. Examples of suitable hydrophobic polymers include polyhydroxyacids such as poly (lactic acid), poly (glycolic acid), and poly(lactic acid-co-glycolic acids);

polyhydroxy alkanoates such as poly3-hydroxybutyrate or poly4-hydroxybutyrate;

polycaprolactones; poly(orthoesters); polyanhydrides; poly(phosphazenes); poly(lactide-co- caprolactones); polycarbonates such as tyrosine polycarbonates; polyamides (including synthetic and natural polyamides), polypeptides, and poly(amino acids); polyesteramides; polyesters; poly(dioxanones); poly(alkylene alkylates); hydrophobic polyethers; polyurethanes;

polyetheresters; polyacetals; poly cyanoacrylates; poly acrylates; polymethylmethacrylates; polysiloxanes; poly(oxyethylene)/poly(oxypropylene) copolymers; polyketals; polyphosphates; polyhydroxy valerates; polyalkylene oxalates; polyalkylene succinates; poly(maleic acids), as well as copolymers thereof.

[0072] An AcrIIA7 polypeptide of the present disclosure may include one or more covalently linked biodegradable polymers. Suitable biodegradable polymers can include polyamides,

polycarbonates, poly alky lenes, polyalkylene glycols, polyalkylene oxides, polyalkylene terepthalates, polyvinyl alcohols, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyvinylpyrrolidone, polyglycolides, polysiloxanes, polyurethanes and copolymers thereof, alkyl cellulose such as methyl cellulose and ethyl cellulose, hydroxyalkyl celluloses such as hydroxypropyl cellulose, hydroxy-propyl methyl cellulose, and hydroxybutyl methyl cellulose, cellulose ethers, cellulose esters, nitro celluloses, cellulose acetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate phthalate, carboxylethyl cellulose, cellulose triacetate, cellulose sulphate sodium salt, polymers of acrylic and methacrylic esters such as poly (methyl methacrylate), poly(ethylmethacrylate), poly(butylmethacrylate), poly(isobutylmethacrylate), poly (hexlmethacry late), poly(isodecylmethacrylate), poly(lauryl methacrylate), poly (phenyl methacrylate), poly (methyl acrylate), poly (isopropyl acrylate), poly(isobutyl acrylate), poly(octadecyl acrylate), polyethylene, polypropylene poly(ethylene glycol), poly (ethylene oxide), poly (ethylene terephthalate), poly (vinyl alcohols), poly (vinyl acetate, poly vinyl chloride polystyrene and polyvinylpryrrolidone, derivatives thereof, linear and branched copolymers and block copolymers thereof, and blends thereof. Exemplary biodegradable polymers include polyesters, poly (ortho esters), poly (ethylene imines), poly(caprolactones), poly(hydroxyalkanoates), poly(hydroxy valerates), poly anhydrides, poly(acrylic acids), polyglycolides, poly (urethanes), polycarbonates, polyphosphate esters, polyphosphazenes, derivatives thereof, linear and branched copolymers and block copolymers thereof, and blends thereof. In some embodiments the particle contains biodegradable polyesters or polyanhydrides such as poly(lactic acid), poly(glycolic acid), and poly(lactic-co-glycolic acid).

Fusion polypeptides

[0073] In some cases, an AcrIIA7 polypeptide is a fusion AcrIIA7 polypeptide. The present disclosure provides a fusion polypeptide (an“AcrIIA7 fusion polypeptide”) comprising: a) an AcrIIA7 polypeptide of the present disclosure; and b) a heterologous fusion partner. The heterologous fusion partner can provide one or more desirable attributes (where such attributes include, e.g., as increased protease resistance, increased membrane permeability, or increased half-life, increased nuclear localization, and the like) without substantially altering the ability of the linked AcrIIA7 polypeptide to inhibit Cas9 activity. A fusion polypeptide comprising: a) an AcrIIA7 polypeptide of the present disclosure; and b) a heterologous fusion partner is also referred to herein as an“AcrIIA7 fusion polypeptide.” A fusion polypeptide of the present disclosure can comprise two or more heterologous fusion partners.

[0074] Suitable heterologous fusion partners include, but are not limited to, a nuclear localization

signal; a chloroplast transit peptide; an endosomal escape peptide; an epitope tag; a polypeptide that provides for ease of purification; a detectable protein; a protein that provides for increased in vivo half-life; and the like.

[0075] Suitable heterologous fusion partners include a hydroxine-binding protein, transthyretin, al-acid glycoprotein (AAG), transferrin, fibrinogen, albumin, an immunoglobulin, a-2-macroglobulin, a lipoprotein, and a fragment of any of the foregoing. Suitable heterologous fusion partners include a fluorescent protein, e.g., a green fluorescent protein (GFP), a yellow fluorescent protein, a red fluorescent protein a cyan fluorescent protein, and the like. Suitable heterologous fusion partners include, e.g., a poly(histidine) tag (e.g., a 6XHis tag); a hemagglutinin (HA) tag; a FFAG tag; a Myc tag; and the like. [0076] In some cases, a fusion polypeptide of the present disclosure comprises an AcrIIA7 polypeptide fused to a nuclear localization signal (NLS) (e.g., in some cases 2 or more, 3 or more, 4 or more, or 5 or more NLSs). Thus, in some cases, a fusion AcrIIA7 polypeptide includes one or more NLSs (e.g., 2 or more, 3 or more, 4 or more, or 5 or more NLSs). In some cases, one or more NLSs (2 or more, 3 or more, 4 or more, or 5 or more NLSs) are positioned at or near (e.g., within 50 amino acids of) the N-terminus and/or the C-terminus of the AcrIIA7 polypeptide. In some cases, one or more NLSs (2 or more, 3 or more, 4 or more, or 5 or more NLSs) are positioned at or near (e.g., within 50 amino acids of) the N-terminus of the AcrIIA7 polypeptide. In some cases, one or more NLSs (2 or more, 3 or more, 4 or more, or 5 or more NLSs) are positioned at or near (e.g., within 50 amino acids of) the C-terminus of the AcrIIA7 polypeptide. In some cases, one or more NLSs (3 or more, 4 or more, or 5 or more NLSs) are positioned at or near (e.g., within 50 amino acids of) both the N-terminus and the C-terminus of the AcrIIA7 polypeptide. In some cases, an NLS is positioned at the N-terminus and an NLS is positioned at the C-terminus of the AcrIIA7 polypeptide.

[0077] Non-limiting examples of NLSs include an NLS sequence derived from: the NLS of the SV40 virus large T-antigen, having the amino acid sequence PKKKRKV (SEQ ID NO:47); the NLS from nucleoplasmin (e.g., the nucleoplasmin bipartite NLS with the sequence

KRPAATKKAGQAKKKK (SEQ ID NO: 13)); the c-myc NLS having the amino acid sequence PAAKRVKLD (SEQ ID NO: 14) or RQRRNELKRSP (SEQ ID NO: 15); the hRNPAl M9 NLS having the sequence NQS SNFGPMKGGNFGGRS SGPY GGGGQ YF AKPRN QGGY (SEQ ID NO: 16); the sequence RMRIZFKNKGKDT AELRRRR VE V S VELRKAKKDEQILKRRN V (SEQ ID NO: 17) of the IBB domain from importin-alpha; the sequences VSRKRPRP (SEQ ID NO: 18) and PPKKARED (SEQ ID NO: 19) of the myoma T protein; the sequence PQPKKKPL (SEQ ID NO:20) of human p53; the sequence SALIKKKKKMAP (SEQ ID NO:2l) of mouse c- abl IV; the sequences DRLRR (SEQ ID NO:22) and PKQKKRK (SEQ ID NO:23) of the influenza virus NS1; the sequence RKLKKKIKKL (SEQ ID NO:24) of the Hepatitis virus delta antigen; the sequence REKKKFLKRR (SEQ ID NO:25) of the mouse Mxl protein; the sequence KRKGDEVDGVDEVAKKKSKK (SEQ ID NO:26) of the human poly(ADP-ribose) polymerase; and the sequence RKCLQAGMNLEARKTKK (SEQ ID NO:27) of the steroid hormone receptors (human) glucocorticoid.

[0078] An AcrIIA7 fusion polypeptide of the present disclosure can include, as the fusion partner, a "Protein Transduction Domain" or PTD (also known as a CPP - cell penetrating peptide).

Examples of PTDs include but are not limited to a minimal undecapeptide protein transduction domain (corresponding to residues 47-57 of HIV-l TAT comprising YGRKKRRQRRR; SEQ ID NO:32); a polyarginine sequence comprising a number of arginines sufficient to direct entry into a cell (e.g., 3, 4, 5, 6, 7, 8, 9, 10, or 10-50 arginines); a VP22 domain (Zender et al. (2002) Cancer Gene Ther. 9(6):489-96); an Drosophila Antennapedia protein transduction domain (Noguchi et al. (2003) Diabetes 52(7): 1732-1737); a truncated human calcitonin peptide (Trehin et al. (2004) Pharm. Research 21:1248-1256); polylysine (Wender et al. (2000) Proc. Natl.

Acad. Sci. USA 97:13003-13008); RRQRRTSKLMKR (SEQ ID NO:28); Transportan

GWTLNSAGYLLGKINLKALAALAKKIL (SEQ ID NO:29);

KALAWEAKLAKALAKALAKHLAKALAKALKCEA (SEQ ID NO:30); and

RQIKIWFQNRRMKWKK (SEQ ID NO:3l). Exemplary PTDs include but are not limited to, YGRKKRRQRRR (SEQ ID NO:32), RKKRRQRRR (SEQ ID NO:33); an arginine

homopolymer of from 3 arginine residues to 50 arginine residues; Exemplary PTD domain amino acid sequences include, but are not limited to, any of the following: YGRKKRRQRRR (SEQ ID NO:32); RKKRRQRR (SEQ ID NO:34); YARAAARQARA (SEQ ID NO:35);

THRLPRRRRRR (SEQ ID NO:36); and GGRRARRRRRR (SEQ ID NO:37). In some embodiments, the PTD is an activatable CPP (ACPP) (Aguilera et al. (2009) Integr Biol ( Camb) June; 1(5-6): 371-381).

[0079] In some cases, an AcrIIA7 fusion polypeptide of the present disclosure comprises a linker

between the AcrIIA7 polypeptide and the fusion partner. Suitable linkers include polypeptides of between 4 amino acids and 40 amino acids in length, or between 4 amino acids and 25 amino acids in length. These linkers can be produced by using synthetic, linker-encoding

oligonucleotides to couple the proteins, or can be encoded by a nucleic acid sequence encoding the fusion protein. Peptide linkers with a degree of flexibility can be used. The linking peptides may have virtually any amino acid sequence, bearing in mind that the preferred linkers will have a sequence that results in a generally flexible peptide. The use of small amino acids, such as glycine and alanine, are of use in creating a flexible peptide. The creation of such sequences is routine to those of skill in the art. A variety of different linkers are commercially available and are considered suitable for use. In some cases, the linker is proteolytically cleavable.

[0080] Examples of linker polypeptides include glycine polymers (G) _n , glycine-serine polymers

(including, for example, (GS)„, GSGGS _n (SEQ ID NO:38), GGSGGS _n (SEQ ID NO:39), and GGGGS _n (SEQ ID NO:40), where n is an integer of at least one), glycine-alanine polymers, alanine-serine polymers. Exemplary linkers can comprise amino acid sequences including, but not limited to, GGSG (SEQ ID NO:4l), GGSGG (SEQ ID NO:42), GSGSG (SEQ ID NO:43), GSGGG (SEQ ID NO:44), GGGSG (SEQ ID NO:45), GSSSG (SEQ ID NO:46), and the like.

[0081] An AcrIIA7 fusion polypeptide of the present disclosure can also comprise a covalently linked non-peptidic moiety, where suitable non-peptidic moieties are discussed above. NUCLEIC ACIDS AND RECOMBINANT EXPRESSION VECTORS

[0082] The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a recombinant expression vector comprising a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure. The present disclosure provides a recombinant expression vector comprising a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure.

[0083] The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. In some cases, the nucleic acid is RNA. In some cases, the nucleic acid is DNA. The present disclosure provides a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure. In some cases, the nucleic acid is RNA. In some cases, the nucleic acid is DNA.

[0084] In some cases, a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure is codon optimized. This type of optimization can entail a mutation of an AcrIIA7-encoding nucleotide sequence to mimic the codon preferences of the intended host organism or cell while encoding the same protein. Thus, the codons can be changed, but the encoded protein remains unchanged. For example, if the intended target cell was a human cell, a human codon-optimized AcrIIA7-encoding nucleotide sequence could be used. As another non-limiting example, if the intended host cell were a mouse cell, then a mouse codon-optimized AcrIIA7-encoding nucleotide sequence could be generated. As another non-limiting example, if the intended host cell were a plant cell, then a plant codon-optimized AcrIIA7-encoding nucleotide sequence could be generated. As another non-limiting example, if the intended host cell were an insect cell, then an insect codon-optimized AcrIIA7-encoding nucleotide sequence could be generated. A non limiting example of a codon-optimized AcrIIA7-encoding nucleotide sequence is provided in FIG. 2.

[0085] As one example, a human codon-optimized nucleotide sequence encoding a truncated Acr (an Acr lacking the N-terminal 59 amino acids, as described above, is as follows:

[0086] ATGAACAAATCTATCGAGATCAAAGATCAAAACAACATAGTCCTGATTGACAGTCT TGGACAGTTCTTTACAGACATCGAAAATGATAATAACGGTCGATATAACATCGACTA CGTGCTGCTCAACGAGGTAGAACACGACAATGGCAACACGTACTACGAAGTGGGCA TGTATCGGACCGAAGAGGTACCCTTTTCCGACAAAGTGACCCAGGACAATGTAGAA CTTCTGGAGGATAAATGGCTGCAAATAGATCAACAAGGCGAGAGCTATGTTGAAAG CATTTTTTTTGAGAACGAAGAGGACGCTAGAGAATATATTAAGTTGGTCCTGAAGGG TCATGAGACATTTGAGGAAACGGCTAAAGCAATCGGAGTCATCAAGTAA (SEQ ID NO:48).

[0087] As another example, a human codon optimized nucleotide sequence encoding the Acr referred to above as“GF31-2 horn” is as follows.

[0088] ATGAACGAACTCAATAATAAGATGATCGAAGACGTTGTCCTCGGAGAGGTGGAGTT GAT AGAGG ATCTCGGT C AGT ATTTC AT AG AT AT AGA AGGAGATT ACGA AT AT A ACG TAGAATTTGCTACGCTCAGCGAAGTAGACTATAAAGTCTGTGCTTTGTATGAAGTAG CGACGAGT A AGACTT ACGAGGTGCCGT ACC AT GAT A A ATTGGAGA AGGA AGAT ATG AAGCTGTTCTACGATAAGTGGCTGGAGAAAGACCAACAGGAAGAAACGTACATAGA

AGGAAAAGAGTCCCTGACCGAGGTCGCGGCCGAGATTGGTTACTTTGAGTAA (SEQ ID NO:50).

[0089] In some cases, the nucleotide sequence encoding an AcrIIA7 polypeptide of the present

disclosure, or encoding an AcrIIA7 fusion polypeptide of the present disclosure, is operably linked to one or more of a promoter, an enhancer, an internal ribosomal entry site, and a transcription termination signal.

[0090] In some cases, the nucleotide sequence encoding an AcrIIA7 polypeptide of the present

disclosure, or encoding an AcrIIA7 fusion polypeptide of the present disclosure, is operably linked to a transcriptional control element. In some cases, the transcriptional control element is a transcriptional control element that is functional in a eukaryotic cell.

[0091] The transcriptional control element can be a promoter. In some cases, the promoter is a

constitutively active promoter. In some cases, the promoter is a regulatable promoter. In some cases, the promoter is an inducible promoter. In some cases, the promoter is a tissue-specific promoter. In some cases, the promoter is a cell type-specific promoter. In some cases, the transcriptional control element (e.g., the promoter) is functional in a targeted cell type or targeted cell population. For example, in some cases, the transcriptional control element can be functional in a T cell, a B cell, a hematopoietic stem cell, a liver cell, a lung cell, a muscle cell (e.g., a cardiac muscle cell; a skeletal muscle cell), a retinal cell, or other targeted cell.

[0092] A suitable promoter can be a constitutively active promoter (i.e., a promoter that is constitutively in an active/”ON” state). A suitable promoter may be an inducible promoter (i.e., a promoter whose state, active/”ON” or inactive/ OFF”, is controlled by an external stimulus, e.g., the presence of a particular temperature, compound, or protein). A suitable promoter can be a spatially restricted promoter (i.e., transcriptional control element, enhancer, etc.)(e.g., tissue specific promoter, cell type specific promoter, etc.), and it may be a temporally restricted promoter (i.e., the promoter is in the“ON” state or“OFF” state during specific stages of embryonic development or during specific stages of a biological process).

[0093] Suitable promoters can be derived from viruses and can therefore be referred to as viral

promoters, or they can be derived from any organism, including prokaryotic or eukaryotic organisms. Suitable promoters can be used to drive expression by any RNA polymerase (e.g., pol I, pol II, pol III). Exemplary promoters include, but are not limited to the SV40 early promoter, mouse mammary tumor virus long terminal repeat (LTR) promoter; adenovirus major late promoter (Ad MLP); a herpes simplex virus (F1SV) promoter, a cytomegalovirus (CMV) promoter such as the CMV immediate early promoter region (CMVIE), a Rous sarcoma virus (RSV) promoter, a human U6 small nuclear promoter (U6) (Miyagishi et al., Nature

Biotechnology 20, 497 - 500 (2002)), an enhanced U6 promoter (e.g., Xia et al., Nucleic Acids Res. 2003 Sep 1 ;31 (17)), a human Hl promoter (Hl), and the like.

[0094] Inducible promoters suitable for use include any inducible promoter described herein or known to one of ordinary skill in the art. Examples of inducible promoters include, without limitation, chemically/biochemically-regulated and physically-regulated promoters such as alcohol- regulated promoters, tetracycline -regulated promoters (e.g., anhydrotetracycline (aTc)- responsive promoters and other tetracycline-responsive promoter systems, which include a tetracycline repressor protein (tetR), a tetracycline operator sequence (tetO) and a tetracycline transactivator fusion protein (tTA)), steroid-regulated promoters (e.g., promoters based on the rat glucocorticoid receptor, human estrogen receptor, moth ecdysone receptors, and promoters from the steroid/retinoid/thyroid receptor superfamily), metal-regulated promoters (e.g., promoters derived from metallothionein (proteins that bind and sequester metal ions) genes from yeast, mouse and human), pathogenesis-regulated promoters (e.g., induced by salicylic acid, ethylene or benzothiadiazole (BTF1)), temperature/heat-inducible promoters (e.g., heat shock promoters), and light-regulated promoters (e.g., light responsive promoters from plant cells).

[0095] In some cases, the promoter is a spatially restricted promoter (i.e., cell type specific promoter, tissue specific promoter, etc.) such that in a multi-cellular organism, the promoter is active (i.e., “ON”) in a subset of specific cells. Spatially restricted promoters may also be referred to as enhancers, transcriptional control elements, control sequences, etc. Any convenient spatially restricted promoter may be used as long as the promoter is functional in the targeted host cell (e.g., eukaryotic cell).

[0096] In some cases, the promoter is a reversible promoter. Suitable reversible promoters, including reversible inducible promoters are known in the art. Such reversible promoters may be isolated and derived from any of a variety of organisms. Modification of reversible promoters derived from a first organism for use in a second (different) organism is well known in the art. Such reversible promoters, and systems based on such reversible promoters but also comprising additional control proteins, include, but are not limited to, alcohol regulated promoters (e.g., alcohol dehydrogenase I (alcA) gene promoter, promoters responsive to alcohol transactivator proteins (AlcR), etc.), tetracycline regulated promoters, (e.g., promoter systems including Tet Activators, TetON, TetOFF, etc.), steroid regulated promoters (e.g., rat glucocorticoid receptor promoter systems, human estrogen receptor promoter systems, retinoid promoter systems, thyroid promoter systems, ecdysone promoter systems, mifepristone promoter systems, etc.), metal regulated promoters (e.g., metallothionein promoter systems, etc.), pathogenesis- related regulated promoters (e.g., salicylic acid regulated promoters, ethylene regulated promoters, benzothiadiazole regulated promoters, etc.), temperature regulated promoters (e.g., heat shock inducible promoters (e.g., F1SP-70, F1SP-90, soybean heat shock promoter, etc.), light regulated promoters, synthetic inducible promoters, and the like. A suitable promoter can include elements that are responsive to transactivation, e.g., hypoxia response elements, Gal4 response elements, lac repressor response element, and small molecule control systems such as tetracycline-regulated systems and the RU-486 system (see, e.g., Gossen & Bujard, 1992, Proc. Natl. Acad. Sci. USA, 89:5547; Oligino et al., 1998, Gene Ther., 5:491-496; Wang et al., 1997, Gene Ther., 4:432-441; Neering et al., 1996, Blood, 88:1147-55; and Rendahl et al., 1998, Nat. Biotechnol., 16:757-761).

[0097] For illustration purposes, examples of spatially restricted promoters include, but are not limited to, neuron-specific promoters, adipocyte-specific promoters, cardiomyocyte-specific promoters, smooth muscle-specific promoters, photoreceptor-specific promoters, etc. In some cases, the promoter is an insect-specific promoter. In some cases, the promoter is a plant-specific promoter. In some cases, the promoter is a protozoan-specific promoter.

[0098] In some cases, the promoter is a plant-specific promoter. Examples of plant promoters include, but are not limited to, a cauliflower mosaic virus (CaMV) promoter, a nopaline synthetase promoter, a ribose bisphosphate carboxylase promoter, a ubiquitin promoter, a UBQ3 promoter, a oestrum virus promoter, a rice actin 1 promoter, a CaMV 35S promoter, a CaMV 19S promoter, a sucrose synthase promoter, and a figwort mosaic virus promoter. Chemical agent- inducible promoters are known in the art and include, but are not limited to, the maize Tn2-2 promoter, which is activated by benzenesulfonamide herbicide safeners; the maize GST promoter, which is activated by hydrophobic electrophilic compounds that are used as pre- emergent herbicides; and the tobacco PR-lapromoter, which is activated by salicylic acid. Other chemical-regulated promoters of interest include steroid-responsive promoters (see, for example, the glucocorticoid-inducible promoter in Schena, et al., (1991) Proc. Natl. Acad. Sci. USA 88:10421-10425 and McNellis, et al., (1998) Plant J. l4(2):247-257); copper-inducible system promoters; salicylate-inducible system promoters (e.g., the PRla system); glucocorticoid- inducible promoters (Aoyama et al. (1997) Plant J. 11:605-612); and ecdysone-inducible system promoters. Tissue-preferred and tissue-specific promoters can be used to control expression in a particular plant tissue. Such tissue-preferred and tissue-specific promoters include leaf-preferred promoter, root-preferred promoters; root-specific promoters, seed-preferred promoters; seed- specific promoters; and the like.

[0099] As noted above, the present disclosure provides a recombinant expression vector comprising a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. As noted above, the present disclosure provides a recombinant expression vector comprising a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure.

[00100] Suitable expression vectors include viral expression vectors (e.g. viral vectors based on vaccinia virus; poliovirus; adenovirus (see, e.g., Li et al., Invest Opthalmol Vis Sci 35:2543 2549, 1994; Borras et al., Gene Ther 6:515 524, 1999; Li and Davidson, PNAS 92:7700 7704, 1995; Sakamoto et al, H Gene Ther 5:1088 1097, 1999; WO 94/12649, WO 93/03769; WO 93/19191; WO 94/28938; WO 95/11984 and WO 95/00655); adeno-associated virus (AAV)

(see, e.g., Ali et al., Hum Gene Ther 9:81 86, 1998, Flannery et al., PNAS 94:6916 6921, 1997; Bennett et al., Invest Opthalmol Vis Sci 38:2857 2863, 1997; Jomary et al., Gene Ther 4:683 690, 1997, Rolling et al., Hum Gene Ther 10:641 648, 1999; Ali et al., Hum Mol Genet 5:591 594, 1996; Srivastava in WO 93/09239, Samulski et al., J. Vir. (1989) 63:3822-3828; Mendelson et al., Virol. (1988) 166:154-165; and Flotte et al., PNAS (1993) 90:10613-10617); SV40; herpes simplex virus; human immunodeficiency virus (see, e.g., Miyoshi et al., PNAS 94:10319 23, 1997; Takahashi et al., J Virol 73:7812 7816, 1999); a retroviral vector (e.g., Murine Leukemia Virus, spleen necrosis virus, and vectors derived from retroviruses such as Rous Sarcoma Virus, Harvey Sarcoma Virus, avian leukosis virus, a lentivirus, human immunodeficiency virus, myeloproliferative sarcoma virus, and mammary tumor virus); and the like. In some cases, a recombinant expression vector of the present disclosure is a recombinant adeno-associated virus (AAV) vector. In some cases, a recombinant expression vector of the present disclosure is a recombinant lentivirus vector. In some cases, a recombinant expression vector of the present disclosure is a recombinant retroviral vector.

[00101] Depending on the host/vector system utilized, any of a number of suitable transcription and translation control elements, including constitutive and inducible promoters, transcription enhancer elements, transcription terminators, etc. may be used in the expression vector. [00102] Methods of introducing a nucleic acid (e.g., DNA or RNA) (e.g., a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure; a nucleic acid encoding a Cas9 polypeptide; Cas9 guide RNA; a nucleic acid comprising a nucleotide sequence encoding a Cas9 guide RNA; a recombinant expression vector comprising one or more of the aforementioned nucleic acids; and the like) into a host cell are known in the art, and any convenient method can be used to introduce a nucleic acid (e.g., an expression construct) into a cell. Suitable methods include e.g., viral infection, transfection, lipofection, electroporation, calcium phosphate precipitation, polyethyleneimine (PEI)-mediated transfection, DEAE-dextran mediated transfection, liposome-mediated transfection, particle gun technology, calcium phosphate precipitation, direct microinjection, nanoparticle -mediated nucleic acid delivery, and the like.

[00103] Introducing a recombinant expression vector of the present disclosure into a cell or cells can occur in any culture media and under any culture conditions that promote the survival of the cells. Introducing the recombinant expression vector into a target cell can be carried out in vivo or ex vivo. Introducing the recombinant expression vector into a target cell can be carried out in vitro.

[00104] In some embodiments, an AcrIIA7 polypeptide-encoding nucleic acid can be provided as

RNA. The RNA can be provided by direct chemical synthesis or may be transcribed in vitro from a DNA (e.g., encoding the AcrIIA7 polypeptide). Once synthesized, the RNA may be introduced into a cell by any of the well-known techniques for introducing nucleic acids into cells (e.g., microinjection, electroporation, transfection, etc.).

[00105] Nucleic acids may be provided to the cells using well-developed transfection techniques; see, e.g. Angel and Yanik (2010) PLoS ONE 5(7): el 1756, and the commercially available TransMessenger® reagents from Qiagen, Stemfect™ RNA Transfection Kit from Stemgent, and TransIT®-mRNA Transfection Kit from Mirus Bio LLC. See also Beumer et al. (2008) PNAS 105(50): 19821-19826.

[00106] Vectors may be provided directly to a target host cell. In other words, the cells are

contacted with a recombinant expression vector comprising a nucleic acid (e.g., a recombinant expression vector comprising a nucleic acid encoding an AcrIIA7 polypeptide; a recombinant expression vector comprising: i) a nucleic acid encoding an AcrIIA7 polypeptide; ii) a nucleotide sequence encoding a Cas9 polypeptide; and iii) a nucleotide sequence encoding a Cas9 guide RNA; etc.) such that the vectors are taken up by the cells. Methods for contacting cells with nucleic acid vectors that are plasmids, include electroporation, calcium chloride transfection, microinjection, and lipofection are well known in the art. For viral vector delivery, cells can be contacted with viral particles comprising the subject viral expression vectors.

[00107] Retroviruses, for example, lentiviruses, are suitable for use in methods of the present disclosure. Commonly used retroviral vectors are“defective”, i.e. unable to produce viral proteins required for productive infection. Rather, replication of the vector requires growth in a packaging cell line. To generate viral particles comprising nucleic acids of interest, the retroviral nucleic acids comprising the nucleic acid are packaged into viral capsids by a packaging cell line. Different packaging cell lines provide a different envelope protein (ecotropic, amphotropic or xenotropic) to be incorporated into the capsid, this envelope protein determining the specificity of the viral particle for the cells (ecotropic for murine and rat; amphotropic for most mammalian cell types including human, dog and mouse; and xenotropic for most mammalian cell types except murine cells). The appropriate packaging cell line may be used to ensure that the cells are targeted by the packaged viral particles. Methods of introducing subject vector expression vectors into packaging cell lines and of collecting the viral particles that are generated by the packaging lines are well known in the art. Nucleic acids can also introduced by direct micro-injection (e.g., injection of RNA).

[00108] A recombinant expression vector used for providing a nucleic acid comprising a

nucleotide sequence encoding an AcrIIA7 polypeptide (and, optionally, encoding a Cas9 polypeptide and/or a Cas9 guide RNA) to a target host cell can include suitable promoters for driving the expression, that is, transcriptional activation, of the nucleic acid of interest. In other words, in some cases, the nucleic acid of interest will be operably linked to a promoter. In addition, recombinant expression vector used for providing a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide (and, optionally, encoding a Cas9 polypeptide and/or a Cas9 guide RNA) to a cell may include nucleic acid sequences that encode for selectable markers in the target cells, so as to identify cells that have taken up the recombinant expression vector.

[00109] In some cases, an expression vector of the present disclosure comprises: a) a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; and b) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above). In some cases, the nucleotide sequence encoding the AcrIIA7 polypeptide and the nucleotide sequence encoding the Cas9 polypeptide are operably linked to the same promoter. In some cases, the nucleotide sequence encoding the AcrIIA7 polypeptide is operably linked to a first promoter; and the nucleotide sequence encoding the Cas9 polypeptide is operably linked to a second promoter, where the second promoter is different from the first promoter.

[00110] In some cases, an expression vector of the present disclosure comprises: a) a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; b) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); and c) a nucleotide sequence encoding a Cas9 guide RNA. In some cases, the nucleotide sequence encoding the AcrIIA7 polypeptide, the nucleotide sequence encoding the Cas9 polypeptide, and the nucleotide sequence encoding the Cas9 guide RNA are operably linked to the same promoter. In some cases, the nucleotide sequence encoding the AcrIIA7 polypeptide is operably linked to a first promoter; and the nucleotide sequence encoding the Cas9 polypeptide and the nucleotide sequence encoding the Cas9 guide RNA are operably linked to a second promoter, where the second promoter is different from the first promoter.

MODIFIED HOST CELLS

[00111] The present disclosure provides a modified host cell comprising an AcrIIA7 polypeptide of the present disclosure and/or a nucleic acid (e.g., a recombinant expression vector) comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. In some cases, the modified host cell is one that does not normally comprise an AcrIIA7 polypeptide of the present disclosure; i.e., the AcrIIA7 polypeptide is heterologous to the host cell.

[00112] The present disclosure provides a modified cell (e.g., a genetically modified cell)

comprising nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a genetically modified cell that is genetically modified with an mRNA comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a genetically modified cell that is genetically modified with a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a genetically modified cell that is genetically modified with a recombinant expression vector comprising: a) a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; b) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is inhibited by an AcrIIA7 polypeptide of the present disclosure); and c) a nucleotide sequence encoding a Cas9guide RNA.

[00113] A cell that serves as a recipient for an AcrIIA7 polypeptide of the present disclosure and/or a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure can be any of a variety of cells, including, e.g., in vitro cells; in vivo cells; ex vivo cells; primary cells; cancer cells; animal cells; plant cells; algal cells; fungal cells; insect cells; arachnid cells; etc. A cell that serves as a recipient for an AcrIIA7 polypeptide of the present disclosure and/or a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure is referred to as a“host cell” or a“target cell.” A host cell or a target cell can be a recipient of an AcrIIA7 system of the present disclosure. A host cell or a target cell can be a recipient of a single component of an AcrIIA7 system of the present disclosure.

[00114] Non-limiting examples of cells (target cells) include: a prokaryotic cell, eukaryotic cell, a bacterial cell, an archaeal cell, a cell of a single-cell eukaryotic organism, a protozoa cell, a cell from a plant (e.g., cells from plant crops, fruits, vegetables, grains, soy bean, corn, maize, wheat, seeds, tomatos, rice, cassava, sugarcane, pumpkin, hay, potatos, cotton, cannabis, tobacco, flowering plants, conifers, gymnosperms, angiosperms, ferns, clubmosses, hornworts, liverworts, mosses, dicotyledons, monocotyledons, etc.), an algal cell, (e.g., Botryococcus braunii,

Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens, C. agardh, and the like), seaweeds (e.g. kelp) a fungal cell (e.g., a yeast cell, a cell from a mushroom), an animal cell, a cell from an invertebrate animal (e.g., fruit fly, cnidarian, echinoderm, nematode, etc.), a cell from a vertebrate animal (e.g., fish, amphibian, reptile, bird, mammal), a cell from a mammal (e.g., an ungulate (e.g., a pig, a cow, a goat, a sheep, a horse, a camel); a rodent (e.g., a rat, a mouse); a non-human primate; a human; a feline (e.g., a cat); a canine (e.g., a dog); etc.) and the like. In some cases, the cell is a cell that does not originate from a natural organism (e.g., the cell can be a synthetically made cell; also referred to as an artificial cell).

[00115] A cell can be an in vitro cell (e.g., a cell in culture, e.g., an established cultured cell line).

A cell can be an ex vivo cell (cultured cell from an individual). A cell can be an in vivo cell (e.g., a cell in an individual). A cell can be an isolated cell. A cell can be a cell inside of an organism. A cell can be an organism. A cell can be a cell in a cell culture (e.g., in vitro cell culture). A cell can be one of a collection of cells. A cell can be a prokaryotic cell or derived from a prokaryotic cell. A cell can be a bacterial cell or can be derived from a bacterial cell. A cell can be an archaeal cell or derived from an archaeal cell. A cell can be a eukaryotic cell or derived from a eukaryotic cell. A cell can be a plant cell or derived from a plant cell. A cell can be an animal cell or derived from an animal cell. A cell can be an invertebrate cell or derived from an invertebrate cell. A cell can be a vertebrate cell or derived from a vertebrate cell. A cell can be a mammalian cell or derived from a mammalian cell. A cell can be a rodent cell or derived from a rodent cell. A cell can be a human cell or derived from a human cell. A cell can be a microbe cell or derived from a microbe cell. A cell can be a fungi cell or derived from a fungi cell. A cell can be an insect cell. A cell can be an arthropod cell. A cell can be a protozoan cell. A cell can be a helminth cell.

[00116] Suitable cells include a stem cell (e.g. an embryonic stem (ES) cell, an induced

pluripotent stem (iPS) cell; a germ cell (e.g., an oocyte, a sperm, an oogonia, a spermatogonia, etc.); a somatic cell, e.g. a fibroblast, an oligodendrocyte, a glial cell, a hematopoietic cell, a neuron, a muscle cell, a bone cell, a hepatocyte, a pancreatic cell, etc.

[00117] Suitable cells include human embryonic stem cells, fetal cardiomyocytes,

myofibroblasts, mesenchymal stem cells, cardiomyocytes, adipocytes, totipotent cells, pluripotent cells, blood stem cells, myoblasts, adult stem cells, bone marrow cells, mesenchymal cells, embryonic stem cells, parenchymal cells, epithelial cells, endothelial cells, mesothelial cells, fibroblasts, osteoblasts, chondrocytes, exogenous cells, endogenous cells, stem cells, hematopoietic stem cells, bone-marrow derived progenitor cells, myocardial cells, skeletal cells, fetal cells, undifferentiated cells, multi-potent progenitor cells, unipotent progenitor cells, monocytes, cardiac myoblasts, skeletal myoblasts, macrophages, capillary endothelial cells, xenogenic cells, allogenic cells, and post-natal stem cells.

[00118] In some cases, the cell is an immune cell, a neuron, an epithelial cell, and endothelial cell, or a stem cell. In some cases, the immune cell is a T cell, a B cell, a monocyte, a natural killer cell, a dendritic cell, or a macrophage. In some cases, the immune cell is a cytotoxic T cell. In some cases, the immune cell is a helper T cell. In some cases, the immune cell is a regulatory T cell (Treg).

[00119] In some cases, the cell is a stem cell. Stem cells include adult stem cells. Adult stem cells are also referred to as somatic stem cells.

[00120] Adult stem cells are resident in differentiated tissue, but retain the properties of self renewal and ability to give rise to multiple cell types, usually cell types typical of the tissue in which the stem cells are found. Numerous examples of somatic stem cells are known to those of skill in the art, including muscle stem cells; hematopoietic stem cells; epithelial stem cells; neural stem cells; mesenchymal stem cells; mammary stem cells; intestinal stem cells;

mesodermal stem cells; endothelial stem cells; olfactory stem cells; neural crest stem cells; and the like.

[00121] Stem cells of interest include mammalian stem cells, where the term“mammalian” refers to any animal classified as a mammal, including humans; non-human primates; domestic and farm animals; and zoo, laboratory, sports, or pet animals, such as dogs, horses, cats, cows, mice, rats, rabbits, etc. In some cases, the stem cell is a human stem cell. In some cases, the stem cell is a rodent (e.g., a mouse; a rat) stem cell. In some cases, the stem cell is a non-human primate stem cell.

[00122] Stem cells can express one or more stem cell markers, e.g., SOX9, KRT19, KRT7,

LGR5, CA9, FXYD2, CDH6, CLDN18, TSPAN8, BPIFB1, OLFM4, CDH17, and PPARGC1A.

[00123] In some cases, the stem cell is a hematopoietic stem cell (HSC). HSCs are mesoderm- derived cells that can be isolated from bone marrow, blood, cord blood, fetal liver and yolk sac. HSCs are characterized as CD34+ and CD3-. HSCs can repopulate the erythroid, neutrophil- macrophage, megakaryocyte and lymphoid hematopoietic cell lineages in vivo. HSCs can be induced in vitro to undergo at least some self-renewing cell divisions and can be induced to differentiate to the same lineages as is seen in vivo. As such, HSCs can be induced to differentiate into one or more of erythroid cells, megakaryocytes, neutrophils, macrophages, and lymphoid cells.

[00124] In other instances, the stem cell is a neural stem cell (NSC). Neural stem cells (NSCs) are capable of differentiating into neurons, and glia (including oligodendrocytes, and astrocytes). A neural stem cell is a multipotent stem cell which is capable of multiple divisions, and under specific conditions can produce daughter cells which are neural stem cells, or neural progenitor cells that can be neuroblasts or glioblasts, e.g., cells committed to become one or more types of neurons and glial cells respectively. Methods of obtaining NSCs are known in the art.

[00125] In other cases, the stem cell is a mesenchymal stem cell (MSC). MSCs originally

derived from the embryonal mesoderm and isolated from adult bone marrow, can differentiate to form muscle, bone, cartilage, fat, marrow stroma, and tendon. Methods of isolating MSC are known in the art; and any known method can be used to obtain MSC. See, e.g., U.S. Pat. No. 5,736,396, which describes isolation of human MSC.

[00126] A cell is in some cases a plant cell. A plant cell can be a cell of a monocotyledon. A cell can be a cell of a dicotyledon.

[00127] In some cases, the cell is a plant cell. For example, the cell can be a cell of a major

agricultural plant, e.g., Barley, Beans (Dry Edible), Canola, Corn, Cotton (Pima), Cotton (Upland), Flaxseed, Hay (Alfalfa), Hay (Non- Alfalfa), Oats, Peanuts, Rice, Sorghum, Soybeans, Sugarbeets, Sugarcane, Sunflowers (Oil), Sunflowers (Non-Oil), Sweet Potatoes , Tobacco (Burley), Tobacco (Flue-cured), Tomatoes, Wheat (Durum), Wheat (Spring), Wheat (Winter), and the like. As another example, the cell is a cell of a vegetable crops which include but are not limited to, e.g., alfalfa sprouts, aloe leaves, arrow root, arrowhead, artichokes, asparagus, bamboo shoots, banana flowers, bean sprouts, beans, beet tops, beets, bittermelon, bok choy, broccoli, broccoli rabe (rappini), brussels sprouts, cabbage, cabbage sprouts, cactus leaf (nopales), calabaza, cardoon, carrots, cauliflower, celery, chayote, Chinese artichoke (crosnes), Chinese cabbage, Chinese celery, Chinese chives, choy sum, chrysanthemum leaves (tung ho), collard greens, corn stalks, corn-sweet, cucumbers, daikon, dandelion greens, dasheen, dau mue (pea tips), donqua (winter melon), eggplant, endive, escarole, fiddle head ferns, field cress, frisee, gai choy (Chinese mustard), gallon, galanga (siam, thai ginger), garlic, ginger root, gobo, greens, hanover salad greens, huauzontle, jerusalem artichokes, jicama, kale greens, kohlrabi, lamb's quarters (quilete), lettuce (bibb), lettuce (boston), lettuce (boston red), lettuce (green leaf), lettuce (iceberg), lettuce (lolla rossa), lettuce (oak leaf - green), lettuce (oak leaf - red), lettuce (processed), lettuce (red leaf), lettuce (romaine), lettuce (ruby romaine), lettuce (russian red mustard), linkok, lo bok, long beans, lotus root, mache, maguey (agave) leaves, malanga, mesculin mix, mizuna, moap (smooth luffa), moo, moqua (fuzzy squash), mushrooms, mustard, nagaimo, okra, ong choy, onions green, opo (long squash), ornamental corn, ornamental gourds, parsley, parsnips, peas, peppers (bell type), peppers, pumpkins, radicchio, radish sprouts, radishes, rape greens, rape greens, rhubarb, romaine (baby red), rutabagas, salicornia (sea bean), sinqua (angled/ridged luffa), spinach, squash, straw bales, sugarcane, sweet potatoes, swiss chard, tamarindo, taro, taro leaf, taro shoots, tatsoi, tepeguaje (guaje), tindora, tomatillos, tomatoes, tomatoes (cherry), tomatoes (grape type), tomatoes (plum type), tumeric, turnip tops greens, turnips, water chestnuts, yampi, yams (names), yu choy, yuca (cassava), and the like.

[00128] A cell is in some cases an arthropod cell. For example, the cell can be a cell of a sub order, a family, a sub-family, a group, a sub-group, or a species of, e.g., Chelicerata,

Myriapodia, Hexipodia, Arachnida, Insecta, Archaeognatha, Thysanura, Palaeoptera,

Ephemeroptera, Odonata, Anisoptera, Zygoptera, Neoptera, Exopterygota, Plecoptera , Embioptera , Orthoptera, Zoraptera , Dermaptera, Dictyoptera, Notoptera, Grylloblattidae, Mantophasmatidae, Phasmatodea , Blattaria, Isoptera, Mantodea, Parapneuroptera, Psocoptera, Thysanoptera, Phthiraptera, Hemiptera, Endopterygota or Holometabola , Hymenoptera , Coleoptera, Strepsiptera, Raphidioptera, Megaloptera, Neuroptera , Mecoptera , Siphonaptera, Diptera, Trichoptera, or Lepidoptera.

[00129] A cell is in some cases an insect cell. For example, in some cases, the cell is a cell of a mosquito, a grasshopper, a true bug, a fly, a flea, a bee, a wasp, an ant, a louse, a moth, or a beetle.

COMPOSITIONS

[00130] The present disclosure provides a composition comprising an AcrIIA7 polypeptide of the present disclosure. The present disclosure comprises a composition comprising a nucleic acid or a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a composition comprising an AcrIIA7 fusion polypeptide of the present disclosure.

[00131] For example, one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, can be delivered (non- contemporaneously or simultaneously) using particles or lipids (e.g., liposomes). For example, any one of, or any combination of, (a)-(g) as set out above can be delivered associated with, or encapsulated in, a nanoparticle. For example, any one of, or any combination of, (a)-(g) as set out above can be delivered associated with, or encapsulated in, a lipid composition, e.g., a lipid composition (such as a liposome) comprising a lipid or lipidoid and a hydrophilic polymer, e.g., a cationic lipid and a hydrophilic polymer, for instance wherein the cationic lipid comprises 1 ,2- dioleoyl-3-trimethylammonium-propane (DOTAP) or l,2-ditetradecanoyl-sn-glycero-3- phosphocholine (DMPC) and/or wherein the hydrophilic polymer comprises ethylene glycol or polyethylene glycol (PEG); and/or wherein the lipid composition further comprises cholesterol (e.g., particle from formulation l=DOTAP 100, DMPC 0, PEG 0, Cholesterol 0; formulation number 2=DOTAP 90, DMPC 0, PEG 10, Cholesterol 0; formulation number 3=DOTAP 90, DMPC 0, PEG 5, Cholesterol 5). For example, a lipid composition can be formed using a multistep process in which an AcrIIA7 polypeptide, a Cas9 polypeptide, and a Cas9 guideRNA are mixed together, e.g., at a 1:1:1 molar ratio, e.g., at room temperature, e.g., for 30 minutes, e.g., in sterile, nuclease free 1 x phosphate-buffered saline (PBS); and separately, DOTAP, DMPC, PEG, and cholesterol as applicable for the formulation are dissolved in alcohol, e.g., 100% ethanol; and, the two solutions are mixed together to form particles containing the complexes).

[00132] In some cases, one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, are delivered using particles or lipid envelopes. For example, a biodegradable core-shell structured nanoparticle with a poly (b-amino ester) (PBAE) core enveloped by a phospholipid bilayer shell can be used. In some cases, particles/nanoparticles based on self assembling bioadhesive polymers are used; such particles/nanoparticles may be applied to oral delivery of peptides, intravenous delivery of peptides and nasal delivery of peptides, e.g., to the brain. Other embodiments, such as oral absorption and ocular delivery of hydrophobic drugs are also contemplated. A molecular envelope technology, which involves an engineered polymer envelope which is protected and delivered to the site of the disease, can be used. Doses of about 5 mg/kg can be used, with single or multiple doses, depending on various factors, e.g., the target tissue.

[00133] Lipidoid compounds (e.g., as described in US patent application 20110293703) are also useful in the administration of polynucleotides, and can be used to deliver one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure. In one aspect, the aminoalcohol lipidoid compounds are combined with an agent (one or more of (a)-(f), above), to be delivered to a cell or a subject to form

microparticles, nanoparticles, liposomes, or micelles. The aminoalcohol lipidoid compounds may be combined with other aminoalcohol lipidoid compounds, polymers (synthetic or natural), surfactants, cholesterol, carbohydrates, proteins, lipids, etc. to form the particles. These particles may then optionally be combined with a pharmaceutical excipient to form a pharmaceutical composition.

[00134] A poly(beta-amino alcohol) (PBAA) can be used to deliver one or more of: a)

recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, to a target cell. US Patent Publication No. 20130302401 relates to a class of poly(beta-amino alcohols) (PBAAs) that has been prepared using combinatorial polymerization.

[00135] Sugar-based particles may be used, for example GalNAc, as described with reference to

WO2014118272 (incorporated herein by reference) and Nair, J K et al., 2014, Journal of the American Chemical Society 136 (49), 16958-16961) can be used to deliver one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, to a target cell.

[00136] In some cases, lipid nanoparticles (LNPs) are used to deliver one or more of: a)

recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, to a target cell. Negatively charged polymers such as RNA may be loaded into LNPs at low pH values (e.g., pH 4) where the ionizable lipids display a positive charge. However, at physiological pH values, the LNPs exhibit a low surface charge compatible with longer circulation times. Four species of ionizable cationic lipids have been focused upon, namely l,2-dilineoyl-3-dimethylammonium-propane (DLinDAP), l,2-dilinoleyloxy-3-N,N- dimethylaminopropane (DLinDMA), 1 ,2-dilinoleyloxy-keto-N,N-dimethyl-3-aminopropane (DLinKDMA), and l,2-dilinoleyl-4-(2-dimethylaminoethyl)-[l,3]-dioxolane (DLinKC2-DMA). Preparation of LNPs and is described in, e.g., Rosin et al. (2011) Molecular Therapy 19:1286- 2200). The cationic lipids l,2-dilineoyl-3-dimethylammonium-propane (DLinDAP), 1,2- dilinoleyloxy-3-N,N-dimethylaminopropane (DLinDMA), 1 ,2-dilinoleyloxyketo-N,N-dimethyl- 3-aminopropane (DLinK-DMA), l,2-dilinoleyl-4-(2-dimethylaminoethyl)-[l,3]-dioxolane (DLinKC2-DMA), (3-o-[2"-(methoxypolyethyleneglycol 2000) succinoyl]-l,2-dimyristoyl-sn- glycol (PEG-S-DMG), and R-3-[(omega-methoxy-poly(ethylene glycol)2000) carbamoyl] -1,2- dimyristyloxlpropyl-3-amine (PEG-C-DOMG) may be used. A nucleic acid (e.g., a Cas9 guide RNA; a nucleic acid of the present disclosure; etc.) may be encapsulated in LNPs containing DLinDAP, DLinDMA, DLinK-DMA, and DLinKC2-DMA (cationic lipid:DSPC:CHOL: PEGS- DMG or PEG-C-DOMG at 40:10:40:10 molar ratios). In some cases, 0.2% SP-DiOCl8 is incorporated. [00137] Spherical Nucleic Acid (SNA™) constructs and other nanoparticles (particularly gold nanoparticles) can be used to deliver one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure, to a target cell.. See, e.g., Cutler et al., J. Am. Chem. Soc. 2011 133:9254-9257, Hao et al., Small. 2011 7:3158-3162, Zhang et al., ACS Nano. 2011 5:6962-6970, Cutler et al., J. Am. Chem. Soc. 2012 134:1376-1391, Young et al., Nano Lett. 2012 12:3867-71, Zheng et al., Proc. Natl. Acad. Sci. USA. 2012 109:11975-80, Mirkin, Nanomedicine 2012 7:635-638 Zhang et al., J. Am. Chem. Soc. 2012 134:16488-1691, Weintraub, Nature 2013 495:Sl4-Sl6, Choi et al., Proc. Natl. Acad. Sci. USA. 2013 110(19): 7625-7630, Jensen et al., Sci. Transl. Med. 5, 209ral52 (2013) and Mirkin, et al., Small, 10:186-192.

[00138] Self-assembling nanoparticles with RNA may be constructed with polyethyleneimine

(PEI) that is PEGylated with an Arg-Gly-Asp (RGD) peptide ligand attached at the distal end of the polyethylene glycol (PEG).

[00139] In general, a "nanoparticle" refers to any particle having a diameter of less than 1000 nm. In some cases, nanoparticles suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell have a diameter of 500 nm or less, e.g., from 25 nm to 35 nm, from 35 nm to 50 nm, from 50 nm to 75 nm, from 75 nm to 100 nm, from 100 nm to 150 nm, from 150 nm to 200 nm, from 200 nm to 300 nm, from 300 nm to 400 nm, or from 400 nm to 500 nm.

[00140] In some cases, nanoparticles suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell have a diameter of from 25 nm to 200 nm.

[00141] In some cases, nanoparticles suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell have a diameter of 100 nm or less. In some cases, nanoparticles suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell have a diameter of from 35 nm to 60 nm.

[00142] Nanoparticles suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell may be provided in different forms, e.g., as solid nanoparticles (e.g., metal such as silver, gold, iron, titanium), non-metal, lipid-based solids, polymers), suspensions of nanoparticles, or combinations thereof. Metal, dielectric, and semiconductor nanoparticles may be prepared, as well as hybrid structures (e.g., core-shell nanoparticles). Nanoparticles made of semiconducting material may also be labeled quantum dots if they are small enough (typically below 10 nm) that quantization of electronic energy levels occurs. Such nanoscale particles are used in biomedical applications as drug carriers or imaging agents and may be adapted for similar purposes in the present disclosure.

[00143] Semi-solid and soft nanoparticles are also suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. A prototype nanoparticle of semi-solid nature is the liposome.

[00144] In some cases, an exosome is used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. Exosomes are endogenous nano-vesicles that transport RNAs and proteins, and which can deliver RNA to the brain and other target organs.

[00145] In some cases, a liposome is used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. Liposomes are spherical vesicle structures composed of a uni- or multilamellar lipid bilayer surrounding internal aqueous compartments and a relatively impermeable outer lipophilic phospholipid bilayer. Liposomes can be made from several different types of lipids; however, phospholipids are most commonly used to generate liposomes. Although liposome formation is spontaneous when a lipid film is mixed with an aqueous solution, it can also be expedited by applying force in the form of shaking by using a homogenizer, sonicator, or an extrusion apparatus. Several other additives may be added to liposomes in order to modify their structure and properties. For instance, either cholesterol or sphingomyelin may be added to the liposomal mixture in order to help stabilize the liposomal structure and to prevent the leakage of the liposomal inner cargo. A liposome formulation may be mainly comprised of natural phospholipids and lipids such as l,2-distearoryl-sn-glycero-3- phosphatidyl choline (DSPC), sphingomyelin, egg phosphatidylcholines and

monosialoganglioside .

[00146] A stable nucleic-acid-lipid particle (SNALP) can be used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. The SNALP formulation may contain the lipids 3 -N-[(methoxypoly (ethylene glycol) 2000) carbamoyl] - 1 ,2-dimyristyloxy-propylamine (PEG-C-DMA), 1 ,2-dilinoleyloxy-N,N-dimethyl-3- aminopropane (DLinDMA), l,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and cholesterol, in a 2:40:10:48 molar percent ratio. The SNALP liposomes may be prepared by formulating D-Lin-DMA and PEG-C-DMA with distearoylphosphatidylcholine (DSPC), Cholesterol and siRNA using a 25:1 lipid/siRNA ratio and a 48/40/10/2 molar ratio of

Cholesterol/D-Lin-DMA/DSPC/PEG-C-DMA. The resulting SNALP liposomes can be about 80-100 nm in size. A SNALP may comprise synthetic cholesterol (Sigma-Aldrich, St Louis,

Mo., USA), dipalmitoylphosphatidylcholine (Avanti Polar Lipids, Alabaster, Ala., USA), 3-N- [(w-methoxy poly(ethylene glycol)2000)carbamoyl]-l,2-dimyrestyloxypropylamine, and cationic 1 ,2-dilinoleyloxy-3-N,Ndimethylaminopropane. A SNALP may comprise synthetic cholesterol (Sigma-Aldrich), l,2-distearoyl-sn-glycero-3-phosphocholine (DSPC; Avanti Polar Lipids Inc.), PEG-cDMA, and l,2-dilinoleyloxy-3-(N;N-dimethyl)aminopropane (DLinDMA).

[00147] Other cationic lipids, such as amino lipid 2,2-dilinoleyl-4-dimethylaminoethyl-[l,3]- dioxolane (DLin-KC2-DMA) can be used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. A preformed vesicle with the following lipid composition may be contemplated: amino lipid, distearoylphosphatidylcholine (DSPC), cholesterol and (R)-2,3-bis(octadecyloxy) propyl- l-(methoxy poly(ethylene

glycol)2000)propylcarbamate (PEG-lipid) in the molar ratio 40/10/40/10, respectively, and a LVII siRNA/total lipid ratio of approximately 0.05 (w/w). To ensure a narrow particle size distribution in the range of 70-90 nm and a low polydispersity index of 0.11.+-.0.04 (n=56), the particles may be extruded up to three times through 80 nm membranes prior to adding the guide RNA. Particles containing the highly potent amino lipid 16 may be used, in which the molar ratio of the four lipid components 16, DSPC, cholesterol and PEG-lipid (50/10/38.5/1.5) which may be further optimized to enhance in vivo activity.

[00148] Lipids may be formulated with a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to form lipid nanoparticles (LNPs). Suitable lipids include, but are not limited to, DLin-KC2-DMA4, Cl 2-200 and colipids disteroylphosphatidyl choline, cholesterol, and PEG-DMG may be formulated with a system, or component thereof, of the present disclosure, using a spontaneous vesicle formation procedure. The component molar ratio may be about 50/10/38.5/1.5 (DLin-KC2-DMA or Cl2-200/disteroylphosphatidyl

choline/cholesterol/PEG-DMG) .

[00149] A polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) may be delivered encapsulated in PLGA microspheres such as that further described in US published applications 20130252281 and 20130245107 and 20130244279.

[00150] Supercharged proteins can be used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. Supercharged proteins are a class of engineered or naturally occurring proteins with unusually high positive or negative net theoretical charge. Both supernegatively and superpositively charged proteins exhibit the ability to withstand thermally or chemically induced aggregation. Superpositively charged proteins are also able to penetrate mammalian cells. Associating cargo with these proteins, such as plasmid DNA, RNA, or other proteins, can enable the functional delivery of these macromolecules into mammalian cells both in vitro and in vivo.

[00151] Cell Penetrating Peptides (CPPs) can be used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell. CPPs typically have an amino acid composition that either contains a high relative abundance of positively charged amino acids such as lysine or arginine or has sequences that contain an alternating pattern of polar/charged amino acids and non-polar, hydrophobic amino acids.

[00152] An implantable device can be used to deliver a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell (e.g., a target cell in vivo, where the target cell is a target cell in circulation, a target cell in a tissue, a target cell in an organ, etc.). An implantable device suitable for use in delivering a polypeptide and/or a nucleic acid (e.g., one or more of: a) recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); e) a Cas9 guide RNA; f) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and g) an AcrIIA7 polypeptide or an AcrIIA7 fusion polypeptide of the present disclosure) to a target cell (e.g., a target cell in vivo, where the target cell is a target cell in circulation, a target cell in a tissue, a target cell in an organ, etc.) can include a container (e.g., a reservoir, a matrix, etc.) that comprises the polypeptide or nucleic acid (or combinations).

[00153] A suitable implantable device can comprise a polymeric substrate, such as a matrix for example, that is used as the device body, and in some cases additional scaffolding materials, such as metals or additional polymers, and materials to enhance visibility and imaging. An implantable delivery device can be advantageous in providing release locally and over a prolonged period, where the polypeptide and/or nucleic acid to be delivered is released directly to a target site, e.g., the extracellular matrix (ECM), the vasculature surrounding a tumor, a diseased tissue, etc. Suitable implantable delivery devices include devices suitable for use in delivering to a cavity such as the abdominal cavity and/or any other type of administration in which the drug delivery system is not anchored or attached, comprising a biostable and/or degradable and/or bioabsorbable polymeric substrate, which may for example optionally be a matrix. In some cases, a suitable implantable drug delivery device comprises degradable polymers, wherein the main release mechanism is bulk erosion. In some cases, a suitable implantable drug delivery device comprises non degradable, or slowly degraded polymers, wherein the main release mechanism is diffusion rather than bulk erosion, so that the outer part functions as membrane, and its internal part functions as a drug reservoir, which practically is not affected by the surroundings for an extended period (for example from about a week to about a few months). Combinations of different polymers with different release mechanisms may also optionally be used. The concentration gradient at the can be maintained effectively constant during a significant period of the total releasing period, and therefore the diffusion rate is effectively constant (termed "zero mode" diffusion). By the term "constant" it is meant a diffusion rate that is maintained above the lower threshold of therapeutic effectiveness, but which may still optionally feature an initial burst and/or may fluctuate, for example increasing and decreasing to a certain degree. The diffusion rate can be so maintained for a prolonged period, and it can be considered constant to a certain level to optimize the therapeutically effective period, for example the effective silencing period.

[00154] In some cases, the implantable delivery system is designed to shield a nucleic acid

component from degradation, whether chemical in nature or due to attack from enzymes and other factors in the body of the subject.

[00155] The site for implantation of the device, or target site, can be selected for maximum

therapeutic efficacy. For example, a delivery device can be implanted within or in the proximity of a tumor environment, or the blood supply associated with a tumor. The target location can be, e.g.: 1) the brain at degenerative sites like in Parkinson or Alzheimer disease at the basal ganglia, white and gray matter; 2) the spine, as in the case of amyotrophic lateral sclerosis (ALS); 3) uterine cervix; 4) active and chronic inflammatory joints; 5) dermis as in the case of psoriasis; 7) sympathetic and sensoric nervous sites for analgesic effect; 7) a bone; 8) a site of acute or chronic infection; 9) Intra vaginal; 10) Inner ear— auditory system, labyrinth of the inner ear, vestibular system; 11) Intra tracheal; 12) Intra-cardiac; coronary, epicardiac; 13) urinary tract or bladder; 14) biliary system; 15) parenchymal tissue including and not limited to the kidney, liver, spleen; 16) lymph nodes; 17) salivary glands; 18) dental gums; 19) Intra-articular (into joints); 20) Intra-ocular; 21) Brain tissue; 22) Brain ventricles; 23) Cavities, including abdominal cavity (for example but without limitation, for ovary cancer); 24) Intra esophageal; and 25) Intra rectal; and 26) into the vasculature.

SYSTEMS

[00156] The present disclosure provides a system for controlling activity of a Cas9 polypeptide.

A system of the present disclosure can comprise two or more of: a) an AcrIIA7 polypeptide of the present disclosure, an AcrIIA7 fusion polypeptide of the present disclosure, or a modified AcrIIA7 polypeptide of the present disclosure; b) an RNA comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure; c) a DNA comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure; d) a recombinant expression vector comprising a nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure or an AcrIIA7 fusion polypeptide of the present disclosure; e) a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); f) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); g) a DNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); h) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); i) a Cas9 guide RNA; j) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; k) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 guide RNA; 1) a recombinant expression vector comprising a nucleotide sequence encoding a constant region (tracRNA region) of a Cas9 guide RNA and an insertion site for inserting a nucleotide sequence encoding a crRNA portion of the Cas9 guide RNA; m) a recombinant expression vector comprising: i) a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; and ii) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); n) a recombinant expression vector comprising: i) a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; and ii) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above); and iii) a nucleotide sequence encoding a Cas9 guide RNA.

[00157] In some cases, a system of the present disclosure comprises two or more of: a)

recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure (where the recombinant expression vector may optionally include one or both of: i) a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); and ii) a nucleotide sequence encoding a Cas9 guide RNA); b) a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); c) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) an RNA comprising a nucleotide sequence encoding a Cas9 polypeptide (where the Cas9 polypeptide is one whose activity can be inhibited by the AcrIIA7 polypeptide); d) a Cas9 guide RNA; e) a DNA comprising a nucleotide sequence encoding a Cas9 guide RNA; and f) an AcrIIA7 polypeptide.

[00158] In some cases, a system of the present disclosure comprises: a) an AcrIIA7 polypeptide of the present disclosure; and b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide. In some cases, a system of the present disclosure comprises: a) an AcrIIA7 polypeptide of the present disclosure; b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and c) a Cas9 guide RNA. In some cases, a system of the present disclosure comprises: a) a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; and b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide. In some cases, a system of the present disclosure comprises: a) a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and c) a Cas9 guide RNA. In some cases, a system of the present disclosure comprises: a) a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure; b) a recombinant expression vector comprising a nucleotide sequence encoding a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and c) a Cas9 guide RNA. In some cases, a system of the present disclosure comprises: a) a

ribonucleoprotein comprising: i) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and ii) a Cas9 guide RNA; and b) an AcrIIA7 polypeptide of the present disclosure. In some cases, a system of the present disclosure comprises: a) a ribonucleoprotein comprising: i) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and ii) a Cas9 guide RNA; and b) a recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure.

AcrIIA7 polypeptides

[00159] AcrIIA7 polypeptides that are suitable for inclusion in a system of the present disclosure include: a) AcrIIA7 polypeptides as described above; b) AcrIIA7 fusion polypeptides as described above; and c) modified AcrIIA7 polypeptides as described above. A system of the present disclosure can comprise an AcrIIA7 polypeptide of the present disclosure, or a nucleic acid or recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. A system of the present disclosure can comprise an AcrIIA7 fusion polypeptide of the present disclosure, or a nucleic acid or recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 fusion polypeptide of the present disclosure. A system of the present disclosure can comprise a modified AcrIIA7 polypeptide of the present disclosure.

Cas9 polypeptides

[00160] As noted above, in some cases, a system of the present disclosure includes a Cas9

polypeptide, where the Cas9 polypeptide is one that can be inhibited by an AcrIIA7 polypeptide of the present disclosure, where such Cas9 polypeptides are described above. In some cases, a system of the present disclosure comprises: a) an AcrIIA7 polypeptide of the present disclosure; and b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide. In some cases, a system of the present disclosure comprises: a) an AcrIIA7 polypeptide of the present disclosure; b) a Cas9 polypeptide, where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide; and c) a Cas9 guide RNA.

[00161] In some cases, a Cas9 polypeptide included in a system of the present disclosure

comprises an amino acid sequence having at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Staphylococcus aureus Cas9 amino acid sequence provided in FIG. 2. [00162] A Staphylococcus aureus Cas9 (SaCas9) suitable for inclusion in a system of the present disclosure can comprise one of the following sets of amino acid substitutions: N419A/R654A, Y211A/R654A, Y211A/Y212A, Y211A/N230A, Y211A/R245A, Y212A/Y230A,

Y212A/R245A, Y230A/R245A, W229A/R654A, Y211A/Y212A/Y230A,

Y211 A/Y 212A/R245 A, Y211A/Y212A/Y651A, Y211A/Y230A/R245A,

Y211A/Y230A/Y651A, Y211A/R245A/Y651A, Y211A/R245A/R654A,

Y211 A/R245A/N419A, Y211A/N419A/R654A, Y212A/Y230A/R245A,

Y212A/Y230A/Y651A, Y212A/R245A/Y651A, Y230A/R245A/Y651A,

R245A/N419A/R654A, T392A/N419A/R654A, R245A/T392AN419A/R654A,

Y211 A/R245A/N419A/R654A, W229A/R245A/N419A/R654A,

Y211 A/R245A/T392A/N419A/R654A, and Y211 A1W229A/R245A/N419A/R654A.

[00163] A Staphylococcus aureus Cas9 (SaCas9) suitable for inclusion in a system of the present disclosure comprises one of the following amino acid substitutions or sets of amino acid substitutions: E782K; K929R; N968K; R1015H; E782K/N968K/R1015H (KKH variant);

E782K/K929R/R1015H (KRH variant); or E782K/K929R/N968K/R1015H (KRKH variant).

[00164] In some cases, a Cas9 polypeptide comprising an amino acid sequence having at least

50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, at least 99%, or 100%, amino acid sequence identity to the Lactobacillus gasseri amino acid sequence provided in FIG. 6 is specifically excluded from a system of the present disclosure.

Cas9 guide RNA

[00165] A nucleic acid molecule that binds to a Cas9 protein and targets the complex to a

specific location within a target nucleic acid is referred to herein as a“Cas9 guide RNA.”

[00166] A Cas9 guide RNA (can be said to include two segments, a first segment (referred to herein as a“targeting segment”); and a second segment (referred to herein as a“protein-binding segment”). By“segment” it is meant a segment/section/region of a molecule, e.g., a contiguous stretch of nucleotides in a nucleic acid molecule. A segment can also refer to a region/section of a complex such that a segment may comprise regions of more than one molecule.

[00167] The first segment (targeting segment) of a Cas9 guide RNA includes a nucleotide

sequence (a guide sequence) that is complementary to (and therefore hybridizes with) a specific sequence (a target site) within a target nucleic acid (e.g., a target ssRNA, a target ssDNA, the complementary strand of a double stranded target DNA, etc.). The protein-binding segment (or “protein-binding sequence”) interacts with (binds to) a Cas9 polypeptide. The protein-binding segment of a subject Cas9 guide RNA includes two complementary stretches of nucleotides that hybridize to one another to form a double stranded RNA duplex (dsRNA duplex). Site-specific binding and/or cleavage of a target nucleic acid (e.g., genomic DNA) can occur at locations (e.g., target sequence of a target locus) determined by base-pairing complementarity between the Cas9 guide RNA (the guide sequence of the Cas9 guide RNA) and the target nucleic acid.

[00168] A Cas9 guide RNA and a Cas9 protein form a complex (e.g., bind via non-covalent interactions). The Cas9 guide RNA provides target specificity to the complex by including a targeting segment, which includes a guide sequence (a nucleotide sequence that is

complementary to a sequence of a target nucleic acid). The Cas9 protein of the complex provides the site-specific activity (e.g., cleavage activity or an activity provided by the Cas9 protein when the Cas9 protein is a Cas9 fusion polypeptide, i.e., has a fusion partner). In other words, the Cas9 protein is guided to a target nucleic acid sequence (e.g. a target sequence in a chromosomal nucleic acid, e.g., a chromosome; a target sequence in an extrachromosomal nucleic acid, e.g. an episomal nucleic acid, a minicircle, an ssRNA, an ssDNA, etc. ; a target sequence in a mitochondrial nucleic acid; a target sequence in a chloroplast nucleic acid; a target sequence in a plasmid; a target sequence in a viral nucleic acid; etc.) by virtue of its association with the Cas9 guide RNA.

[00169] The“guide sequence” also referred to as the“targeting sequence” of a Cas9 guide RNA can be modified so that the Cas9 guide RNA can target a Cas9 protein to any desired sequence of any desired target nucleic acid, with the exception that the protospacer adjacent motif (PAM) sequence is taken into account. Thus, for example, a Cas9 guide RNA can have a targeting segment with a sequence (a guide sequence) that has complementarity with (e.g., can hybridize to) a sequence in a nucleic acid in a eukaryotic cell, e.g., a viral nucleic acid, a eukaryotic nucleic acid (e.g., a eukaryotic chromosome, chromosomal sequence, a eukaryotic RNA, etc.), and the like.

[00170] In some embodiments, a Cas9 guide RNA includes two separate nucleic acid molecules: an“activator” and a“targeter” and is referred to herein as a“dual Cas9 guide RNA”, a“double molecule Cas9 guide RNA”, or a“two-molecule Cas9 guide RNA” a“dual guide RNA”, or a “dgRNA.” In some embodiments, the activator and targeter are covalently linked to one another (e.g., via intervening nucleotides) and the guide RNA is referred to as a“single guide RNA”, a “Cas9 single guide RNA”, a“single-molecule Cas9 guide RNA,” or a“one-molecule Cas9 guide RNA”, or simply“sgRNA.”

[00171] A Cas9 guide RNA comprises a crRNA-like (“CRISPR RNA” /“targeter” /“crRNA” /

“crRNA repeat”) molecule and a corresponding tracrRNA-like (“trans-acting CRISPR RNA” / “activator” /“tracrRNA”) molecule. A crRNA-like molecule (targeter) comprises both the targeting segment (single stranded) of the Cas9 guide RNA and a stretch (“duplex-forming segment”) of nucleotides that for s one half of the dsRNA duplex of the protein-binding segment of the Cas9 guide RNA. A corresponding tracrRNA-like molecule (activator / tracrRNA) comprises a stretch of nucleotides (duplex-forming segment) that forms the other half of the dsRNA duplex of the protein-binding segment of the guide nucleic acid. In other words, a stretch of nucleotides of a crRNA-like molecule are complementary to and hybridize with a stretch of nucleotides of a tracrRNA-like molecule to form the dsRNA duplex of the protein binding domain of the Cas9 guide RNA. As such, each targeter molecule can be said to have a corresponding activator molecule (which has a region that hybridizes with the targeter). The targeter molecule additionally provides the targeting segment. Thus, a targeter and an activator molecule (as a corresponding pair) hybridize to form a Cas9 guide RNA. The exact sequence of a given crRNA or tracrRNA molecule is characteristic of the species in which the RNA molecules are found. A subject dual Cas9 guide RNA can include any corresponding activator and targeter pair.

[00172] The term“activator” or“activator RNA” is used herein to mean a tracrRNA-like

molecule (tracrRNA:“trans-acting CRISPR RNA”) of a Cas9 dual guide RNA (and therefore of a Cas9 single guide RNA when the“activator” and the“targeter” are linked together by, e.g., intervening nucleotides). Thus, for example, a Cas9 guide RNA (dgRNA or sgRNA) comprises an activator sequence (e.g., a tracrRNA sequence). A tracr molecule (a tracrRNA) is a naturally existing molecule that hybridizes with a CRISPR RNA molecule (a crRNA) to form a Cas9 dual guide RNA. The term“activator” is used herein to encompass naturally existing tracrRNAs, but also to encompass tracrRNAs with modifications (e.g., truncations, sequence variations, base modifications, backbone modifications, linkage modifications, etc.) where the activator retains at least one function of a tracrRNA (e.g., contributes to the dsRNA duplex to which Cas9 protein binds). In some cases, the activator provides one or more stem loops that can interact with Cas9 protein. An activator can be referred to as having a tracr sequence (tracrRNA sequence) and in some cases is a tracrRNA, but the term“activator” is not limited to naturally existing tracrRNAs.

[00173] The term“targeter” or“targeter RNA” is used herein to refer to a crRNA-like molecule

(crRNA:“CRISPR RNA”) of a Cas9 dual guide RNA (and therefore of a Cas9 single guide RNA when the“activator” and the“targeter” are linked together, e.g., by intervening nucleotides). Thus, for example, a Cas9 guide RNA (dgRNA or sgRNA) comprises a targeting segment (which includes nucleotides that hybridize with (are complementary to) a target nucleic acid, and a duplex-forming segment (e.g., a duplex forming segment of a crRNA, which can also be referred to as a crRNA repeat). Because the sequence of a targeting segment (the segment that hybridizes with a target sequence of a target nucleic acid) of a targeter is modified by a user to hybridize with a desired target nucleic acid, the sequence of a targeter will often be a non- naturally occurring sequence. However, the duplex-forming segment of a targeter (described in more detail below), which hybridizes with the duplex-forming segment of an activator, can include a naturally existing sequence (e.g., can include the sequence of a duplex-forming segment of a naturally existing crRNA, which can also be referred to as a crRNA repeat). Thus, the term targeter is used herein to distinguish from naturally occurring crRNAs, despite the fact that part of a targeter (e.g., the duplex-forming segment) often includes a naturally occurring sequence from a crRNA. However, the term“targeter” encompasses naturally occurring crRNAs.

[00174] A Cas9 guide RNA can also be said to include 3 parts: (i) a targeting sequence (a

nucleotide sequence that hybridizes with a sequence of the target nucleic acid); (ii) an activator sequence (as described above)(in some cases, referred to as a tracr sequence); and (iii) a sequence that hybridizes to at least a portion of the activator sequence to form a double stranded duplex. A targeter has (i) and (iii); while an activator has (ii).

[00175] A Cas9 guide RNA (e.g. a dual guide RNA or a single guide RNA) can be comprised of any corresponding activator and targeter pair. In some cases, the duplex forming segments can be swapped between the activator and the targeter. In other words, in some cases, the targeter includes a sequence of nucleotides from a duplex forming segment of a tracrRNA (which sequence would normally be part of an activator) while the activator includes a sequence of nucleotides from a duplex forming segment of a crRNA (which sequence would normally be part of a targeter).

[00176] As noted above, a targeter comprises both the targeting segment (single stranded) of the

Cas9 guide RNA and a stretch (“duplex-forming segment”) of nucleotides that forms one half of the dsRNA duplex of the protein-binding segment of the Cas9 guide RNA. A corresponding tracrRNA-like molecule (activator) comprises a stretch of nucleotides (a duplex-forming segment) that forms the other half of the dsRNA duplex of the protein-binding segment of the Cas9 guide RNA. In other words, a stretch of nucleotides of the targeter is complementary to and hybridizes with a stretch of nucleotides of the activator to form the dsRNA duplex of the protein binding segment of a Cas9 guide RNA. As such, each targeter can be said to have a

corresponding activator (which has a region that hybridizes with the targeter). The targeter molecule additionally provides the targeting segment. Thus, a targeter and an activator (as a corresponding pair) hybridize to form a Cas9 guide RNA. The particular sequence of a given naturally existing crRNA or tracrRNA molecule is characteristic of the species in which the RNA molecules are found. Examples of suitable activator and targeter are well known in the art. Targeting segment of a Cas9 guide RNA

[00177] The first segment of a subject guide nucleic acid includes a guide sequence (i.e., a

targeting sequence) (a nucleotide sequence that is complementary to a sequence (a target site) in a target nucleic acid). In other words, the targeting segment of a subject guide nucleic acid can interact with a target nucleic acid (e.g., double stranded DNA (dsDNA)) in a sequence-specific manner via hybridization (i.e., base pairing). As such, the nucleotide sequence of the targeting segment may vary (depending on the target) and can determine the location within the target nucleic acid that the Cas9 guide RNA and the target nucleic acid will interact. The targeting segment of a Cas9 guide RNA can be modified (e.g., by genetic engineering)/designed to hybridize to any desired sequence (target site) within a target nucleic acid (e.g., a eukaryotic target nucleic acid such as genomic DNA).

[00178] The targeting segment can have a length of 7 or more nucleotides (nt) (e.g., 8 or more, 9 or more, 10 or more, 12 or more, 15 or more, 20 or more, 25 or more, 30 or more, or 40 or more nucleotides). In some cases, the targeting segment can have a length of from 7 to 100 nucleotides (nt) (e.g., from 7 to 80 nt, from 7 to 60 nt, from 7 to 40 nt, from 7 to 30 nt, from 7 to 25 nt, from

7 to 22 nt, from 7 to 20 nt, from 7 to 18 nt, from 8 to 80 nt, from 8 to 60 nt, from 8 to 40 nt, from

8 to 30 nt, from 8 to 25 nt, from 8 to 22 nt, from 8 to 20 nt, from 8 to 18 nt, from 10 to 100 nt, from 10 to 80 nt, from 10 to 60 nt, from 10 to 40 nt, from 10 to 30 nt, from 10 to 25 nt, from 10 to 22 nt, from 10 to 20 nt, from 10 to 18 nt, from 12 to 100 nt, from 12 to 80 nt, from 12 to 60 nt, from 12 to 40 nt, from 12 to 30 nt, from 12 to 25 nt, from 12 to 22 nt, from 12 to 20 nt, from 12 to 18 nt, from 14 to 100 nt, from 14 to 80 nt, from 14 to 60 nt, from 14 to 40 nt, from 14 to 30 nt, from 14 to 25 nt, from 14 to 22 nt, from 14 to 20 nt, from 14 to 18 nt, from 16 to 100 nt, from 16 to 80 nt, from 16 to 60 nt, from 16 to 40 nt, from 16 to 30 nt, from 16 to 25 nt, from 16 to 22 nt, from 16 to 20 nt, from 16 to 18 nt, from 18 to 100 nt, from 18 to 80 nt, from 18 to 60 nt, from 18 to 40 nt, from 18 to 30 nt, from 18 to 25 nt, from 18 to 22 nt, or from 18 to 20 nt).

[00179] The nucleotide sequence (the targeting sequence) of the targeting segment that is

complementary to a nucleotide sequence (target site) of the target nucleic acid can have a length of 10 nt or more. For example, the targeting sequence of the targeting segment that is complementary to a target site of the target nucleic acid can have a length of 12 nt or more, 15 nt or more, 18 nt or more, 19 nt or more, or 20 nt or more. In some cases, the nucleotide sequence (the targeting sequence) of the targeting segment that is complementary to a nucleotide sequence (target site) of the target nucleic acid has a length of 12 nt or more. In some cases, the nucleotide sequence (the targeting sequence) of the targeting segment that is complementary to a nucleotide sequence (target site) of the target nucleic acid has a length of 18 nt or more. [00180] For example, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid can have a length of from 10 to 100 nucleotides (nt) (e.g., from 10 to 90 nt, from 10 to 75 nt, from 10 to 60 nt, from 10 to 50 nt, from 10 to 35 nt, from 10 to 30 nt, from 10 to 25 nt, from 10 to 22 nt, from 10 to 20 nt, from 12 to 100 nt, from 12 to 90 nt, from 12 to 75 nt, from 12 to 60 nt, from 12 to 50 nt, from 12 to 35 nt, from 12 to 30 nt, from 12 to 25 nt, from 12 to 22 nt, from 12 to 20 nt, from 15 to 100 nt, from 15 to 90 nt, from 15 to 75 nt, from 15 to 60 nt, from 15 to 50 nt, from 15 to 35 nt, from 15 to 30 nt, from 15 to 25 nt, from 15 to 22 nt, from 15 to 20 nt, from 17 to 100 nt, from 17 to 90 nt, from 17 to 75 nt, from 17 to 60 nt, from 17 to 50 nt, from 17 to 35 nt, from 17 to 30 nt, from 17 to 25 nt, from 17 to 22 nt, from 17 to 20 nt, from 18 to 100 nt, from 18 to 90 nt, from 18 to 75 nt, from 18 to 60 nt, from 18 to 50 nt, from 18 to 35 nt, from 18 to 30 nt, from 18 to 25 nt, from 18 to 22 nt, or from 18 to 20 nt). In some cases, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid has a length of from 15 nt to 30 nt. In some cases, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid has a length of from 15 nt to 25 nt. In some cases, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid has a length of from 18 nt to 30 nt. In some cases, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid has a length of from 18 nt to 25 nt. In some cases, the targeting sequence of the targeting segment that is complementary to a target sequence of the target nucleic acid has a length of from 18 nt to 22 nt. In some cases, the targeting sequence of the targeting segment that is complementary to a target site of the target nucleic acid is 20 nucleotides in length. In some cases, the targeting sequence of the targeting segment that is complementary to a target site of the target nucleic acid is 19 nucleotides in length.

[00181] The percent complementarity between the targeting sequence (guide sequence) of the targeting segment and the target site of the target nucleic acid can be 60% or more (e.g., 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 97% or more, 98% or more, 99% or more, or 100%). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the seven contiguous 5’-most nucleotides of the target site of the target nucleic acid. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 60% or more over about 20 contiguous nucleotides. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the fourteen contiguous 5’-most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 14 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the seven contiguous 5’-most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 20 nucleotides in length.

[00182] In some cases, the percent complementarity between the targeting sequence of the

targeting segment and the target site of the target nucleic acid is 100% over the 7 contiguous 5’- most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’-most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 8 contiguous 5’-most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’-most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 9 contiguous 5’-most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’-most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 10 contiguous 5’-most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’-most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 17 contiguous 5’-most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’- most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 18 contiguous 5’-most nucleotides of the target site of the target nucleic acid (which can be complementary to the 3’-most nucleotides of the targeting sequence of the Cas9 guide RNA). In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 60% or more (e.g., e.g., 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 97% or more, 98% or more, 99% or more, or 100%) over about 20 contiguous nucleotides.

[00183] In some cases, the percent complementarity between the targeting sequence of the

targeting segment and the target site of the target nucleic acid is 100% over the 7 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 7 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 8 contiguous 5’-most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 8 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 9 contiguous 5’-most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 9 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 10 contiguous 5’-most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 10 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 11 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 11 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 12 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 12 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 13 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 13 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 14 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 14 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 17 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 17 nucleotides in length. In some cases, the percent complementarity between the targeting sequence of the targeting segment and the target site of the target nucleic acid is 100% over the 18 contiguous 5’- most nucleotides of the target site of the target nucleic acid and as low as 0% or more over the remainder. In such a case, the targeting sequence can be considered to be 18 nucleotides in length.

[00184] Examples of various Cas9 proteins and Cas9 guide RNAs (as well as information

regarding requirements related to protospacer adjacent motif (PAM) sequences present in targeted nucleic acids) can be found in the art, for example, see Jinek et al., Science. 2012 Aug 17;337(6096):816-21; Chylinski et al., RNA Biol. 2013 May;l0(5):726-37; Ma et al., Biomed Res Int. 20l3;20l3:270805; Hou et al., Proc Natl Acad Sci U S A. 2013 Sep 24;l l0(39):l5644- 9; Jinek et al., Elife. 20l3;2:e0047l; Pattanayak et al., Nat Biotechnol. 2013 Sep;3l(9):839-43; Qi et al, Cell. 2013 Feb 28;l52(5): 1173-83; Wang et al., Cell. 2013 May 9;153(4):910-8; Auer et al., Genome Res. 2013 Oct 31; Chen et al., Nucleic Acids Res. 2013 Nov l;4l(20):el9; Cheng et al., Cell Res. 2013 Oct;23(lO):l l63-7l; Cho et al., Genetics. 2013 Nov;l95(3):l l77-80; DiCarlo et al., Nucleic Acids Res. 2013 Apr;4l(7):4336-43; Dickinson et al., Nat Methods. 2013 Oct;l0(l0):l028-34; Ebina et al., Sci Rep. 20l3;3:25l0; Fujii et al., Nucleic Acids Res. 2013 Nov l;4l(20):el87; Hu et al., Cell Res. 2013 Nov;23(l l): 1322-5; Jiang et al., Nucleic Acids Res. 2013 Nov 1 ;41(20):el88; Larson et al., Nat Protoc. 2013 Nov;8(l l):2l80-96; Mali et al., Nat Methods. 2013 Oct;lO(lO):957-63; Nakayama et al., Genesis. 2013 Dec;5l(l2):835-43; Ran et al., Nat Protoc. 2013 Nov;8(ll):228l-308; Ran et al., Cell. 2013 Sep 12;154(6):1380-9;

Upadhyay et al., G3 (Bethesda). 2013 Dec 9;3(l2):2233-8; Walsh et al., Proc Natl Acad Sci U S A. 2013 Sep 24;110(39):15514-5; Xie et al., Mol Plant. 2013 Oct 9; Yang et al., Cell. 2013 Sep 12;154(6):1370-9; Briner et al., Mol Cell. 2014 Oct 23;56(2):333-9; and U.S. patents and patent applications: 8,906,616; 8,895,308; 8,889,418; 8,889,356; 8,871,445; 8,865,406; 8,795,965; 8,771,945; 8,697,359; 20140068797; 20140170753; 20140179006; 20140179770;

20140186843; 20140186919; 20140186958; 20140189896; 20140227787; 20140234972;

20140242664; 20140242699; 20140242700; 20140242702; 20140248702; 20140256046;

20140273037; 20140273226; 20140273230; 20140273231; 20140273232; 20140273233;

20140273234; 20140273235; 20140287938; 20140295556; 20140295557; 20140298547;

20140304853; 20140309487; 20140310828; 20140310830; 20140315985; 20140335063;

20140335620; 20140342456; 20140342457; 20140342458; 20140349400; 20140349405;

20140356867; 20140356956; 20140356958; 20140356959; 20140357523; 20140357530;

20140364333; and 20140377868; all of which are hereby incorporated by reference in their entirety.

[00185] In some cases, a Cas9 guide RNA comprises has one or more modifications, e.g., a base modification, a backbone modification, etc. Suitable nucleic acid modifications include, but are not limited to: 2’0-methyl modified nucleotides, 2’ Fluoro modified nucleotides, locked nucleic acid (LNA) modified nucleotides, peptide nucleic acid (PNA) modified nucleotides, nucleotides with phosphorothioate linkages, and a 5’ cap (e.g., a 7-methylguanylate cap (m7G)).

[00186] Suitable modified oligonucleotide backbones containing a phosphorus atom therein include, for example, phosphorothioates, chiral phosphorothioates, phosphorodithioates, phosphotriesters, aminoalkylphosphotriesters, methyl and other alkyl phosphonates including 3'- alkylene phosphonates, 5'-alkylene phosphonates and chiral phosphonates, phosphinates, phosphoramidates including 3'-amino phosphoramidate and aminoalkylphosphoramidates, phosphorodiamidates , thionophosphoramidates , thionoalkylphosphonates ,

thionoalkylphosphotriesters, selenophosphates and boranophosphates having normal 3'-5' linkages, 2'-5' linked analogs of these, and those having inverted polarity wherein one or more internucleotide linkages is a 3' to 3', 5' to 5' or 2' to 2' linkage. Suitable oligonucleotides having inverted polarity comprise a single 3' to 3' linkage at the 3'-most internucleotide linkage i.e. a single inverted nucleoside residue which may be a basic (the nucleobase is missing or has a hydroxyl group in place thereof). Various salts (such as, for example, potassium or sodium), mixed salts and free acid forms are also included.

[00187] In some cases, a Cas9 guide RNA comprises a sugar substituent group selected from:

OH; F; 0-, S-, or N-alkyl; 0-, S-, or N-alkenyl; 0-, S- or N-alkynyl; or O-alkyl-O-alkyl, wherein the alkyl, alkenyl and alkynyl may be substituted or unsubstituted C.sub.l to Cio alkyl or C2 to C10 alkenyl and alkynyl. Particularly suitable are 0((CH ₂ ) _n O) _m CH3, 0(CH ₂ ) _n 0CH ₃ ,

0(CH ₂ ) _n NH ₂ , 0(CH ₂ ) _n CH ₃ , 0(CH ₂ ) _n 0NH ₂ , and 0(CH ₂ ) _n ON((CH ₂ ) _n CH ₃ ) ₂ , where n and m are from 1 to about 10. Other suitable modifications include a sugar substituent group selected from: Ci to Cio lower alkyl, substituted lower alkyl, alkenyl, alkynyl, alkaryl, aralkyl, O-alkaryl or O- ar alkyl, SH, SCH ₃ , OCN, Cl, Br, CN, CF ₃ , OCF ₃ , SOCH ₃ , SO2CH3, ON0 ₂ , N0 ₂ , N ₃ , NH ₂ , heterocycloalkyl, heterocycloalkaryl, aminoalkylamino, polyalkylamino, substituted silyl, an RNA cleaving group, a reporter group, an intercalator, a group for improving the

pharmacokinetic properties of an oligonucleotide, or a group for improving the

pharmacodynamic properties of an oligonucleotide, and other substituents having similar properties. A suitable modification includes 2'-methoxyethoxy (2'-0-CH ₂ CH2OCH3, also known as 2'-0-(2-methoxyethyl) or 2'-MOE) (Martin et al., Helv. Chim. Acta, 1995, 78, 486-504, the disclosure of which is incorporated herein by reference in its entirety) i.e., an alkoxyalkoxy group. A further suitable modification includes 2'-dimethylaminooxyethoxy, i.e., a

0(CH ₂ ) ₂ 0N(CH ₃ ) ₂ group, also known as 2'-DMAOE, as described in examples hereinbelow, and 2'-dimethylaminoethoxyethoxy (also known in the art as 2'-0-dimethyl-amino-ethoxy-ethyl or 2'-DMAEOE), i.e., 2’-0-CH ₂ -0-CH ₂ -N(CH ₃ ) ₂ . [00188] A subject nucleic acid may also include nucleobase (often referred to in the art simply as "base") modifications or substitutions. As used herein, "unmodified" or "natural" nucleobases include the purine bases adenine (A) and guanine (G), and the pyrimidine bases thymine (T), cytosine (C) and uracil (U). Modified nucleobases include other synthetic and natural nucleobases such as 5-methylcytosine (5-me-C), 5 -hydroxymethyl cytosine, xanthine, hypoxanthine, 2-aminoadenine, 6-methyl and other alkyl derivatives of adenine and guanine, 2- propyl and other alkyl derivatives of adenine and guanine, 2-thiouracil, 2-thiothymine and 2- thiocytosine, 5-halouracil and cytosine, 5-propynyl (-C=C-CH3) uracil and cytosine and other alkynyl derivatives of pyrimidine bases, 6-azo uracil, cytosine and thymine, 5-uracil

(pseudouracil), 4-thiouracil, 8-halo, 8-amino, 8-thiol, 8-thioalkyl, 8-hydroxyl and other 8- substituted adenines and guanines, 5-halo particularly 5-bromo, 5-trifluoromethyl and other 5- substituted uracils and cytosines, 7-methylguanine and 7-methyladenine, 2-F-adenine, 2-amino- adenine, 8-azaguanine and 8-azaadenine, 7-deazaguanine and 7-deazaadenine and 3- deazaguanine and 3-deazaadenine. Further modified nucleobases include tricyclic pyrimidines such as phenoxazine cytidine(lH-pyrimido(5,4-b)(l,4)benzoxazin-2(3H)-one), phenothiazine cytidine (lH-pyrimido(5,4-b)(l,4)benzothiazin-2(3H)-one), G-clamps such as a substituted phenoxazine cytidine (e.g. 9-(2-aminoethoxy)-H-pyrimido(5,4-(b) (l,4)benzoxazin-2(3H)-one), carbazole cytidine (2H-pyrimido(4,5-b)indol-2-one), pyridoindole cytidine (H- pyrido(3',2':4,5)pyrrolo(2,3-d)pyrimidin-2-one).

METHODS

[00189] The present disclosure provides methods of inhibiting activity of a Cas9 polypeptide.

The methods generally involve contacting the Cas9 polypeptide with: a) an AcrIIA7 polypeptide of the present disclosure; b) an AcrIIA7 fusion polypeptide of the present disclosure; or b) a modified AcrIIA7 polypeptide of the present disclosure. In some cases, the contacting occurs in a living cell in vitro. In some cases, the contacting occurs in a living cell in vivo. In some cases, the contacting occurs outside of a cell in vivo (e.g., the contacting occurs in an extracellular fluid in vivo). For simplicity, unless stated otherwise, an“AcrIIA7 polypeptide of the present disclosure” includes an unmodified AcrIIA7 polypeptide, a variant AcrIIA7 polypeptide (as described above), an AcrIIA7 fusion polypeptide of the present disclosure, and a modified AcrIIA7 polypeptide of the present disclosure.

[00190] A method of the present disclosure can inhibit binding and/or cleavage activity of a

Cas9/guide RNA complex by at least 50%, at least 60%, at least 70%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99%, compared to the binding and/or cleavage activity of the Cas9/guide RNA complex in the absence of the AcrIIA7 polypeptide (i.e., where the Cas9/guide RNA complex is not contacted with the AcrIIA7 polypeptide). [00191] In some cases, a method of the present disclosure comprises introducing into a cell (a

“target cell”) a nucleic acid (e.g., a recombinant expression vector; an mRNA; and the like) comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure, where the cell comprises, at the time the AcrIIA7-encoding nucleic acid is introduced into the cell, a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide) or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide. In some cases, the AcrIIA7-encoding nucleotide sequence is integrated into the genome of the cell. In some cases, the AcrIIA7-encoding nucleotide sequence is extrachromosomal.

[00192] In some cases, a method of the present disclosure comprises introducing into a cell (a

“target cell”) a nucleic acid (e.g., a recombinant expression vector; an mRNA; and the like) comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure, where the cell does not comprise, at the time the AcrIIA7-encoding nucleic acid is introduced into the cell, a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide) or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide. In some cases, the AcrIIA7-encoding nucleotide sequence is integrated into the genome of the cell. In some cases, the AcrIIA7-encoding nucleotide sequence is

extrachromosomal.

[00193] In some cases, a method of the present disclosure comprises introducing into a cell (a

“target cell”) an AcrIIA7 polypeptide of the present disclosure, where the cell comprises, at the time the AcrIIA7 polypeptide is introduced into the cell, a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide) or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide.

[00194] In some cases, a method of the present disclosure comprises introducing into a cell (a

“target cell”) an AcrIIA7 polypeptide of the present disclosure, where the cell does not comprise, at the time the AcrIIA7 polypeptide is introduced into the cell, a Cas9 polypeptide (where the Cas9 polypeptide is one that can be inhibited by the AcrIIA7 polypeptide) or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide.

[00195] Where a method of the present disclosure comprises introducing into a cell a nucleic acid (e.g., a DNA; a recombinant expression vector; an RNA) comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure, in some cases, the AcrIIA7-encoding nucleotide sequence is operably linked to one or more transcriptional control elements. In some cases, the one or more transcriptional control elements comprises a promoter, e.g., a promoter that is functional in a eukaryotic cell. In some cases, the promoter is a constitutive promoter. In some cases, the promoter is a regulated promoter, e.g., an inducible promoter. In some case, the inducible promoter is a drug-inducible promoter, and the method comprises contacting the cell with a drug that induces the drug-inducible promoter.

[00196] In some cases, a method of the present disclosure provides for controlling gene drive.

For example, where the gene drive limits viability of a target organism (or target population of an organism), a method of the present disclosure can restore viability to the target organism (or target population of an organism). Examples of target organisms (or target populations of an organism) include ticks (e.g., ticks that carry human pathogens), where ticks include ticks of the families Ixodidae and Argasidae, e.g., Ixodes ricinus, I. rubicundus, I. scapularis, I. holocyclus, and 7. pacificus mites; mosquitoes (e.g., mosquitoes that carry human pathogens such as malaria parasites, Yellow Fever Virus, Dengue virus, Zika virus, Chikungunya virus, and the like), where examples of such mosquitoes include mosquitoes of the genera Culex, Culistea, Aedes, or Anopheles, e.g., Aedes aegypti, Aedes albopictus, and Anopheles garniae protozoans such as Plasmodium species (e.g., Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, Plasmodium berghei, Plasmodium gallinaceum, and Plasmodium knowlesi), nematode species, Trypanosoma species, Trichomonadidae species, Leishmania species, and the like; insects that are harmful to plants; arthropods that are harmful to plants; and the like.

[00197] In some cases, a method of the present disclosure provides for reducing off-target

CasSVguide RNA-mediated gene editing. In some cases, a method of the present disclosure reduces off-target CasSVguide RNA-mediated gene editing by at least 10%, at least 15%, at least 20%, at least 25%, at least 50%, at least 75%, at least 80%, at least 90%, or more than 95%, compared to the extent of off-target Cas9/guide RNA-mediated gene editing when the Cas9 is not contacted with an AcrIIA7 polypeptide of the present disclosure.

[00198] In some cases, a method of the present disclosure provides protection against deleterious effects of a“hostile” Cas9/guide RNA. For example, an individual can comprise immune cells genetically modified to include an AcrIIA7-encoding nucleic acid; if such an individual comes into contact with a hostile Cas9/guide RNA complex that targets immune cells in a deleterious manner, such an individual can be protected from deleterious effects of such a hostile Cas9/guide RNA.

[00199] In some cases, an AcrIIA7 polypeptide of the present disclosure is used to deliver a Cas9 polypeptide to a cell, e.g., a eukaryotic cell. For example, in some cases, a complex of an AcrIIA7 polypeptide and a Cas9 polypeptide is delivered to a cell. The complex may further include a Cas9 guide RNA and/or a donor template. Target nucleic acids and cells

[00200] An AcrIIA7 polypeptide of the present disclosure inhibits a Cas9 polypeptide (when the

Cas9 polypeptide is complexed with a Cas9 guide RNA) from binding and/or cleaving a target nucleic acid target nucleic acid can be any nucleic acid (e.g., DNA, RNA), can be double stranded or single stranded, can be any type of nucleic acid (e.g., a chromosome (genomic DNA), derived from a chromosome, chromosomal DNA, plasmid, viral, extracellular, intracellular, mitochondrial, chloroplast, linear, circular, etc.) and can be from any organism (e.g., as long as the Cas9 guide RNA comprises a nucleotide sequence that hybridizes to a target sequence in a target nucleic acid, such that the target nucleic acid can be targeted).

[00201] A target nucleic acid (a target of a Cas9/guide RNA complex) can be DNA or RNA. A target nucleic acid can be double stranded (e.g., dsDNA, dsRNA) or single stranded (e.g., ssRNA, ssDNA). In some cases, a target nucleic acid is single stranded. In some cases, a target nucleic acid is a single stranded RNA (ssRNA). In some cases, a target ssRNA (e.g., a target cell ssRNA, a viral ssRNA, etc.) is selected from: mRNA, rRNA, tRNA, non-coding RNA (ncRNA), long non-coding RNA (lncRNA), and microRNA (miRNA). In some cases, a target nucleic acid is a single stranded DNA (ssDNA) (e.g., a viral DNA). As noted above, in some cases, a target nucleic acid is single stranded.

[00202] A target nucleic acid can be located anywhere, for example, outside of a cell in vitro, inside of a cell in vitro, inside of a cell in vivo, inside of a cell ex vivo. Suitable target cells (which can comprise target nucleic acids such as genomic DNA) include, but are not limited to: a bacterial cell; an archaeal cell; a cell of a single-cell eukaryotic organism; a plant cell; an algal cell, e.g., Botryococcus braunii, Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens, C. agardh, and the like; a fungal cell (e.g., a yeast cell); an animal cell; a cell from an invertebrate animal (e.g. fruit fly, a cnidarian, an echinoderm, a nematode, etc.); a cell of an insect (e.g., a mosquito; a bee; an agricultural pest; etc.); a cell of an arachnid (e.g., a spider; a tick; etc.); a cell from a vertebrate animal (e.g., a fish, an amphibian, a reptile, a bird, a mammal); a cell from a mammal (e.g., a cell from a rodent; a cell from a human; a cell of a non-human mammal; a cell of a rodent (e.g., a mouse, a rat); a cell of a lagomorph (e.g., a rabbit); a cell of an ungulate (e.g., a cow, a horse, a camel, a llama, a vicuna, a sheep, a goat, etc.); a cell of a marine mammal (e.g., a whale, a seal, an elephant seal, a dolphin, a sea lion; etc.) and the like. Any type of cell may be of interest (e.g. a stem cell, e.g. an embryonic stem (ES) cell, an induced pluripotent stem (iPS) cell, a germ cell (e.g., an oocyte, a sperm, an oogonia, a spermatogonia, etc.), an adult stem cell, a somatic cell, e.g. a fibroblast, a hematopoietic cell, a neuron, a muscle cell, a bone cell, a hepatocyte, a pancreatic cell; an in vitro or in vivo embryonic cell of an embryo at any stage, e.g., a l-cell, 2-cell, 4-cell, 8-cell, etc. stage zebrafish embryo; etc.).

[00203] Cells may be from established cell lines or they may be primary cells, where“primary cells”,“primary cell lines”, and“primary cultures” are used interchangeably herein to refer to cells and cells cultures that have been derived from a subject and allowed to grow in vitro for a limited number of passages, i.e. splittings, of the culture. For example, primary cultures are cultures that may have been passaged 0 times, 1 time, 2 times, 4 times, 5 times, 10 times, or 15 times, but not enough times go through the crisis stage. Typically, the primary cell lines are maintained for fewer than 10 passages in vitro. Target cells can be unicellular organisms and/or can be grown in culture. If the cells are primary cells, they may be harvest from an individual by any convenient method. For example, leukocytes may be conveniently harvested by apheresis, leukocytapheresis, density gradient separation, etc., while cells from tissues such as skin, muscle, bone marrow, spleen, liver, pancreas, lung, intestine, stomach, etc. can be conveniently harvested by biopsy.

[00204] Plant cells include cells of a monocotyledon, and cells of a dicotyledon. The cells can be root cells, leaf cells, cells of the xylem, cells of the phloem, cells of the cambium, apical meristem cells, parenchyma cells, collenchyma cells, sclerenchyma cells, and the like. Plant cells include cells of agricultural crops such as wheat, corn, rice, sorghum, millet, soybean, etc. Plant cells include cells of agricultural fruit and nut plants, e.g., plant that produce apricots, oranges, lemons, apples, plums, pears, almonds, etc.

[00205] Additional examples of target cells are listed above in the section titled“Modified cells.”

Non-limiting examples of cells (target cells) include: a prokaryotic cell, eukaryotic cell, a bacterial cell, an archaeal cell, a cell of a single-cell eukaryotic organism, a protozoa cell, a cell from a plant (e.g., cells from plant crops, fruits, vegetables, grains, soy bean, corn, maize, wheat, seeds, tomatoes, rice, cassava, sugarcane, pumpkin, hay, potatoes, cotton, cannabis, tobacco, flowering plants, conifers, gymnosperms, angiosperms, ferns, clubmosses, hornworts, liverworts, mosses, dicotyledons, monocotyledons, etc.), an algal cell, (e.g., Botryococcus braunii,

Chlamydomonas reinhardtii, Nannochloropsis gaditana, Chlorella pyrenoidosa, Sargassum patens, C. agardh, and the like), seaweeds (e.g. kelp) a fungal cell (e.g., a yeast cell, a cell from a mushroom), an animal cell, a cell from an invertebrate animal (e.g., fruit fly, cnidarian, echinoderm, nematode, etc.), a cell from a vertebrate animal (e.g., fish, amphibian, reptile, bird, mammal), a cell from a mammal (e.g., an ungulate (e.g., a pig, a cow, a goat, a sheep); a rodent (e.g., a rat, a mouse); a non-human primate; a human; a feline (e.g., a cat); a canine (e.g., a dog); etc.), and the like. In some cases, the cell is a cell that does not originate from a natural organism (e.g., the cell can be a synthetically made cell; also referred to as an artificial cell). [00206] A cell can be an in vitro cell (e.g., established cultured cell line). A cell can be an ex vivo cell (cultured cell from an individual). A cell can be and in vivo cell (e.g., a cell in an individual). A cell can be an isolated cell. A cell can be a cell inside of an organism. A cell can be an organism. A cell can be a cell in a cell culture (e.g., in vitro cell culture). A cell can be one of a collection of cells. A cell can be a prokaryotic cell or derived from a prokaryotic cell. A cell can be a bacterial cell or can be derived from a bacterial cell. A cell can be an archaeal cell or derived from an archaeal cell. A cell can be a eukaryotic cell or derived from a eukaryotic cell. A cell can be a plant cell or derived from a plant cell. A cell can be an animal cell or derived from an animal cell. A cell can be an invertebrate cell or derived from an invertebrate cell. A cell can be a vertebrate cell or derived from a vertebrate cell. A cell can be a mammalian cell or derived from a mammalian cell. A cell can be a rodent cell or derived from a rodent cell. A cell can be a human cell or derived from a human cell. A cell can be a microbe cell or derived from a microbe cell. A cell can be a fungi cell or derived from a fungi cell. A cell can be an insect cell. A cell can be an arthropod cell. A cell can be a protozoan cell. A cell can be a helminth cell.

[00207] Suitable cells include a stem cell (e.g. an embryonic stem (ES) cell, an induced

pluripotent stem (iPS) cell; a germ cell (e.g., an oocyte, a sperm, an oogonia, a spermatogonia, etc.); a somatic cell, e.g. a fibroblast, an oligodendrocyte, a glial cell, a hematopoietic cell, a neuron, a muscle cell, a bone cell, a hepatocyte, a pancreatic cell, etc.

[00208] Suitable cells include human embryonic stem cells, fetal cardiomyocytes,

myofibroblasts, mesenchymal stem cells, adult cardiomyocytes, adipocytes, totipotent cells, pluripotent cells, blood stem cells, myoblasts, adult stem cells, bone marrow cells, mesenchymal cells, embryonic stem cells, parenchymal cells, epithelial cells, endothelial cells, mesothelial cells, fibroblasts, osteoblasts, chondrocytes, exogenous cells, endogenous cells, stem cells, hematopoietic stem cells, bone-marrow derived progenitor cells, myocardial cells, skeletal cells, fetal cells, undifferentiated cells, multi-potent progenitor cells, unipotent progenitor cells, monocytes, cardiac myoblasts, skeletal myoblasts, macrophages, capillary endothelial cells, xenogenic cells, allogenic cells, and post-natal stem cells.

[00209] In some cases, the cell is an immune cell, a neuron, an epithelial cell, and endothelial cell, or a stem cell. In some cases, the immune cell is a T cell, a B cell, a monocyte, a natural killer cell, a dendritic cell, or a macrophage. In some cases, the immune cell is a cytotoxic T cell. In some cases, the immune cell is a helper T cell. In some cases, the immune cell is a regulatory T cell (Treg).

[00210] In some cases, the cell is a stem cell. Stem cells include adult stem cells. Adult stem cells are also referred to as somatic stem cells. [00211] Adult stem cells are resident in differentiated tissue, but retain the properties of self renewal and ability to give rise to multiple cell types, usually cell types typical of the tissue in which the stem cells are found. Numerous examples of somatic stem cells are known to those of skill in the art, including muscle stem cells; hematopoietic stem cells; epithelial stem cells; neural stem cells; mesenchymal stem cells; mammary stem cells; intestinal stem cells;

mesodermal stem cells; endothelial stem cells; olfactory stem cells; neural crest stem cells; and the like.

[00212] Stem cells of interest include mammalian stem cells, where the term“mammalian”

refers to any animal classified as a mammal, including humans; non-human primates; domestic and farm animals; and zoo, laboratory, sports, or pet animals, such as dogs, horses, cats, cows, mice, rats, rabbits, etc. In some cases, the stem cell is a human stem cell. In some cases, the stem cell is a rodent (e.g., a mouse; a rat) stem cell. In some cases, the stem cell is a non-human primate stem cell.

[00213] Stem cells can express one or more stem cell markers, e.g., SOX9, KRT19, KRT7,

LGR5, CA9, FXYD2, CDH6, CLDN18, TSPAN8, BPIFB1, OLFM4, CDH17, and PPARGC1A.

[00214] In some embodiments, the stem cell is a hematopoietic stem cell (HSC). HSCs are

mesoderm-derived cells that can be isolated from bone marrow, blood, cord blood, fetal liver and yolk sac. HSCs are characterized as CD34+ and CD3-. HSCs can repopulate the erythroid, neutrophil-macrophage, megakaryocyte and lymphoid hematopoietic cell lineages in vivo. In vitro, HSCs can be induced to undergo at least some self-renewing cell divisions and can be induced to differentiate to the same lineages as is seen in vivo. As such, HSCs can be induced to differentiate into one or more of erythroid cells, megakaryocytes, neutrophils, macrophages, and lymphoid cells.

[00215] In other embodiments, the stem cell is a neural stem cell (NSC). Neural stem cells

(NSCs) are capable of differentiating into neurons, and glia (including oligodendrocytes, and astrocytes). A neural stem cell is a multipotent stem cell which is capable of multiple divisions, and under specific conditions can produce daughter cells which are neural stem cells, or neural progenitor cells that can be neuroblasts or glioblasts, e.g., cells committed to become one or more types of neurons and glial cells respectively. Methods of obtaining NSCs are known in the art.

[00216] In other embodiments, the stem cell is a mesenchymal stem cell (MSC). MSCs

originally derived from the embryonal mesoderm and isolated from adult bone marrow, can differentiate to form muscle, bone, cartilage, fat, marrow stroma, and tendon. Methods of isolating MSC are known in the art; and any known method can be used to obtain MSC. See, e.g., U.S. Pat. No. 5,736,396, which describes isolation of human MSC.

[00217] A cell is in some cases a plant cell. A plant cell can be a cell of a monocotyledon. A cell can be a cell of a dicotyledon.

[00218] In some cases, the cell is a plant cell. For example, the cell can be a cell of a major

agricultural plant, e.g., Barley, Beans (Dry Edible), Canola, Corn, Cotton (Pima), Cotton (Upland), Flaxseed, Hay (Alfalfa), Hay (Non- Alfalfa), Oats, Peanuts, Rice, Sorghum, Soybeans, Sugarbeets, Sugarcane, Sunflowers (Oil), Sunflowers (Non-Oil), Sweet Potatoes , Tobacco (Burley), Tobacco (Flue-cured), Tomatoes, Wheat (Durum), Wheat (Spring), Wheat (Winter), and the like. As another example, the cell is a cell of a vegetable crops which include but are not limited to, e.g., alfalfa sprouts, aloe leaves, arrow root, arrowhead, artichokes, asparagus, bamboo shoots, banana flowers, bean sprouts, beans, beet tops, beets, bittermelon, bok choy, broccoli, broccoli rabe (rappini), brussels sprouts, cabbage, cabbage sprouts, cactus leaf

(nopales), calabaza, cardoon, carrots, cauliflower, celery, chayote, Chinese artichoke (crosnes), Chinese cabbage, Chinese celery, Chinese chives, choy sum, chrysanthemum leaves (tung ho), collard greens, corn stalks, corn-sweet, cucumbers, daikon, dandelion greens, dasheen, dau mue (pea tips), donqua (winter melon), eggplant, endive, escarole, fiddle head ferns, field cress, frisee, gai choy (Chinese mustard), gallon, galanga (siam, thai ginger), garlic, ginger root, gobo, greens, hanover salad greens, huauzontle, jerusalem artichokes, jicama, kale greens, kohlrabi, lamb's quarters (quilete), lettuce (bibb), lettuce (boston), lettuce (boston red), lettuce (green leaf), lettuce (iceberg), lettuce (lolla rossa), lettuce (oak leaf - green), lettuce (oak leaf - red), lettuce (processed), lettuce (red leaf), lettuce (romaine), lettuce (ruby romaine), lettuce (russian red mustard), linkok, lo bok, long beans, lotus root, mache, maguey (agave) leaves, malanga, mesculin mix, mizuna, moap (smooth luffa), moo, moqua (fuzzy squash), mushrooms, mustard, nagaimo, okra, ong choy, onions green, opo (long squash), ornamental corn, ornamental gourds, parsley, parsnips, peas, peppers (bell type), peppers, pumpkins, radicchio, radish sprouts, radishes, rape greens, rape greens, rhubarb, romaine (baby red), rutabagas, salicornia (sea bean), sinqua (angled/ridged luffa), spinach, squash, straw bales, sugarcane, sweet potatoes, swiss chard, tamarindo, taro, taro leaf, taro shoots, tatsoi, tepeguaje (guaje), tindora, tomatillos, tomatoes, tomatoes (cherry), tomatoes (grape type), tomatoes (plum type), tumeric, turnip tops greens, turnips, water chestnuts, yampi, yams (names), yu choy, yuca (cassava), and the like.

[00219] A cell is in some cases an arthropod cell. For example, the cell can be a cell of a sub order, a family, a sub-family, a group, a sub-group, or a species of, e.g., Chelicerata,

Myriapodia, Hexipodia, Arachnida, Insecta, Archaeognatha, Thysanura, Palaeoptera,

Ephemeroptera, Odonata, Anisoptera, Zygoptera, Neoptera, Exopterygota, Plecoptera , Embioptera , Orthoptera, Zoraptera , Dermaptera, Dictyoptera, Notoptera, Grylloblattidae, Mantophasmatidae, Phasmatodea , Blattaria, Isoptera, Mantodea, Parapneuroptera,

Psocoptera, Thysanoptera, Phthiraptera, Hemiptera, Endopterygota or Holometabola , Hymenoptera , Coleoptera, Strepsiptera, Raphidioptera, Megaloptera, Neuroptera , Mecoptera , Siphonaptera, Diptera, Trichoptera, or Lepidoptera.

[00220] A cell is in some cases an insect cell. For example, in some cases, the cell is a cell of a mosquito, a grasshopper, a true bug, a fly, a flea, a bee, a wasp, an ant, a louse, a moth, or a beetle.

KITS

[00221] The present disclosure provides a kit comprising an AcrIIA7 polypeptide of the present disclosure or a nucleic acid (e.g., a recombinant expression vector) comprising a nucleotide sequence encoding an AcrIIA7 polypeptide of the present disclosure. The present disclosure provides a kit comprising an AcrIIA7 system of the present disclosure or a component of an AcrIIA7 system of the present disclosure.

[00222] A kit of the present can comprise: a) any combination of an AcrIIA7 system, as

described above; b) and one or more additional components and/or reagents, e.g., i) a buffer; ii) a protease inhibitor; iii) a nuclease inhibitor; iv) a positive and/or negative control target DNA; v) a positive and/or negative control Cas9 guide RNA; and the like.

[00223] In some cases, a kit of the present disclosure comprises: a) a Cas9 polypeptide

comprising an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 3, or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide; and b) an AcrIIA7 polypeptide that is an inhibitor of an activity of the Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% (at least 70%, at least 85%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or 100%) amino acid sequence identity to the amino acid sequence depicted in FIG. 1, or a nucleic acid comprising a nucleotide sequence encoding the AcrIIA7 polypeptide, wherein the enzymatic activity is nucleic acid cleavage.

[00224] In some cases, a kit of the present disclosure comprises:

[00225] a) a Cas9 polypeptide comprising an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 3, or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide; and

[00226] b) i) an AcrIIA7 polypeptide that is an inhibitor of an activity of the Cas9 polypeptide; or ii) an AcrIIA7 fusion polypeptide of the present disclosure; or iii) a modified AcrIIA7 polypeptide of the present disclosure, wherein the AcrIIA7 polypeptide (or the AcrIIA7 polypeptide present in the fusion polypeptide, or the modified AcrIIA7 polypeptide)) comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1 ; or iv) a nucleic acid comprising a nucleotide sequence encoding the AcrIIA7 polypeptide; or v) a nucleic acid comprising a nucleotide sequence encoding the AcrIIA7 fusion polypeptide, wherein the enzymatic activity is nucleic acid cleavage.

Examples of Non-Limiting Aspects of the Disclosure

[00227] Aspects, including embodiments, of the present subject matter described above may be beneficial alone or in combination, with one or more other aspects or embodiments. Without limiting the foregoing description, certain non-limiting aspects of the disclosure numbered 1-57 are provided below. As will be apparent to those of skill in the art upon reading this disclosure, each of the individually numbered aspects may be used or combined with any of the preceding or following individually numbered aspects. This is intended to provide support for all such combinations of aspects and is not limited to combinations of aspects explicitly provided below:

[00228] Aspect 1. A fusion polypeptide comprising:

[00229] a) anti-CRISPR (Acr) polypeptide that is an inhibitor of an enzymatic activity of a Cas9 polypeptide, wherein the Acr polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1 ; and

[00230] b) a heterologous fusion partner.

[00231] Aspect 2. The fusion polypeptide of aspect 1 , wherein the heterologous fusion partner is a nuclear localization sequence.

[00232] Aspect 3. The fusion polypeptide of aspect 1, wherein the heterologous fusion partner is an epitope tag.

[00233] Aspect 4. The fusion polypeptide of any one of aspects 1-3, wherein the Acr polypeptide lacks the 50-59 amino-terminal amino acids of the polypeptide depicted in FIG. 1 ; and wherein the Acr polypeptide has a length of from 125 amino acids to 134 amino acids.

[00234] Aspect 5. A nucleic acid comprising a nucleotide sequence encoding the fusion

polypeptide of any one of aspects 1-4.

[00235] Aspect 6. The nucleic acid of aspect 5, wherein the nucleotide sequence is operably linked to a promoter.

[00236] Aspect 7. A recombinant expression vector comprising the nucleic acid of aspect 5 or aspect 6.

[00237] Aspect 8. A cell comprising the nucleic acid of aspect 4 or aspect 5, or the recombinant expression vector of aspect 7.

[00238] Aspect 9. The cell of aspect 8, wherein the cell is a eukaryotic cell. [00239] Aspect 10. The cell of aspect 8 or aspect 9, wherein the cell is in vitro.

[00240] Aspect 11. The cell of aspect 8 or aspect 9, wherein the cell is in vivo.

[00241] Aspect 12. A modified AcrIIA7 polypeptide comprising: a) an AcrIIA7 polypeptide that is an inhibitor of an enzymatic activity of a Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1 ; and b) a non-peptidic moiety covalently linked to the AcrIIA7 polypeptide.

[00242] Aspect 13. The modified AcrIIA7 polypeptide of aspect 12, wherein the non-peptidic moiety provides for one or more of an increase in in vivo half-life, in vivo stability, and bioavailability of the AcrIIA7 polypeptide, compared to the unmodified AcrIIA7 polypeptide.

[00243] Aspect 14. The modified AcrIIA7 polypeptide of aspect 12 or aspect 13, wherein the non-peptidic moiety comprises poly(ethylene glycol).

[00244] Aspect 15. A recombinant expression vector comprising a nucleotide sequence encoding an AcrIIA7 polypeptide that is an inhibitor of an enzymatic activity of a Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1.

[00245] Aspect 16. The recombinant expression vector of aspect 15, wherein the AcrIIA7

polypeptide-encoding nucleotide sequence is operably linked to a promoter.

[00246] Aspect 17. The recombinant expression vector of aspect 16, wherein the promoter is functional in a eukaryotic cell.

[00247] Aspect 18. The recombinant expression vector of aspect 16 or aspect 17, wherein the promoter is a regulated promoter.

[00248] Aspect 19. The recombinant expression vector of aspect 18, wherein the regulated

promoter is an inducible promoter.

[00249] Aspect 20. The recombinant expression vector of aspect 19, wherein the inducible

promoter is a heat-inducible promoter, a drug-inducible promoter, an alcohol-inducible promoter, a hormone-inducible promoter, a steroid-inducible promoter, or a metal-inducible promoter.

[00250] Aspect 21. The recombinant expression vector of aspect 16 or aspect 17, wherein the promoter is a tissue-specific promoter or a cell type-specific promoter.

[00251] Aspect 22. The recombinant expression vector of any one of aspects 15-21, further comprising a nucleotide sequence encoding a guide RNA that binds to and activates a Cas9 polypeptide. [00252] Aspect 23. The recombinant expression vector of any one of aspects 15-22, wherein the recombinant expression vector is a recombinant viral vector.

[00253] Aspect 24. A cell comprising the recombinant expression vector of any one of aspects

15-23.

[00254] Aspect 25. The cell of aspect 24, wherein the cell is in vitro.

[00255] Aspect 26. The cell of aspect 24, wherein the cell is in vivo.

[00256] Aspect 27. The cell of any one of aspects 24-26, wherein the cell is a eukaryotic cell.

[00257] Aspect 28. The cell of aspect 27, wherein the cell is a mammalian cell, an insect cell, a plant cell, an arthropod cell, a helminth cell, a protozoan cell, a reptile cell, an avian cell, an amphibian cell, a fungal cell, an algal cell, or a fish cell.

[00258] Aspect 29. A nucleic acid comprising:

[00259] a) a first nucleotide sequence encoding the constant region of a guide RNA;

[00260] b) a second nucleotide sequence encoding a Cas9 polypeptide; and

[00261] c) a third nucleotide sequence encoding an AcrIIA7 polypeptide that is an inhibitor of the Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1.

[00262] Aspect 30. The nucleic acid of aspect 29, comprising an insertion site for inserting a nucleotide sequence encoding a guide sequence of the guide RNA, wherein the insertion site is 5’ of and immediately adjacent to first nucleotide sequence.

[00263] Aspect 31. The nucleic acid of aspect 29, comprising a nucleotide sequence encoding a guide sequence of the guide RNA, wherein the guide sequence-encoding nucleotide sequence is 5’ of and immediately adjacent to first nucleotide sequence.

[00264] Aspect 32. The nucleic acid of any one of aspects 29-31 , wherein the Cas9 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 3.

[00265] Aspect 33. The nucleic acid of any one of aspects 29-32, wherein the third nucleotide sequence is operably linked to a promoter.

[00266] Aspect 34. The nucleic acid of aspect 33, wherein the promoter is functional in a

eukaryotic cell.

[00267] Aspect 35. The nucleic acid of aspect 33 or aspect 34, wherein the promoter is an

inducible promoter.

[00268] Aspect 36. The nucleic acid of aspect 35, wherein the inducible promoter is a heat- inducible promoter, a drug-inducible promoter, an alcohol-inducible promoter, a hormone- inducible promoter, a steroid-inducible promoter, or a metal-inducible promoter. [00269] Aspect 37. The nucleic acid of aspect 33 or 34, wherein the promoter is a tissue-specific promoter or a cell type-specific promoter.

[00270] Aspect 38. A recombinant expression vector comprising the nucleic acid of any one of aspects 29-37.

[00271] Aspect 39. A cell comprising the nucleic acid of any one of aspects 29-37 or the

recombinant expression vector of aspect 38.

[00272] Aspect 40. The cell of aspect 39, wherein the cell is in vitro.

[00273] Aspect 41. The cell of aspect 39, wherein the cell is in vivo.

[00274] Aspect 42. The cell of any one of aspects 39-41, wherein the cell is a eukaryotic cell.

[00275] Aspect 43. The cell of aspect 42, wherein the cell is a mammalian cell, an insect cell, a plant cell, an arthropod cell, a helminth cell, a protozoan cell, a reptile cell, an avian cell, an amphibian cell, a fungal cell, an algal cell, or a fish cell.

[00276] Aspect 44. A nucleic acid comprising a nucleotide sequence encoding an AcrIIA7 polypeptide that is an inhibitor of an enzymatic activity of a Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1 , and wherein the nucleotide sequence is optimized for expression in a mammalian cell.

[00277] Aspect 45. The nucleic acid of aspect 44, wherein the nucleotide sequence is operably linked to a promoter.

[00278] Aspect 46. A recombinant expression vector comprising the nucleic acid of aspect 44 or aspect 45.

[00279] Aspect 47. A kit comprising:

[00280] a) a Cas9 polypeptide comprising an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 3, or a nucleic acid comprising a nucleotide sequence encoding the Cas9 polypeptide; and

[00281] b) an AcrIIA7 polypeptide that is an inhibitor of an activity of the Cas9 polypeptide, wherein the AcrIIA7 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 1 , or a nucleic acid comprising a nucleotide sequence encoding the AcrIIA7 polypeptide, wherein the enzymatic activity is nucleic acid cleavage.

[00282] Aspect 48. The kit of aspect 47, wherein component (a) and component (b) are in

separate containers.

[00283] Aspect 49. A method for inhibiting an activity of a Cas9 polypeptide, the method

comprising contacting the Cas9 polypeptide with: [00284] a) an AcrIIA7 polypeptide; or

[00285] b) the AcrIIA7 fusion polypeptide of any one of aspects 1-4.

[00286] Aspect 50. The method of aspect 49, wherein the Cas9 polypeptide comprises an amino acid sequence having at least 70% amino acid sequence identity to the amino acid sequence depicted in FIG. 3.

[00287] Aspect 51. The method of aspect 49 or 50, wherein said contacting occurs in a living cell in vitro.

[00288] Aspect 52. The method of aspect 49 or 50, wherein said contacting occurs in a living cell in vivo.

[00289] Aspect 53. The method of aspect 51 or aspect 52, comprising introducing into the cell a nucleic acid comprising a nucleotide sequence encoding the AcrIIA7 polypeptide.

[00290] Aspect 54. The method of aspect 52, wherein the nucleotide sequence encoding the

AcrIIA7 polypeptide is operably linked to an inducible promoter.

[00291] Aspect 55. The method of any one of aspects 51-54, wherein the cell is a eukaryotic cell.

[00292] Aspect 56. The method of aspect 54, wherein the cell is a mammalian cell, an insect cell, a plant cell, an arthropod cell, a helminth cell, a protozoan cell, a reptile cell, an avian cell, an amphibian cell, a fungal cell, an algal cell, or a fish cell.

[00293] Aspect 57. The method of aspect 54, wherein the inducible promoter is a drug-inducible promoter, and wherein the method comprises contacting the cell with a drug that induces the drug-inducible promoter.

EXAMPLES

[00294] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Celsius, and pressure is at or near atmospheric. Standard abbreviations may be used, e.g., bp, base pair(s); kb, kilobase(s); pi, picoliter(s); s or sec, second(s); min, minute(s); h or hr, hour(s); aa, amino acid(s); kb, kilobase(s); bp, base pair(s); nt, nucleotide(s); i.m., intramuscular(ly); i.p., intraperitoneal(ly); s.c., subcutaneous(ly); and the like. Example 1

[00295] To identify a Cas9 inhibitory protein, bioinformatics was used to identify bacterial strains with CRISPR arrays containing spacers that target the genome, predicted mobile genetic elements in those strains, and screened fragments of the mobile genetic elements for anti- CRISPR activity. To test for activity, a cell-free transcription-translation system, as depicted schematically in FIG. 7, was used. Essentially, a reporter pair (e.g., two fluorescent proteins, such as green fluorescent protein (GFP) and red fluorescent protein (RFP) that is transcribed and translated over time was used. A Cas9 protein and gRNAs targeting the reporters were used to cleave the reporters, thereby reducing the fluorescence levels produced by the reporters. When linear DNA or plasmid DNA encoding a test protein was included, cleavage of the reporter was reduced, and therefore the fluorescence remained high, if the test protein inhibited the Cas9.

[00296] As shown in FIG. 8, RFP reporter and candidate proteins from genomic fragment 31

(GF31) were identified as potential Cas9 inhibitors during screening of mobile genetic element DNA fragments. The candidate protein designated“GF31 cand2” was identified as a protein that exhibited anti-CRISPR activity; this candidate protein was termed AcrIIA7.

[00297] The AcrIIA7 protein was purified and tested for its ability to inhibit Staphylococcus aureus Cas9 (SauCas9) or Streptococcus pyogenes Cas9 (SpyCas9) cleavage in vitro. The results are shown in FIG. 9. AcrIIA4 is a well-characterized anti-CRISPR for SpyCas9, and which does not inhibit SauCas9, and was used as a positive control for inhibition of Spy Cas9. As shown in FIG. 9, AcrIIA7 inhibits SauCas9 activity, but does not substantially inhibit SpyCas9.

[00298] The ability of AcrIIA7 to inhibit SauCas9 in a mammalian cell was tested. A nucleic acid encoding AcrIIA7, as well as a nucleic acid encoding either blue fluorescent protein (BFP) or the fluorescent protein mCherry, were integrated into the genome of a mammalian cell line (HEK). SauCas9 targeting eGFP was delivered into the modified HEK cell lines. SauCas9 and guide RNA were provided to the cell as a preassembled ribonucleoprotein (RNP) complex. After a few days, fluorescence produced by the GFP or mCherry was measured. As shown in FIG. 10, GF31 cand2 (AcrIIA7) inhibited Cas9/guide RNA-mediated editing, while the controls did not. MATERIALS AND METHODS

[00299] The following guide RNAs (gRNA) can be used, together with Sthl Cas9, Sau Cas9,

Lga Cas9, or Spy Cas9, to target the Cas9 to enhanced GFP (eGFP).

[00300] SthlCas9 gRNA (targets eGFP in human cells) [00301] gccttcgggcatggcggacttGTTTTTGTACTCTCAAGATTCAATAATCTTGCAGAAGCT

ACAAAGATAAGGCTTCATGCCGAAATCAACACCCTGTCATTTTATGGCAGGGTGTTT TCG (SEQ ID NO:7)

[00302] SauCas9 gRNA (targets eGFP in human cells)

[00303] gcaagggcgaggagctgttcacGTTTTAGTACTCTGGAAACAGAATCTACTAAAACAAG

GCAAAATGCCGTGTTTATCTCGTCAACTTGTTGGCGAGATTTTT (SEQ ID NO: 8)

[00304] LgaCas9 gRNA (targets eGFP in human cells)

[00305] ggtcgagctggacggcgacGTTTT AGATGGTTGTT AGgaaaCT A AC A ACC AGATTT A A A A

TCAAGCAATGCATCTTTTGATGCAAAGTTTCAATACTTGTCCCGAGCTATCGAGGGA

C (SEQ ID NO:9)

[00306] SpyCas9 crRNA (targets eGFP in human cells, part of Alt-R system in IDT, pairs with tracrRNA)

[00307] ctgaagttcatctgcaccacGTTTTAGAGCTATCT (SEQ ID NO: 10)

Example 2

[00308] Inhibition of S. aureus Cas9 (“SauCas9”) by Acrs AcrIIA5 and GF31-2 (AcrIIA7) at various ratios of Acr to SauCas9 was tested. The data are shown in FIG. 11. AcrIIA5 inhibits both S. pyogenes Cas9 and S. aureus Cas9. Hynes et al. (2017) Nat. Microbiol. 2:1374. As shown in FIG. 11, GF31-2 inhibited SauCas9-mediated cleavage of target DNA at GF31- 2:SauCas9 molar ratios of 5:1, 10:1, and 20:1.

[00309] The effect of removal of the N-terminal 59 amino acids from AcrIIA7 (GF31-2) on inhibition of SauCas9 was tested. The results are shown in FIG. 12. Various ratios of truncated GF3l-2:SauCas9 were tested. As shown in FIG. 12, truncated GF31-2 inhibited SauCas9- mediated cleavage of target DNA at truncated GF3l-2:SauCas9 molar ratios of 5:1, 10:1, and 20: 1.

[00310] The truncated form of GF31-2 did not inhibit S. pyogenes Cas9 (SpyCas9). The data are shown in FIG. 13. The truncated form of GF31-2 was incubated with SpyCas9 at the indicated fold molar excess of truncated GF31-2 over SpyCas9 As shown in FIG. 13, truncated GF31-2 did not inhibit SauCas9-mediated cleavage of target DNA, even at 40-fold molar excess over SpyCas9.

Example 3

[00311] The effect of Acrs on Cas9-mediated cleavage of a target genomic nucleic acid in a mammalian cell was tested. The data are shown in FIG. 14-16.

[00312] FIG. 14 depicts the effect of anti-CRISPR protein GF3l-cand2 (gb29; a.k.a. GF31-2 or

AcrIIA7) on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus (SauCas9)/guide RNA- mediated cleavage of a genomic target nucleic acid in a mammalian cell. The data show the efficiency of Acr-mediated inhibition of genomic GFP disruption by SpyCas9 or SauCas9 with a guide RNA targeting GFP, in a human cell line. The various Cas9 and guide RNAs were expressed from separate, stably integrated lentiviral vectors. The anti-CRISPR protein was expressed from a stably integrated lentiviral vector. The reporter GFP was expressed from a stably integrated lentiviral vector under control of a doxycycline-inducible promoter. GF31- cand2 strongly inhibited SauCas9 but not SpyCas9 in mammalian cells.

[00313] FIG. 15 depicts the effect of anti-CRISPR protein GF3l-2-trunc (gb84; truncated

version of GF3l-cand2) on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus

(SauCas9)/guide RNA-mediated cleavage of a genomic target nucleic acid in a mammalian cell. The data show the efficiency of Acr-mediated inhibition of genomic GFP disruption by SpyCas9 or SauCas9 with a respective guide RNA targeting GFP, in a human cell line. The various Cas9 and guide RNAs were expressed from separate, stably integrated lentiviral vectors. The anti- CRISPR protein was expressed from a stably integrated lentiviral vector. The reporter GFP was expressed from a stably integrated lentiviral vector under control of a doxycycline-inducible promoter. GF3l-2-trunc strongly inhibited SauCas9 but not SpyCas9 in mammalian cells.

[00314] FIG. 16 depicts the effect of anti-CRISPR protein GF3l-2-hom (gb76; homologue of

GF3l-cand2) on S. pyogenes (SpyCas9)/guide RNA-mediated and S. aureus (SauCas9)/guide RNA-mediated cleavage of a genomic target nucleic acid in a mammalian cell. The data show the efficiency of Acr-mediated inhibition of genomic GFP disruption by SpyCas9 or SauCas9 with a respective guide RNA targeting GFP, in a human cell line. The various Cas9 and guide RNAs were expressed from separate, stably integrated lentiviral vectors. The anti-CRISPR protein was expressed from a stably integrated lentiviral vector. The reporter GFP was expressed from a stably integrated lentiviral vector under control of a doxycycline-inducible promoter. GF3l-2-hom inhibited SauCas9 but not SpyCas9 in mammalian cells; GF3l-2-hom inhibited SauCas9 slightly less efficiently than GF3l-cand2 and GF3l-2-trunc in mammalian cells.

[00315] While the present invention has been described with reference to the specific

embodiments thereof, it should be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process step or steps, to the objective, spirit and scope of the present invention. All such modifications are intended to be within the scope of the claims appended hereto.