Glycosylation

CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of U.S. Provisional Application No. 61/954,337, filed on March 17, 2014, the content of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Glycosylation is important to the structures and functions of glycoproteins. For example, glycosylation is suggested to affect protein folding (and thus stability) and/or bioactivities of glycoproteins. The demand of therapeutic recombinant glycoproteins, especially monoclonal antibodies, robustly grows in the recent two decades. Previous studies reveal that minor differences in glycan structures of recombinant glycoproteins may impact on the biological activities and pharmacokinetics of the glycoproteins. For example,

Darbepoetin alfa is a hyper-glycosylated analog of recombinant human erythropoietin (EPO) with two extra N-linked glycosylation sites. The extra N-glycosylation increases the percentage of the molecular mass in carbohydrates and significantly extends the serum half- life of Darbepoetin alfa, as compared to endogenous and recombinant EPO. In addition, for a therapeutic antibody whose efficacy mainly relies on antibody-dependent cell cytotoxicity (ADCC), both chemo-enzymatic and genetic approaches to remove the core fucose residue on the Fc portion have been developed to increase the potency of the ADCC effect induced by that antibody.

However, currently available methods for remodeling glycosylation often require multiple enzymes and/or multiple steps, resulting in high costs for manufacturing glyco- engineered recombinant proteins.

SUMMARY OF THE INVENTION

The present disclosure is based on the development of genetically engineered host animal cells capable of producing glycoproteins such as antibodies having modified glycosylation, including defucosylation and monoglycosylation. Such host animal cells were engineered to overly express one or more of fucosidases, endoglycosidases, or both.

Unexpectedly, changes to the cellular glycosylation machinery in the host animal cells did not result in adverse effects in relation to glycoprotein synthesis and host cell growth.

Accordingly, the present disclosure provides a genetically engineered host animal cell (e.g., a mammalian cell), which overly expresses a fucosidase, an endoglycosidase, or both, wherein the host animal cell produces glycoproteins having modified glycosylation as compared with the wild-type couterpart. In some examples, the fucosidase can be a mammalian fucosidase or a bacterial fucosidase, for example, human FUCA1, human FUCA2, Cricetulus griseus fucosidase, alpha- L-l Chryseobacterium meningosepticum ocl,6- fucosidase, or bacterial fucosidase BF3242. Alternatively or in addition, the endoglycosidase can be an Endo S enzyme, e.g., an enzyme comprising the amino acid sequence of SEQ ID NO: 11. In some examples, the genetically engineered host animal cell expresses (i) human FUCA1, human FUCA2, Cricetulus griseus fucosidase, alpha- L-l Chryseobacterium meningosepticum ccl,6-fucosidase, or bacterial fucosidase BF3242, and (ii) an Endo S (such as SEQ ID NO: 11).

The genetically engineered host animal cell described herein may further express a glycoprotein, which can be exogenous (not expressed in the native animal cell of the same type). Examples include, but are not limited to, an antibody, an Fc-fusion protein, a cytokine, a hormone, a growth factor, or an enzyme.

In some examples, the genetically engineered host animal cell is a mammalian cell, e.g., a Chinese hamster ovary (CHO) cell, a rat myeloma cell, a baby hamster kidney (BHK) cell, a hybridoma cell, a Namalwa cell, an embryonic stem cell, or a fertilized egg.

Also described herein are methods for producing glycoproteins having modified glycosylation patterns (e.g., defucosylated or mono-glycosylated) using any of the genetically engineered host animal cells described herein. The method may comprise (i) providing a host animal cell expressing (a) a glycoprotein, and (b) a fucosidase, an endoglycosidase, or both; culturing the host animal cell under conditions allowing for producing the glycoprotein and the fucosidase, the endoglycosidase, or both; (ii) collecting the host animal cell or the culturing supernatant for isolating the glycoprotein, and optionally (iii) isolating the glycoprotein. The method may further comprise (iv) analyzing the glycosylation pattern of the glycoprotein.

Further, the present disclosure features a method for preparing any of the genetically engineered host animal cells described herein. The method may comprise (i) introducing into an animal cell one or more expression vectors, which collectively encode a fucosidase, an 5 endoglycosidase, or both, and optionally (ii) introducing into the animal cell an expression vector encoding a glycoprotein. The method may further comprise selecting transformed cells expressing the fucosidase, the endoglycosidase, and the glycoprotein.

The details of one or more embodiments of the invention are set forth in the description below. Other features or advantages of the present invention will be apparent o from the following drawings and detailed description of several embodiments, and also from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic illustration showing the structures of various N-glycans. A:5 typical N-linked glycans of glycoproteins. B: defucosylated N-glycans. C: N-glycans having a mono-Nacetylglucosamine reducing sugar (monoglycosylated).

Figure 2 is a schematic illustration of an exemplary expression vector for producing a fucosidase. A: map of an exemplary plasmid that carries a fucosidase gene. B: an exemplary expression cassette for expressing a fucosidase or an endoglycosidase S.

o Figure 3 includes diagrams showing the production of homogenous afucosylated mono-sugar (GlcNAc) antibody h4B12 by transient expression of the antibody in host cells engineered to express a fucosidase and/or an endoglycosidase. A: a schematic illustration of producing homogenous afucosylated mono-sugar (GlcNAc) antibodies. B: a chart showing the glycosylation of antibody 4B12 produced in host cells engineered to express human

5 FUCA1, human FUCA2, C. griseus fucosidase, alpha-L-1, or C. meningosepticum ccl,6- fucosidase, as determined by LC/MS/MS. C: a diagram showing the transient expression of a fucosidase or an endoglycosidase as indicated in CHO cells detected by Western blot. D: a chart showing antibody h4B12 produced in CHO cells expressing a fucodisase or an endoglycosidase as indicated, the antibody having homogenous fucose-free mono-sugar 0 (GlcNAc) glycoform as determined by LC/MS/MS. A homogenous N-glycan refers to the ratio of that N-glycan (e.g. , an afucosylated N-glycan) to the total N-glycans in a

glycoprotein such as an antibody.

Figure 4 includes diagrams showing the production of homogenous afucosylated mono-sugar (GlcNAc) antibody rituximab by transient expression of the antibody in host cells engineered to express a fucosidase and/or an endoglycosidase. A: a chart showing the glycosylation of antibody rituximab produced in host cells engineered to express various fucosidases or endoglycosidases as indicated. B: a diagram showing the transient expression of a fucosidase (left lane) or an endoglycosidase (right lane) as indicated in CHO cells as detected by Westernblot.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein are genetically engineered host animal cells such as mammalian cells capable of producing glycoproteins (e.g., exogenous glycoproteins such as antibodies) having modified glycosylation patterns (e.g., modified N-glycosylation patterns such as defucosylated N-glycans or mono-sugar glycans). Such host animal cells may be engineered to overly express a fucosidase, an endoglycosidase, or both. Optionally, the host animal cell is also engineered to express an exogenous glycoprotein such as an antibody.

The structure of a typical complex N-glycan of glycoproteins produced in wild-type mammalian cells is shown in Figure 1, panel A. Such a complex N-glycan contains a N- acetylglucosamine (GlcNAc) residue attached to a glycosylation site, an asparagine residue (Asn) of a glycoprotein, and a fucose residue is attached to that Asn residue in an alphal,6- linkage. The genetically engineered host animal cells are capable of producing glycoproteins (e.g., endogenous or exogenous) having modified N-glycans, such as defucosylated N- glycans, an example of which is provided in Figure 1, panel B, and mono-sugar N-glycans, in which only a GlcNAc residue is attached to the Asn glycosylation site (Figure 1, panel C). A glycoprotein having modified glycosylation refers to a glycoprotein carrying at least one glycan such as an N-glycan that is structurally different from glycans of the glycoprotein produced in the wild-type counterpart of the genetically engineered host animal cell. A defucosylated glycan refers to any glycan that does not contain an alphal,6-fucose residue or any fucose residue.

A. Fucosidase A fucosidase is an enzyme that breaks down fucose. This enzyme cleaves fucose residues from a glycan containing such. The fucosidase for use in making the genetically engineered host animal cells can be a mammalian fucosidase or a bacterial fucosidase. In some embodiments, the fucosidase is a wild-type enzyme, e.g., a wild-type bacterial enzyme or a wild-type mammalian enzyme such as a human enzyme. The amino acid sequences and encoding nucleotide sequences of a number of exemplary fucosidases are provided below (including a His-tag at the C-terminus):

Human Fucosidase FUCA1 :

Amino Acid Sequence (SEQ ID NO: l)

MRVPAQLLGLLLLWLPGARCQPPRRYTPDWPSLDSRPLPAWFDEAKFGVFIHWGVFS VPA WGSEWFWWHWQGEGRPQYQRFMRDNYPPGFSYADFGPQFTARFFHPEEWADLFQAAGAKY VVLTTKHHEGFTNWPSPVSWNWNSKDVGPHRDLVGELGTALRKRNIRYGLYHSLLEWFHP LYLLDKKNGFKTQHFVSAKTMPELYDLVNSYKPDLIWSDGEWECPDTYWNSTNFLSWLYN DSPVKDEVVVNDRWGQNCSCHHGGYYNCEDKFKPQSLPDHKWEMCTS IDKFSWGYRRDMA LSDVTEESEI I SELVQTVSLGGNYLL IGPTKDGLIVPIFQERLLAVGKWLS INGEAIYA SKPWRVQWEKNTTSVWYTSKGSAVYAIFLHWPENGVLNLESPITTSTTKITMLGIQGDLK WSTDPDKGLFI SLPQLPPSAVPAEFAWTIKLTGVKHHHHHH

Nucleotide Sequence (SEQ ID NO:2; codon optimized) atgagagtgcctgctcagctgctgggactgctgctgctgtggctgcctggtgctagatgc cagccccctcggagatacacccctgactggccttccctggactccagacctctgcccgct tggtttgacgaggccaagttcggcgtgttcatccactggggcgtgttctccgtgcctgcc tggggctctgagtggttctggtggcattggcagggcgagggcagacctcagtaccagcgg ttcatgcgggacaactacccccctggcttctcctacgccgacttcggccctcagttcacc gcccggttcttccaccctgaggaatgggccgatctgttccaggccgctggcgccaaatac gtggtgctgaccaccaagcaccacgagggcttcaccaactggccctcccccgtgtcctgg aactggaactctaaggacgtgggcccccaccgggatctcgtgggagaactgggaaccgcc ctgcggaagcggaacatcagatacggcctgtaccactccctgctggaatggttccacccc ctgtacctgctggacaagaagaacggcttcaagacccagcacttcgtgtccgccaagacc atgcccgagctgtacgacctcgtgaactcctacaagcccgacctgatttggagcgacggc gagtgggagtgccccgacacctattggaactccaccaactttctgtcctggctgtacaac gactcccctgtgaaggacgaggtggtcgtgaacgacagatggggccagaactgctcctgt caccacggcggctactacaactgcgaggacaagttcaagccccagtccctgcccgaccac aagtgggagatgtgcacctctatcgacaagttctcctggggctaccggcgggacatggcc ctgtctgatgtgaccgaggaatccgagatcatctccgagctggtgcagaccgtgtccctg ggcggcaactacctgctgaacatcggccctaccaaggacggcctgatcgtgcccatcttc caggaacggctgctggccgtgggcaagtggctgtctatcaacggcgaggccatctacgcc tccaagccttggcgagtgcagtgggagaagaacaccacctccgtgtggtacacctccaag ggctctgccgtgtacgccatcttcctgcactggcccgagaacggcgtgctgaacctggaa tcccccatcaccacctctaccaccaagatcaccatgctgggcatccagggcgacctgaag tggtccaccgaccctgacaagggcctgttcatctccctgccccagctgcctccttccgct gtgcctgctgagttcgcctggaccatcaagctgaccggcgtgaagcaccaccaccatcac cattga

Human Fucosidase FUCA2:

Amino Acid Sequence (SEQ ID NO:3) MRVPAQLLGLLLLWLPGARCHSATRFDPTWESLDARQLPAWFDQAKFGIFIHWGVFSVPS FGSEWFWWYWQKEKIPKYVEFMKDNYPPSFKYEDFGPLFTAKFFNANQWADIFQASGAKY IVLTSKHHEGFTLWGSEYSWNWNAIDEGPKRDIVKELEVAIRNRTDLRFGLYYSLFEWFH PLFLEDESSSFHKRQFPVSKTLPELYELVNNYQPEVLWSDGDGGAPDQYWNSTGFLAWLY NESPVRGTVVTNDRWGAGS ICKHGGFYTCSDRYNPGHLLPHKWENCMTIDKLSWGYRREA GI SDYLTIEELVKQLVETVSCGGNLLMNIGPTLDGTI SVVFEERLRQMGSWLKVNGEAIY ETHTWRSQNDTVTPDVWYTSKPKEKLVYAIFLKWPTSGQLFLGHPKAILGATEVKLLGHG QPLNWI SLEQNGIMVELPQLTIHQMPCKWGWALALTNVIHHHHHH

Nucleotide Sequence (SEQ ID NO:4; codon optimized)

atgagagtgcctgctcagctgctgggactgctgctgctgtggctgcctggcgctaga tgc cactccgccaccagattcgaccccacctgggagtctctggacgccagacagctgcccgct tggtttgaccaggccaagttcggcatcttcatccactggggcgtgttctccgtgcccagc ttcggctctgagtggttctggtggtactggcagaaagagaagatccccaaatacgtggag ttcatgaaggacaactacccccccagctttaagtacgaggacttcggccccctgttcacc gccaagttcttcaacgccaaccagtgggccgacatcttccaggcctctggcgccaagtac atcgtgctgacctccaagcaccacgagggcttcaccctgtggggctccgagtactcctgg aactggaacgccatcgacgagggccccaagcgggacatcgtgaaagaactggaagtggcc atccggaaccggaccgacctgagattcggcctgtactactccctgttcgagtggttccac cccctgtttctggaagatgagtcctccagcttccacaagcggcagttccccgtgtccaag accctgcccgagctgtacgagctcgtgaacaactaccagcccgaggtgctgtggagtgac ggggatggtggtgcccccgatcagtactggaactctaccggcttcctggcctggctgtac aacgagtctcctgtgcggggcaccgtcgtgaccaacgatagatggggcgctggctccatc tgcaagcacggcggcttctacacctgttccgaccggtacaaccccggccatctgctgcct cacaagtgggagaactgcatgaccatcgacaagctgtcctggggctacagaagagaggcc ggcatctccgactacctgacaatcgaggaactcgtgaagcagctggtggaaaccgtgtcc tgcggcggcaacctgctgatgaacatcggccctaccctggacggcaccatctccgtggtg ttcgaggaacggctgcggcagatgggctcctggctgaaagtgaacggcgaggccatctac gagacacacacctggcggtcccagaacgacaccgtgacccctgacgtgtggtacaccagc aagcccaaagaaaagctggtgtatgccatcttcctgaagtggcctacctccggccagctg ttcctgggccaccctaaggctatcctgggcgccaccgaagtgaaactgctgggccatgga cagcccctgaactggatctccctggaacagaacggcatcatggtggaactgccccagctg accatccatcagatgccctgcaaatggggctgggccctggccctgaccaacgtgatccac catcaccaccaccactga Cricetulus griseus (Chinese Hamster) Fucosidase FUCA2

Amino Acid Sequence (SEQ ID NO:5) MRVPAQLLGLLLLWLPGARCKSSRRYDPTWESLDRRPLPSWFDQAKFGIFIHWGVFSVPS FGSEWFWWYWQKEKRPKFVDFMNNNYPPGFKYEDFGVLFTAKFFNASQWADILQASGAKY LVLTSKHHEGFTLWGSEYSWNWNAVDEGPKRDIVKELKVAITKNTDLRFGLYYSLFEWFH PLFLEDKLSSFQKRQFPI SKMLPELYELVNKYQPDILWTDGDGGAPDRYWNSTGFLAWLY NESPVRNTVVTNDRWGAGS ICKHGGYYTCSDRYNPGHLLPHKWENCMTIDQFSWGYRREA VI SDYLTIEELVKQLVETVACGGNLLM IGPTLDGI IPVIFEERLRQMGMWLKVNGEAIY ETQPWRSQNDTATPDVWYTYKPEEKIVYAIFLKWPVSRELFLEQPIGSLGETEVALLGEG KPLTWTSLKPNGI IVELPQLTLHQMPCKWGWTLALTNVTHHHHHH

Nucleotide Sequence (SEQ ID NO:6; codon optimized) atgagagtgcctgctcagctgctgggactgctgctgctgtggctgcctggcgctagatgc aagtcctctcggagatacgaccccacctgggagtccctggacagaaggcctctgcccagt tggttcgaccaggccaagttcggcatcttcatccactggggcgtgttctccgtgcccagc ttcggctctgagtggttctggtggtactggcagaaagagaagcggcccaagttcgtggac ttcatgaacaacaactacccccctggctttaagtacgaggacttcggcgtgctgttcacc gccaagttcttcaacgcctcccagtgggccgacatcctgcaggcttccggcgctaagtac ctggtgctgacctccaagcaccacgagggctttaccctgtggggctccgagtactcctgg aactggaacgccgtggacgagggccctaagcgggacatcgtgaaagaactgaaggtggcc atcaccaagaacaccgacctgagattcggcctgtactactccctgttcgagtggttccac cccctgtttctggaagataagctgtccagcttccagaagcggcagttccccatctccaag atgctgcccgagctgtacgagctcgtgaacaagtaccagcctgacatcctgtggaccgac ggggatggtggcgcccctgacagatactggaactctaccggcttcctggcctggctgtac aacgagtcccctgtgcggaacaccgtcgtgaccaacgacagatggggcgctggctccatc tgcaagcacggcggctactacacctgttccgaccggtacaaccccggccatctgctgcct cacaagtgggagaactgcatgacaatcgaccagttctcctggggctaccggcgcgaggcc gtgatctctgactacctgaccatcgaggaactcgtgaagcagctggtggaaaccgtggcc tgtggcggcaacctgctgatgaacatcggccctaccctggacggcatcatccccgtgatc ttcgaggaacggctgcggcagatgggcatgtggctgaaagtgaacggcgaggccatctac gagacacagccttggcggtcccagaacgacaccgccacacctgacgtgtggtacacctac aagcccgaagagaagatcgtgtacgccatcttcctgaagtggcccgtgtccagagagctg tttctggaacagcccatcggctccctgggcgagacagaagtggctctgctgggcgagggc aagcctctgacctggacctccctgaagcccaatggcatcatcgtggaactgccccagctg accctgcaccagatgccctgtaaatggggctggaccctggccctgaccaacgtgacccac caccaccatcaccactga

Chryseobacterium meningosepticum l,6-Fucosidase Amino Acid Sequence (SEQ ID NO:7) MRVPAQLLGLLLLWLPGARCHNVSEGYEKPADPLVVQNLEQWQDLKFGLFMHWGTYSQWG IVESWSLCPEDESWTQRKPEHGKSYNEYVKNYENLQTTFNPVQFNPQKWADATKKAGMKY VVFTTKHHDGFAMFDTKQSDYKITSSKTPFSKNPKADVAKEIFNTFRDNGFRIGAYFSKP DWHSDDYWWSYFPPKDRNVNYDPQKYPARWENFKKFTFNQLNEITSNYGKIDILWLDGGW VRPFHTIDP IEWQRTIKVEQDIDMDKIGTMARKNQPGI I IVDRTVPGKWENYVTPEQAV PEHALS IPWESCITMGDSFSYVPNDNYKSSQKI IETLIRI I SRGGNYLM IAPGPNGDYD AVVYERLKEI SGWMDKNQSAVFTTRALAPYHESDFYYTQSKDGKIVNVFHI SEKSNYQAP SELSFS IPENINPKTVKVLGI SSQIKWKKKGNKIHVQLPEERTKLNYSTVIQITQHHHHH H

Nucleotide Sequence (SEQ ID NO: 8; codon optimized)

atgagagtgcctgctcagctgctgggactgctgctgctgtggctgcctggcgctaga tgc cacaatgtgtccgagggctacgagaagcccgccgaccctctggtggtgcagaacctggaa cagtggcaggacctgaagttcggcctgttcatgcactggggcacctactcccagtggggc atcgtggaatcctggtccctgtgccctgaggacgagtcttggacccagcggaagcctgag cacggcaagtcctacaacgagtacgtgaagaactacgagaacctgcagaccaccttcaac cccgtgcagttcaacccccagaagtgggccgacgccaccaagaaagccggcatgaaatac gtggtgttcaccaccaagcaccacgacggcttcgccatgttcgacaccaagcagtccgac tacaagatcacctcctccaagacccccttcagcaagaaccccaaggccgacgtggccaaa gagattttcaacaccttccgggacaacggcttccggatcggcgcctacttctccaagcct gactggcactccgacgactactggtggtcctacttcccacccaaggaccggaacgtgaac tacgaccctcagaaataccccgccagatgggagaacttcaagaagttcaccttcaatcag ctgaacgagatcaccagcaactacggcaagatcgacatcctgtggctggacggcggatgg gtgcgacccttccacaccatcgaccccaacatcgagtggcagcggaccatcaaggtggaa caggacatcgacatggacaagatcggcaccatggcccggaagaaccagcccggcatcatc atcgtggaccggaccgtgcctggcaagtgggagaattacgtgacccccgagcaggccgtg cctgagcatgccctgtctatcccttgggagtcctgtatcacaatgggcgacagcttctcc tacgtgcccaacgacaactacaagtcctcccagaagatcatcgagacactgatcaggatc atctccagaggcggcaactacctgatgaatatcgcccctggccccaacggcgactacgac gctgtggtgtacgagcggctgaaagaaatctccggctggatggataagaaccagtccgcc gtgtttaccacccgggctctggccccttaccacgagtccgacttctactacacccagtcc aaggacggaaagatcgtgaacgtgttccacatctccgagaagtccaactaccaggccccc tccgagctgtccttcagcatccccgagaacatcaaccccaagaccgtgaaggtgctgggc atctccagccagatcaagtggaagaagaagggcaacaagatccacgtgcagctgcccgag gaacggaccaagctgaactactccaccgtgatccagatcacccagcaccaccaccatcac cactga

Bacterial Fucosidase BF3242

Amino Acid Sequence (SEQ ID NO:9)

MRVPAQLLGLLLLWLPGARCQQKYQPTEANLKARSEFQDNKFGIFLHWGLYAMLATG EWT MTNNNLNYKEYAKLAGGFYPSKFDADKWVAAIKASGAKYICFTTRHHEGFSMFDTKYSDY NIVKATPFKRDVVKELADACAKHGIKLHFYYSHIDWYREDAPQGRTGRRTGRPNPKGDWK SYYQFMNNQLTELLTNYGPIGAIWFDGWWDQDINPDFDWELPEQYALIHRLQPACLVGNN HHQTPFAGEDIQIFERDLPGENTAGLSGQSVSHLPLETCETMNGMWGYKITDQNYKSTKT LIHYLVKAAGKDANLLMNIGPQPDGELPEVAVQRLKEVGEWMSKYGETIYGTRGGLVAPH DWGVTTQKGNKLYVHILNLQDKALFLPIVDKKVKKAVVFADKTPVRFTKNKEGIVLELAK VPTDVDYVVELTIDHHHHHH

Nucleotide Sequence (SEQ ID NO: 10; codon optimized)

atgagagtgcctgctcagctgctgggactgctgctgctgtggctgcctggtgctaga tgc cagcagaagtaccagcccaccgaggccaacctgaaggccagatccgagttccaggacaac aagttcggcatcttcctgcactggggcctgtacgccatgctggctactggcgagtggacc atgaccaacaacaacctgaactacaaagagtacgctaagctggctggcggcttctacccc tccaagttcgacgccgacaaatgggtggccgccatcaaggcctctggcgccaagtacatc tgcttcaccacccggcaccacgagggcttctccatgttcgacaccaagtactccgactac aacatcgtgaaggccacccccttcaagcgggacgtcgtgaaagagctggccgacgcctgc gctaagcacggcatcaagctgcacttctactactcccacatcgactggtacagagaggac gccccccagggcagaaccggcagaagaacaggcagacccaaccccaagggcgactggaag tcctactaccagtttatgaacaaccagctgaccgagctgctgaccaactacggccccatc ggcgccatttggttcgacgggtggtgggaccaggacatcaaccccgacttcgactgggag ctgcccgagcagtacgccctgatccacagactgcagcccgcctgtctcgtgggcaacaac caccaccagaccccctttgccggcgaggacatccagattttcgagcgggatctgcccggc gagaacaccgctggactgtctggccagtccgtgtcccatctgcccctggaaacctgcgag acaatgaacggcatgtggggctacaagatcaccgaccagaactacaagtccaccaagaca ctgatccactacctcgtgaaagccgctggcaaggacgccaacctgctgatgaacatcggc ccccagcctgacggcgagctgcctgaagtggctgtgcagcggctgaaagaagtgggagag tggatgtctaagtacggcgagactatctacggcaccagaggcggcctggtggcccctcat gattggggcgtgaccacccagaagggcaacaagctgtacgtgcacatcctgaacctgcag gacaaggccctgttcctgcccatcgtggacaagaaagtgaagaaagccgtggtgttcgcc gacaagacccccgtgcggttcaccaagaacaaagagggcatcgtgctggaactggccaag gtgcccaccgacgtggactacgtggtggaactgaccatcgaccaccatcatcaccaccac tga

In some embodiments, the fucosidase can be an enzyme (e.g. , a wild-type enzyme) that share at least 85% (e.g. , 90%, 93%, 95%, 96%, 97%, 98%, or 99%) sequence identity as compared with any of the exemplary fucosidases provided above (e.g., SEQ ID NO: l, SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, or SEQ ID NO:9, as well as other fucosidases described herein).

The "percent identity" of two amino acid sequences is determined using the algorithm of Karlin and Altschul Proc. Natl. Acad. Sci. USA 87:2264-68, 1990, modified as in Karlin and Altschul Proc. Natl. Acad. Sci. USA 90:5873-77, 1993. Such an algorithm is incorporated into the NBLAST and XBLAST programs (version 2.0) of Altschul, et al. J.

Mol. Biol. 215:403- 10, 1990. BLAST protein searches can be performed with the XBLAST program, score=50, wordlength=3 to obtain amino acid sequences homologous to the protein molecules of the invention. Where gaps exist between two sequences, Gapped BLAST can be utilized as described in Altschul et al., Nucleic Acids Res. 25(17):3389-3402, 1997. When utilizing BLAST and Gapped BLAST programs, the default parameters of the respective programs (e.g., XBLAST and NBLAST) can be used.

Mammalian fucosidases that can be used in constructing the genetically engineered host animal cells include, but are not limited to, those disclosed under GenBank Accession Nos. NP_114409.2, XP_003811598.1, AAH03060.1, EHH53333.1, XP_001127152.1,

XP_010360962.1, XP_006084558.1, XP_004263802.1, XP_007171384.1, XP_006075254.1, XP_010982011.1 , NP_001004218.1 , and XP_010964137.1.

Bacterial fucosidases that can be used in constructing the genetically engineered host animal cells include, but are not limited to, those disclosed under GenBank Accession Nos.

WP_008769537.1, WP .032568292.1, EYA08300.1, WP_005780841.1, EXY26528.1,

WP_044654435.1, WP_029425671.1, WP_022470316.1, CDA84816.1, WP_004307183.1, and WP_008025871.1.

B. Endoglycosidase

An Endoglycosidase is an enzyme that breaks the glycosidic bonds between two sugar monomers in a glycan, thereby releasing oligosaccharides from glycoproteins or glycolipids. Endoglycosidase for use in the present disclosure (e.g. , a wild-type enzyme) includes

endoglycosidase D, endoglycosidase F, endoglycosidase Fl, endoglycosidase F2,

endoglycosidase H, and endoglycosidase S. Exemplary endoglycosidase enzymes of each subgenus are provided in the table below:

Entry Entry name Protein names Gene names Organism

Endo-beta-N-acetylglucosaminidase endOFl Elizabethkingia Fl (EC 3.2.1.96) (Di-N- meningoseptica

P36911 EBA1_ELIME acetylchitobiosyl beta-N- (Chryseobacterium acetylglucosaminidase Fl) meningosepticum) (Endoglycosidase Fl) (Mannosyl- glycoprotein endo-beta-N-acetyl- glucosaminidase Fl)

Endo-beta-N-acetylglucosaminidase endOF3 Elizabethkingia F3 (EC 3.2.1.96) (Di-N- meningoseptica acetylchitobiosyl beta-N- (Chryseobacterium

P36913 EBA3_ELIME acetylglucosaminidase F3) meningosepticum)

(Endoglycosidase F3) (Mannosyl- glycoprotein endo-beta-N-acetyl- glucosaminidase F3)

Endo-beta-N-acetylglucosaminidase endOF2 Elizabethkingia F2 (EC 3.2.1.96) (Di-N- meningoseptica acetylchitobiosyl beta-N- (Chryseobacterium

P36912 EBA2_ELIME acetylglucosaminidase F2) meningosepticum)

(Endoglycosidase F2) (Mannosyl- glycoprotein endo-beta-N-acetyl- glucosaminidase F2)

Endo-beta-N-acetylglucosaminidase Streptomyces H (EC 3.2.1.96) (DI-N- plicatus acetylchitobiosyl beta-N-

P04067 EBAG_STRPL acetylglucosaminidase H)

(Endoglycosidase H) (Endo H)

(Mannosyl-glycoprotein endo-beta- N-acetyl-glucosaminidase H)

Endoglycosidase (EndoS) (EC M837_00287 Streptococcus equi 3.2.1.96) subsp.

T0JJ04 T0JJ04_STRSZ

zooepidemicus SzS31Al

Other suitable endoglycosidase enzymes include those that share at least 85% (e.g. , 90%, 95%, 98%, or 99%) sequence identity to an of the enzymes described herein. Enzymes having a high sequence homology (e.g. , at least 85% sequence identity) with any of the above-listed endoglycosidase are expected to possess the same biological activity. Such enzymes (e.g. , wild-type enzymes) may be retrieved from a gene database such as GenBank using one of the above listed enzymes as a query.

In some embodiments, the endoglycosidase described herein is an Endo S enzyme.

Endo S is an endoglycosidase that specifically cleaves N-glycans at the first GlcNAc residues attached to the Asn glycosylation sites of Fc domains in native IgG molecules, resulting in monoglycosylated IgG molecules, i.e. , an IgG molecule having a single GlcNAc attached to an Asn glycosylation site. The amino acid sequence and the encoding nucleotide sequence are provided below: Endo S Amino Acid Sequence (SEQ ID NO: 11):

MRVPAQLLGLLLLWLPGARCAQHDSLIRVKAEDKVVQTSPSVSAIDDLHYLSENSKKEFK EGLSKAGEVPEKLKDILSKAQQADKQAKVLAEMKVPEKIAMKPLKGPLYGGYFRTWHDKT SDPAEKDKVNSMGELPKEVDLAFVFHDWTKDYSLFWQELATKHVPTLNKQGTRVIRTIPW RFLAGGDHSGIAEDTQKYPNTPEGNKALAKAIVDEYVYKYNLDGLDVDIERDS IPKVNGK ESNE IQRS IAVFEEIGKLIGPKGADKSRLFIMDSTYMADKNPLIERGAPYIDLLLVQVY GIQGEKGDWDPVARKPEKTMEERWESYSKYIRPEQYMVGFSFYEENAGSGNLWYDINERK DDHNPLNSEIAGTRAERYAKWQPKTGGVKGGIFSYAIDRDGVAHQPKKVSDDEKRTNKAI KDITDGIVKSDYKVSKALKKVMENDKSYELIDQKDFPDKALREAVIAQVGSRRGDLERFN GTLRLDNPDIKSLEGLNKLKKLAKLELIGLSQITKLDSSVLPENIKPTKDTLVSVLETYK NDDRKEEAKAIPQVALTI SGLTGLKELNLAGFDRDSLAGIDAASLTSLEKVDLSKNKLDL AAGTENRQIFDVMLSTVSNRVGSNEQTVTFDHQKPTGHYPNTYGTTSLRLPVGEGKIDLQ SQLLFGTVTNQGTLINSEADYKAYQEQLIAGRRFVDPGYAYKNFAVTYDAYKVRVTDSTL GVTDEKKLSTSKEETYKVEFFSPTNGTKPVHEAKVVVGAEKTMMVNLAAGATVIKSDSHE NAKKVFDGAIEYNPLSFSSKTS ITFEFKEPGLVKYWRFFNDITRKDDYIKEAKLEAFVGH LEDDSKVKDSLEKSTEWVTVSDYSGEAQEFSQPLD I SAKYWRVTVDTKGGRYSSPSLPE LQILGYRLPLTHDYKDDDDK Endo S Nucleotide Sequence (SEQ ID NO: 12; codon optimized)

atgagagtgcctgctcagctgctgggcctgctgctgctgtggctgcctggtgctaga tgc gcccagcacgactccctgatcagagtgaaggccgaggacaaggtggtgcagacctcccct tccgtgtccgccatcgacgacctgcactacctgtccgagaactccaagaaagagttcaaa gagggcctgtccaaggccggcgaggtgcccgaaaagctgaaggacatcctgagcaaggct cagcaggccgacaagcaggccaaggtgctggccgagatgaaggtgccagagaagatcgcc atgaagcccctgaagggccctctgtacggcggctacttcagaacctggcacgacaagacc tccgaccccgccgagaaggacaaagtgaactccatgggcgagctgcccaaagaggtggac ctggccttcgtgttccacgactggaccaaggactactccctgttctggcaggaactggcc accaagcacgtgcccaccctgaacaagcagggcaccagagtgatccggacaatcccctgg cggtttctggctggcggcgaccactctggaatcgccgaggatacccagaagtaccccaac acccccgagggcaacaaggccctggctaaggccatcgtggacgagtacgtgtacaagtac aacctggacggcctggacgtggacatcgagcgggactccatccctaaagtgaacggcaaa gagtccaacgagaacatccagcggtctatcgccgtgttcgaggaaatcggcaagctgatc ggccccaagggcgccgacaagtcccggctgttcatcatggactccacctacatggccgat aagaaccccctgatcgagagaggcgccccttacatcgatctgctgctggtgcaggtgtac ggcatccagggcgagaagggcgattgggaccctgtggcccggaagcctgaaaagaccatg gaagagagatgggagtcctactccaagtacatccggcccgagcagtatatggtgggattc agcttctacgaggaaaacgccggctccggcaacctgtggtacgacatcaacgagcggaag gacgaccacaaccctctgaactccgagatcgccggcacccgggctgagagatacgctaag tggcagcccaagaccggcggagtgaagggcggcatcttctcctacgccatcgatagggat ggcgtggcccaccagcctaagaaggtgtccgacgacgagaagcggaccaacaaggctatc aaggacatcaccgacggcatcgtgaagtccgactacaaggtgtccaaagccctgaagaaa gtgatggaaaacgacaagagctacgagctgatcgaccagaaggacttccccgataaggcc ctgcgcgaggccgtgattgctcaagtgggctccagacggggcgacctggaaagattcaac ggcaccctgcggctggacaaccccgacatcaagtccctggaaggcctgaacaaactgaag aagctggccaagctggaactgatcggactgtcccagatcacaaagctggactcctccgtg ctgcctgagaacatcaagcccaccaaggacaccctggtgtccgtgctggaaacctacaag aacgacgaccggaaagaggaagccaaggccatccctcaggtggccctgaccatctctggc ctgaccggcctgaaagagctgaatctggccggcttcgaccgggattccctggctggaatc gatgccgcctctctgacctccctggaaaaagtggacctgtctaagaacaagctggatctg gctgccggcaccgagaaccggcagatcttcgacgtgatgctgtccaccgtgtccaacaga gtgggcagcaacgagcagaccgtgaccttcgaccaccagaagcccaccggccactaccct aacacctacggcaccacctccctgagactgcctgtgggcgagggcaagatcgacctgcag tcccagctgctgttcggcaccgtgaccaaccagggcacactgatcaactccgaggccgat tacaaggcctaccaggaacagctgatcgctgggcggagattcgtggaccctggctacgct tacaagaacttcgccgtgacctacgatgcctacaaagtgcgcgtgaccgactccaccctg ggcgtgacagacgaaaagaagctgagcacctccaaagaagagacatacaaggtggaattc ttctcccccaccaatggcaccaagcctgtgcatgaggctaaggtggtcgtgggcgccgag aaaaccatgatggtcaacctggccgctggcgccaccgtgatcaagtctgactctcacgag aatgccaaaaaggtgttcgacggcgccatcgagtacaatcctctgagcttctccagcaag accagcatcaccttcgagtttaaagaacccggcctcgtgaaatactggcggttcttcaac gatatcacccgcaaggacgactacatcaaagaggctaagctggaagccttcgtgggccat ctggaagatgactccaaagtgaaggactctctggaaaagtccaccgagtgggtcaccgtg tctgactactctggcgaggcccaggaattctcccagcccctggacaacatctccgccaag tattggagagtgaccgtggacaccaagggcggacggtacagctctcctagcctgcccgag ctgcagatcctgggctacagactgcctctgacccacgactataaggacgacgacgacaaa tga

In some embodiments, an Endo S enzyme described herein can be an enzyme (e.g. , a wild-type enzyme) that share at least 85% (e.g., 90%, 93%, 95%, 96%, 97%, 98%, or 99%) sequence identity as compared with SEQ ID NO: l 1. Examples include, but are not limited to, those described under GenBank Accession Nos. EQB24254.1, WP_037584019.1, WP_012679043.1, and ADC53484.1. C. Genetically Engineered Host Animal Cells

The host animal cells described herein are genetically engineered to overly express one or more enzymes having specific glycan-modifying activities (e.g. , glycosidase or glycol- transferase). A genetically engineered host animal cell is an animal cell that carry exogenous (non-native) genetic materials, such as exogenous genes encoding one or more of the fucosidase and endoglycosidase described herein. A host cell that overly expresses an enzyme refers to a genetically engineered host cell that expresses the enzyme in a level greater (e.g., 20%, 50%, 80%, 100%, 2-fold, 5-fold, 10-fold, 50-fold, 100-fold, 1,000-fold, 10 ⁴ -fold, or 10 ⁵ -fold higher) than that of the enzyme in the wild-type counterpart of the host cell, i.e. , the same type of cell that does not contain the same genetic modification as the genetically engineered host cell. In some embodiments, a gene encoding an exogenous enzyme as described herein can be introduced into a suitable parent animal cell to produce the genetically engineered host animal cell described herein. An exogenous enzyme refers to 5 an enzyme that does not exist in the parent cell used for making the engineered host animal cell.

Genetically engineered host animal cells as described herein, which are capable of producing glycoproteins having modified glycosylation as compared with the wild-type counterpart, can be prepared by the routine recombinant technology. In some instances, a o strong promoter can be inserted upstream to an endogenous fucosidase and/or

endoglycosidase gene to enhance its expression. In other instances, exogenous genetic materials encoding one or more of fucosidases and/or endoglycosidases can be introduced into a parent host cell to produce the genetically engineered host animal cells as described herein.

5 A gene encoding a fucosidase or endoglycosidase as described herein can be inserted into a suitable expression vector (e.g., a viral vector or a non- viral vector) using methods well known in the art. Sambrook et al., Molecular Cloning, A Laboratory Mannual, 3rd Ed., Cold Spring Harbor Laboratory Press. For example, the gene and the vector can be contacted, under suitable conditions, with a restriction enzyme to create complementary ends on each o molecule that can pair with each other and be joined together with a ligase. Alternatively, synthetic nucleic acid linkers can be ligated to the termini of a gene. These synthetic linkers contain nucleic acid sequences that correspond to a particular restriction site in the vector. In some embodiments, the gene of the fucosidase or endoglycosidase is contained in an expression cassette comprising one of more of the following elements: a Kozak sequence and 5 a signal peptide sequence, which are located at the N-terminus of the enzyme, and a protein tag (e.g. , FLAG, His-tag, include chitin binding protein (CBP), maltose binding protein (MBP), and glutathione-S-transferase (GST)). The protein tag can be located at either the N- terminus or C-terminus of the enzyme. See, e.g., Figure 2, panel B.

Additionally, the expression vector can contain, for example, some or all of the

0 following: a selectable marker gene, such as the neomycin gene for selection of stable or transient transfectants in mammalian cells; enhancer/promoter sequences from the immediate early gene of human CMV for high levels of transcription; transcription termination and RNA processing signals from SV40 for mRNA stability; SV40 polyoma origins of replication and ColEl for proper episomal replication; versatile multiple cloning sites; and T7 and SP6 RNA promoters for in vitro transcription of sense and antisense RNA. Suitable vectors and methods for producing vectors containing transgenes are well known and available in the art. Sambrook et al., Molecular Cloning, A Laboratory Mannual, 3rd Ed., Cold Spring Harbor Laboratory Press.

If two or more enzymes are to be used in constructing the host animal cells described herein, for example, two or more fucosidases, two or more endoglycosidases, or a

combination of fucosidase and endoglycosidase, genes encoding the two or more enzymes can be inserted into separate express vectors or inserted into a common express vector designed for producing multiple proteins.

Expression vectors for producing the fucosidase and/or endoglycosidase may be introduced into suitable parent host cells, including, but are not limited to, murine myeloma cells (e.g., NSO cells), Chinese Hamster Ovary (CHO) cells, human embryonic kidney cells (e.g., HEK293), and human retinoblastoma cells (e.g., PER.C6) . Selection of a suitable host cell line, which is within the knowledge of those skilled in the art, would depend on the balance between the need for high productivity and the need for producing the product having desired properties.

In some instances, the expression vectors can be designed such that they can incorporate into the genome of cells by homologous or non-homologous recombination by methods known in the art. Methods for transferring expression vectors into the parent host cells include, but are not limited to, viral mediated gene transfer, liposome mediated transfer, transformation, transfection and transduction, e.g., viral mediated gene transfer such as the use of vectors based on DNA viruses such as adenovirus, adeno-associated virus and herpes virus, as well as retroviral based vectors. Examples of modes of gene transfer include e.g., naked DNA, CaP0 ₄ precipitation, DEAE dextran, electroporation, protoplast fusion, lipofection, cell microinjection, and viral vectors, adjuvant-assisted DNA, gene gun, catheters. In one example, a viral vector is used. To enhance delivery of non- viral vectors to a cell, the nucleic acid or protein can be conjugated to antibodies or binding fragments thereof which bind cell surface antigens. Liposomes that also include a targeting antibody or fragment thereof can be used in the methods described herein.

A "viral vector" as described herein refers to a recombinantly produced virus or viral 5 particle that comprises a polynucleotide to be delivered into a host cell, either in vivo, ex vivo or in vitro. Examples of viral vectors include retroviral vectors such as lentiviral vectors, adenovirus vectors, adeno-associated virus vectors and the like. In aspects where gene transfer is mediated by a retroviral vector, a vector construct refers to the polynucleotide comprising the retroviral genome or part thereof, and a therapeutic gene.

o The genetically engineered animal host cells can comprise the use of an expression cassette created for either constitutive or inducible expression of the introduced gene(s). Such an expression cassette can include regulatory elements such as a promoter, an initiation codon, a stop codon, and a polyadenylation signal. The elements can be operably linked to the gene encoding the surface protein of interest such that the gene is operational (e.g., is5 expressed) in the host cells.

A variety of promoters can be used for expression of the fucosidase and/or endoglycosidase (as well as any exogenous glycoproteins as described herein). Promoters that can be used to express the protein are well known in the art, including, but not limited to, cytomegalovirus (CMV) intermediate early promoter, a viral LTR such as the Rous sarcoma o virus LTR, HIV-LTR, HTLV-1 LTR, the simian virus 40 (SV40) early promoter, E. coli lac

UV5 promoter and the herpes simplex tk virus promoter.

Regulatable promoters can also be used. Such regulatable promoters include those using the tetracycline repressor (tetR) [Gossen, M., and Bujard, H., Proc. Natl. Acad. Sci. USA 89:5547-5551 (1992); Yao, F. et al., Human Gene Therapy, 9: 1939-1950 (1998);

5 Shockelt, P., et al., Proc. Natl. Acad. Sci. USA, 92:6522-6526 (1995)]. Other systems

include FK506 dimer, VP 16 or p65 using astradiol, RU486, diphenol murislerone or rapamycin. Inducible systems are available from Invitrogen, Clontech and Ariad.

The effectiveness of some inducible promoters can be increased over time. In such cases one can enhance the effectiveness of such systems by inserting multiple repressors in 0 tandem, e.g., TetR linked to a TetR by an internal ribosome entry site (IRES). Alternatively, one can wait at least 3 days before screening for the desired function. While some silencing may occur, it can be minimized by using a suitable number of cells, preferably at least lxlO ⁴ , more preferably at least lxlO ⁵ , still more preferably at least lxlO ⁶ , and even more preferably at least 1x10 . One can enhance expression of desired proteins by known means to enhance 5 the effectiveness of this system. For example, using the Woodchuck Hepatitis Virus

Posttranscriptional Regulatory Element (WPRE). See Loeb, V. E., et al., Human Gene Therapy 10:2295-2305 (1999); Zufferey, R., et al., J. of Virol. 73:2886-2892 (1999); Donello, J. E., et al., J. of Virol. 72:5085-5092 (1998).

Examples of polyadenylation signals useful to practice the methods described herein o include, but are not limited to, human collagen I polyadenylation signal, human collagen II polyadenylation signal, and SV40 polyadenylation signal.

The exogenous genetic material that includes fucosidase gene and/or endoglycosidase gene (as well as a glycoprotein gene as described herein) operably linked to the regulatory elements may remain present in the cell as a functioning cytoplasmic molecule, a functioning5 episomal molecule or it may integrate into the cell's chromosomal DNA. Exogenous genetic material may be introduced into cells where it remains as separate genetic material in the form of a plasmid. Alternatively, linear DNA, which can integrate into the chromosome, may be introduced into the cell. When introducing DNA into the cell, reagents, which promote DNA integration into chromosomes, may be added. DNA sequences, which are useful to o promote integration, may also be included in the DNA molecule. Alternatively, RNA may be introduced into the cell.

Selectable markers can be used to monitor uptake of the desired transgene into the host animal cells described herein. These marker genes can be under the control of any promoter or an inducible promoter. These are known in the art and include genes that change 5 the sensitivity of a cell to a stimulus such as a nutrient, an antibiotic, etc. Genes include those for neo, puro, tk, multiple drug resistance (MDR), etc. Other genes express proteins that can readily be screened for such as green fluorescent protein (GFP), blue fluorescent protein (BFP), luciferase, and LacZ. 0 D. Producing Glycoproteins Having Modified Glycosylation The genetically engineered host animal cells can be used for producing glycoproteins (e.g., endogenous or exogenous) having modified glycosylation patterns. In some

embodiments, the parent host cell for use to producing the engineered host animal cells described above already carries a gene(s) encoding an exogenous glycoprotein. In other embodiments, a gene or multiple genes encoding a glycoprotein of interest can be introduced into the genetically engineered host animal cells that express one or more fucosidase and/or endoglycosidase by methods known in the art or described herein.

Genetically engineered host animal cells capable of producing both a glycoprotein of interest and one or more of fucosidases and/or endoglycosidases can be cultured under suitable conditions allowing for expression of these proteins. The cells and/or the culture medium can be collected and the glycoprotein of interested can be isolated and purified from the cells and/or the culture medium by routine technology. The glycosylation pattern of the glycoprotein thus produced can be determined by routine technology, e.g., LC/MS/MS, to confirm modification of glycosylation.

In some examples, the glycoprotein of interest is an antibody. Exemplary antibodies include, but are not limited to, abciximab (glycoprotein Ilb/IIIa; cardiovascular disease), adalimumab (TNF-a, various auto-immune disorders, e.g., rheumatoid arthritis),

alemtuzumab (CD52; chronic lymphocytic leukemia), basiliximab (IL-2Ra receptor (CD25); transplant rejection), bevacizumab (vascular endothelial growth factor A; various cancers, e.g., colorectal cancer, non-small cell lung cancer, glioblastoma, kidney cancer; wet age- related macular degeneration), catumaxomab, cetuximab (EGF receptor, various cancers, e.g., colorectal cancer, head and neck cancer), certolizumab (e.g., certolizumab pegol) (TNF alpha; Crohn's disease, rheumatoid arthritis), Daclizumab (IL-2Ra receptor (CD25);

transplant rejection), eculizumab (complement protein C5; paroxysmal nocturnal

hemoglobinuria), efalizumab (CDl la; psoriasis), gemtuzumab (CD33; acute myelogenous leukemia (e.g., with calicheamicin)), ibritumomab tiuxetan (CD20; Non-Hodgkin lymphoma (e.g., with yttrium-90 or indium- 111)), infliximab (TNF alpha; various autoimmune disorders, e.g., rheumatoid arthritis) Muromonab-CD3 (T Cell CD3 receptor; transplant rejection), natalizumab (alpha-4 (a4) integrin; multiple sclerosis, Crohn's disease), omalizumab (IgE; allergy-related asthma), palivizumab (epitope of RSV F protein; Respiratory Syncytial Virus infection), panitumumab (EGF receptor; cancer, e.g., colorectal cancer), ranibizumab (vascular endothelial growth factor A; wet age-related macular degeneration), rituximab (CD20; Non-Hodgkin lymphoma), tositumomab (CD20; Non- Hodgkin lymphoma), trastuzumab (ErbB2; breast cancer).

In some examples, the glycoprotein of interest is a cytokine. Examples include, but are not limited to, interferons (e.g., IFN-CC, INF-β, or INF-γ), interleukins (e.g., IL-2, IL -3, IL-4, IL-5, IL-6, IL-7, IL-12), and colony stimulating factors (e.g., G-CSF, GM-CSF, M- CSF). The IFN can be, e.g., interferon alpha 2a or interferon alpha 2b. See, e.g., Mott HR and Campbell ID. "Four-helix bundle growth factors and their receptors: protein-protein interactions :" Curr Opin Struct Biol. 1995 Feb;5(l): 114-21; Chaiken IM, Williams WV.

"Identifying structure -function relationships in four-helix bundle cytokines: towards de novo mimetics design." Trends Biotechnol. 1996 Oct;14(10):369-75; Klaus W, et al., "The three- dimensional high resolution structure of human interferon alpha-2a determined by heteronuclear NMR spectroscopy in solution". J. Mol Biol., 274(4):661-75, 1997, for further discussion of certain of these cytokines.

The protein of interest may also be a cytokine protein that has a similar structure to one or more of the afore-mentioned cytokines. For example, the cytokine can be an IL-6 class cytokine such as leukemia inhibitory factor (LIF) or oncostatin M. In some

embodiments, the cytokine is one that in nature binds to a receptor that comprises a GP130 signal transducing subunit. Other four-helix bundle proteins of interest include growth hormone (GH), prolactin (PRL), and placental lactogen. In some embodiments, the target protein is an erythropoiesis stimulating agent, e.g., (EPO), which is also a four-helix bundle cytokine. In some embodiments, an erythropoiesis stimulating agent is an EPO variant, e.g., darbepoetin alfa, also termed novel erythropoiesis stimulating protein (NESP), which is engineered to contain five N-linked carbohydrate chains (two more than recombinant

HuEPO). In some embodiments, the protein comprises five helices. For example, the protein can be an interferon beta, e.g., interferon beta- la or interferon beta- lb, which (as will be appreciated) is often classified as a four-helix bundle cytokine. In some embodiments, a target protein is IL-9, IL-10, IL-11, IL-13, or IL-15. See, e.g., Hunter, CA, Nature Reviews Immunology 5, 521-531, 2005, for discussion of certain cytokines. See also Paul, WE (ed.), Fundamental Immunology, Lippincott Williams & Wilkins; 6th ed., 2008.

In addition, the protein of interest may be a protein that is approved by the US Food & Drug Administration (or an equivalent regulatory authority such as the European Medicines 5 Evaluation Agency) for use in treating a disease or disorder in humans. Such proteins may or may not be one for which a PEGylated version has been tested in clinical trials and/or has been approved for marketing. In some instances, the protein of interest is an Fc-fusion protein, including, but not limited to, abatacept, entanercept, IL-2-Fc fusion protein, CD80-Fc fusion protein, and PDLl-Fc fusion protein.

o Further, the protein of interest may be a neurotrophic factor, i.e., a factor that

promotes survival, development and/or function of neural lineage cells (which term as used herein includes neural progenitor cells, neurons, and glial cells, e.g., astrocytes,

oligodendrocytes, microglia). For example, in some embodiments, the target protein is a factor that promotes neurite outgrowth. In some embodiments, the protein is ciliary

5 neurotrophic factor (CNTF; a four-helix bundle protein) or an analog thereof such as

Axokine, which is a modified version of human Ciliary neurotrophic factor with a 15 amino acid truncation of the C terminus and two amino acid substitutions, which is three to five times more potent than CNTF in in vitro and in vivo assays and has improved stability properties.

o Alternatively, the protein of interest can be an enzyme, e.g. , an enzyme that is

important in metabolism or other physiological processes. As is known in the art, deficiencies of enzymes or other proteins can lead to a variety of disease. Such diseases include diseases associated with defects in carbohydrate metabolism, amino acid metabolism, organic acid metabolism, porphyrin metabolism, purine or pyrimidine metabolism, lysosomal 5 storage disorders, blood clotting, etc. Examples include Fabry disease, Gaucher disease,

Pompe disease, adenosine deaminase deficiency, asparaginase deficiency, porphyria, hemophilia, and hereditary angioedema. In some embodiments, a protein is a clotting or coagulation factor,(e.g., factor VII, Vila, VIII or IX). In other embodiments a protein is an enzyme that plays a role in carbohydrate metabolism, amino acid metabolism, organic acid 0 metabolism, porphyrin metabolism, purine or pyrimidine metabolism, and/or lysosomal storage, wherein exogenous administration of the enzyme at least in part alleviates the disease.

Further, the protein of interest can be a hormone, such as insulin, growth hormone, Luteinizing hormone, follicle- stimulating hormone, and thyroid- stimulating hormone. The protein of interest can also be a growth factor, including, but not limited to, adrenomedullin (AM), angiopoietin (Ang), autocrine motility factor, bone morphogenetic proteins (BMPs), brain-derived neurotrophic factor (BDNF), epidermal growth factor (EGF), erythropoietin (EPO) fibroblast growth factor (FGF), glial cell line-derived neurotrophic factor (GDNF), granulocyte colony- stimulating factor (G-CSF), granulocyte macrophage colony- stimulating factor (GM-CSF), growth differentiation factor-9 (GDF9), healing factor, hepatocyte growth factor (HGF) hepatoma-derived growth factor (HDGF), insulin-like growth factor (IGF), keratinocyte growth factor (KGF), migration- stimulating factor (MSF), myostatin (GDF-8), nerve growth factor (NGF) and other neurotrophins, platelet-derived growth factor (PDGF), thrombopoietin (TPO), transforming growth factor alpha(TGF-a), transforming growth factor beta(TGF-P), tumor necrosis factor-alpha(TNF-a), vascular endothelial growth factor (VEGF), and placental growth factor (PGF).

Without further elaboration, it is believed that one skilled in the art can, based on the above description, utilize the present invention to its fullest extent. The following specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. All publications cited herein are incorporated by reference for the purposes or subject matter referenced herein.

EXAMPLES

METHODS

i. Construction of expression vectors for producing a fucosidase or an endoglycosidase.

In order to construct expression vectors for a fucosidase or an endoglycosidase, fucosidase or endoglycosidase gene was isolated by routine technology and subjected to codon optimization based on codon usage of hamster cells. The synthetic genes were prepared by GeneArt Corp. and cloned into pcDNA3.1 B(-) Myc-His vector (Invitrogen, US) at restriction sites Bgl II/EcoR I. (Figure 2, panel A). The expression cassette of an alpha- fucosidase comprises, from 5' to 3', a Kozak sequence, an Igk leader sequence, the coding sequence of the fucosidase, and a sequence encoding a His-tag. Figure 2, panel B. The expression cassette of an endoglycosidase comprises, from 5' to 3', a Kozak sequence, an Igk leader sequence, the coding sequence of the endoglycosidase, and a sequence encoding a Flag tag. Figure 2, panel B. ii. Preparation of defucosylated antibody

An antibody producing cell line was maintained at 0.3-3.0 x 10 ⁶ viable cells/mL in a complete medium, CD FortiCHO™ medium supplemented with 8 mM L-glutamine and antidumping Agent at 1: 100 dilution (Life Technologies, USA). Cells were maintained on a shaking platform setting at 130-150rpm in an 8% C0 ₂ incubator.

To produce defucosylated antibodies, the antibody-producing cells noted above were transfected with the expression vector encoding an alpha-fucosidase described above by FreeStyleMAX reagent (Life Technologies, USA) according to manufacturer's protocol. Transfected cells were cultured in a medium comprising 4g/L of glucose and the medium was changed every other day. The cells were harvested when the cell viability was dropped below 70% ° Clarified culture supernatant was collected and purified by Protein A

Chromatography.

Hi. Analysis of glycosylation of antibodies

Recombinant antibodies prepared according to the methods described herein were reduced, alkylated, and digested overnight with trypsin in the presence of 25 mM ammonium bicarbonate buffer (pH~8) at 37 °C. PNGase F solution (3 Roche) was added to 200 of the digested sample and the mixture was incubated for another 16 hours at 37 °C. The released glycans were separated from the peptides using a Sep-Pak® CI 8 cartridge (Waters). The Sep-Pak CI 8 was washed with acetonitrile, followed by water. The PNGaseF digested sample was loaded onto the cartridge and the released glycans were eluted with 1% ethanol while the peptides remained bound to the Sep-Pak CI 8. The released protein

oligosaccharides were first purified using a porous graphite carbon column (PhyNexus) and then permethylated. All mass spectrometry experiments were performed using an Orbitrap Fusion Tribrid mass spectrometer via direct infusion into the nano-electrospray source. RESULTS

1. Production of antibodies h4B12, rituximab, and omalizumab having mono-sugar (GlcNAc) glycoform A monosaccharide glycovariant could be made from the aforementioned di-sugar variant by a fucosidase cleavage reaction. Search from a number of available enzymes and glycol-peptide analysis by LC/MS/MS indicated that, with optimized cleavage reaction conditions, an efficient de-fucosidation could be achieved using an cc-l,6-fucosidase, and that a higher cleavage efficiency is associated with a lower NF/N ratio. Alternatively, a mono-sugar glycovariant could be obtained with two reaction enzymes combined in sequence, including an endoglycosisase (Endo S) and an cc-l,6-fucosidase. The resultant mono-GlcNAc glycovariant was shown in Figure 3, panel A.

The results show that Endo-S removed >90% N-linked glycans of the heavy chain of h4B12, rituximab, and omalizumab produced in the engineered CHO cells described herein. The defucosylation ability of five different types of fucosidases: FUCAl, FUCA2, Cricetulus griseus fucosidase, alpha-L-1, Chryseobacterium meningosepticum al,6-Fucosidas, and BF3242 are 5.8%, 9.1%, 17.7%, 11.5 and 68%, respectively, in relation to h4B12 antibodies produced in the CHO cells expressing each of the fucosidase. Figure 3, panel B. The expression of the enzymes was detect by Western blot as shown in Figure 3, panel C.

2-deoxy-2-fluoro L-Fucose is a fluorinated fucose analog. It can be metabolized inside host cells to generate a substrate-based inhibitor of fucosyltransferases. When culturing antibody-producing CHO cells transiently expressing fucosidase BF3242 and Endo- S, 99.89% of the N-glycans linked to the antibody produced in the CHO cells are

monoglycosylated (GlcNAc-Ig-Fc). Figure 3, panel D.

CHO-35D6 cells, which produce rituximab, were stable transfected with an expression vector for producing BF3242 and Endo-S. The cells were cultured in the presence of 100-400 μ^πύ G418. The antibody thus produced contains 17-19% of GlcNAc-Ig-Fc. Figure 4, panel A.

Enzyme expression was detect by Western blot as shown in Figure 4, panel B.

Similar results were observed in omalizumab produced in CHO cells engineered to express both a fucosidase and Endo S. Such efficiency represents an important step for transglycosylation in the preparation of antibodies with homogeneous glycan form.

OTHER EMBODIMENTS

All of the features disclosed in this specification may be combined in any

combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the claims.