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Jaramillo ML, Sulea T, Durocher Y, Acchione M, Schur MJ, Robotham A, Kelly JF, Goneau MF, Robert A, Cepero-Donates Y, Gilbert M. A glyco-engineering approach for site-specific conjugation to Fab glycans. MAbs 2023; 15:2149057. [PMID: 36447399 PMCID: PMC9715014 DOI: 10.1080/19420862.2022.2149057] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Effective processes for synthesizing antibody-drug conjugates (ADCs) require: 1) site-specific incorporation of the payload to avoid interference with binding to the target epitope, 2) optimal drug/antibody ratio to achieve sufficient potency while avoiding aggregation or solubility problems, and 3) a homogeneous product to facilitate approval by regulatory agencies. In conventional ADCs, the drug molecules are chemically attached randomly to antibody surface residues (typically Lys or Cys), which can interfere with epitope binding and targeting, and lead to overall product heterogeneity, long-term colloidal instability and unfavorable pharmacokinetics. Here, we present a more controlled process for generating ADCs where drug is specifically conjugated to only Fab N-linked glycans in a narrow ratio range through functionalized sialic acids. Using a bacterial sialytransferase, we incorporated N-azidoacetylneuraminic acid (Neu5NAz) into the Fab glycan of cetuximab. Since only about 20% of human IgG1 have a Fab glycan, we extended the application of this approach by using molecular modeling to introduce N-glycosylation sites in the Fab constant region of other therapeutic monoclonal antibodies. We used trastuzumab as a model for the incorporation of Neu5NAz in the novel Fab glycans that we designed. ADCs were generated by clicking the incorporated Neu5NAz with monomethyl auristatin E (MMAE) attached to a self-immolative linker terminated with dibenzocyclooctyne (DBCO). Through this process, we obtained cetuximab-MMAE and trastuzumab-MMAE with drug/antibody ratios in the range of 1.3 to 2.5. We confirmed that these ADCs still bind their targets efficiently and are as potent in cytotoxicity assays as control ADCs obtained by standard conjugation protocols. The site-directed conjugation to Fab glycans has the additional benefit of avoiding potential interference with effector functions that depend on Fc glycan structure.
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Affiliation(s)
- Maria L. Jaramillo
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Traian Sulea
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Yves Durocher
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Mauro Acchione
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Melissa J. Schur
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6, Ottawa, ON, Canada
| | - Anna Robotham
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6, Ottawa, ON, Canada
| | - John F. Kelly
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6, Ottawa, ON, Canada
| | - Marie-France Goneau
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6, Ottawa, ON, Canada
| | - Alma Robert
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Yuneivy Cepero-Donates
- Human Health Therapeutics Research Centre, National Research Council Canada, 6100 Royalmount Avenue, H4P 2R2, Montreal, Qc, Canada
| | - Michel Gilbert
- Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6, Ottawa, ON, Canada,CONTACT Michel Gilbert Human Health Therapeutics Research Centre, National Research Council Canada, 100 Sussex Drive, K1A 0R6Ottawa, ON, Canada
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Gulati S, Schoenhofen IC, Lindhout-Djukic T, Schur MJ, Landig CS, Saha S, Deng L, Lewis LA, Zheng B, Varki A, Ram S. Therapeutic CMP-Nonulosonates against Multidrug-Resistant Neisseria gonorrhoeae. J Immunol 2020; 204:3283-3295. [PMID: 32434942 DOI: 10.4049/jimmunol.1901398] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 04/08/2020] [Indexed: 12/29/2022]
Abstract
Neisseria gonorrhoeae deploys a unique immune evasion strategy wherein the lacto-N-neotetraose termini of lipooligosaccharide (LOS) are "capped" by a surface LOS sialyltransferase (Lst), using extracellular host-derived CMP-sialic acid (CMP-Neu5Ac in humans). LOS sialylation enhances complement resistance by recruiting factor H (FH; alternative complement pathway inhibitor) and also by limiting classical pathway activation. Sialylated LOS also engages inhibitory Siglecs on host leukocytes, dampening innate immunity. Previously, we showed that analogues of CMP-sialic acids (CMP-nonulosonates [CMP-NulOs]), such as CMP-Leg5,7Ac2 and CMP-Neu5Ac9N3, are also substrates for Lst. Incorporation of Leg5,7Ac2 and Neu5Ac9N3 into LOS results in N. gonorrhoeae being fully serum sensitive. Importantly, intravaginal administration of CMP-Leg5,7Ac2 attenuated N. gonorrhoeae colonization of mouse vaginas. In this study, we characterize and develop additional candidate therapeutic CMP-NulOs. CMP-ketodeoxynonulosonate (CMP-Kdn) and CMP-Kdn7N3, but not CMP-Neu4,5Ac2, were substrates for Lst, further elucidating gonococcal Lst specificity. Lacto-N-neotetraose LOS capped with Kdn and Kdn7N3 bound FH to levels ∼60% of that seen with Neu5Ac and enabled gonococci to resist low (3.3%) but not higher (10%) concentrations of human complement. CMP-Kdn, CMP-Neu5Ac9N3, and CMP-Leg5,7Ac2 administered intravaginally (10 μg/d) to N. gonorrhoeae-colonized mice were equally efficacious. Of the three CMP-NulOs above, CMP-Leg5,7Ac2 was the most pH and temperature stable. In addition, Leg5,7Ac2-fed human cells did not display this NulO on their surface. Moreover, CMP-Leg5,7Ac2 was efficacious against several multidrug-resistant gonococci in mice with a humanized sialome (Cmah-/- mice) or humanized complement system (FH/C4b-binding protein transgenic mice). CMP-Leg5,7Ac2 and CMP-Kdn remain viable leads as topical preventive/therapeutic agents against the global threat of multidrug-resistant N. gonorrhoeae.
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Affiliation(s)
- Sunita Gulati
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Ian C Schoenhofen
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada;
| | - Theresa Lindhout-Djukic
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Melissa J Schur
- Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Corinna S Landig
- Department of Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093; and.,Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093
| | - Sudeshna Saha
- Department of Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093; and.,Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093
| | - Lingquan Deng
- Department of Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093; and.,Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093
| | - Lisa A Lewis
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Bo Zheng
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Ajit Varki
- Department of Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093; and.,Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093
| | - Sanjay Ram
- Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, MA 01605;
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Aubry A, Zou W, Vinogradov E, Williams D, Chen W, Harris G, Zhou H, Schur MJ, Gilbert M, Douce GR, Logan SM. In vitro Production and Immunogenicity of a Clostridium Difficile Spore-Specific BclA3 Glycopeptide Conjugate Vaccine. Vaccines (Basel) 2020; 8:vaccines8010073. [PMID: 32046000 PMCID: PMC7157674 DOI: 10.3390/vaccines8010073] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Revised: 02/04/2020] [Accepted: 02/04/2020] [Indexed: 02/06/2023] Open
Abstract
Abstract: The BclA3 glycoprotein is a major component of the exosporangial layer of Clostridium difficile spores and in this study we demonstrate that this glycoprotein is a major spore surface associated antigen. Here, we confirm the role of SgtA glycosyltransferase (SgtA GT) in BclA3 glycosylation and recapitulate this process by expressing and purifying SgtA GT fused to MalE, the maltose binding protein from Escherichia coli. In vitro assays using the recombinant enzyme and BclA3 synthetic peptides demonstrated that SgtA GT was responsible for the addition of β-O-linked GlcNAc to threonine residues of each synthetic peptide. These peptide sequences were selected from the central, collagen repeat region of the BclA3 protein. Following optimization of SgtA GT activity, we generated sufficient glycopeptide (10 mg) to allow conjugation to KLH (keyhole limpet hemocyanin) protein. Glycosylated and unglycosylated versions of these conjugates were then used as antigens to immunize rabbits and mice. Immune responses to each of the conjugates were examined by Enzyme Linked Immunosorbent Assay ELISA. Additionally, the BclA3 conjugated peptide and glycopeptide were used as antigens in an ELISA assay with serum raised against formalin-killed spores. Only the glycopeptide was recognized by anti-spore polyclonal immune serum demonstrating that the glycan moiety is a predominant spore-associated surface antigen. To determine whether antibodies to these peptides could modify persistence of spores within the gut, animals immunized intranasally with either the KLH-glycopeptide or KLH-peptide conjugate in the presence of cholera toxin, were challenged with R20291 spores. Although specific antibodies were raised to both antigens, immunization did not provide any protection against acute or recurrent disease.
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Affiliation(s)
- Annie Aubry
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Wei Zou
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Evguenii Vinogradov
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Dean Williams
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Wangxue Chen
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Greg Harris
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Hongyan Zhou
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Melissa J. Schur
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Michel Gilbert
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
| | - Gillian R. Douce
- Institute of Infection, Immunity, Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TA, Scotland, UK;
| | - Susan M. Logan
- Vaccine Program, Human Health Therapeutics Research Centre, National Research Council of Canada, Ottawa, ON K1A 0R6, Canada; (A.A.); (W.Z.); (E.V.); (D.W.); (W.C.); (G.H.); (H.Z.); (M.J.S.); (M.G.)
- Correspondence: ; Tel.: +613-990-0839
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Haji-Ghassemi O, Gilbert M, Spence J, Schur MJ, Parker MJ, Jenkins ML, Burke JE, van Faassen H, Young NM, Evans SV. Molecular Basis for Recognition of the Cancer Glycobiomarker, LacdiNAc (GalNAc[β1→4]GlcNAc), by Wisteria floribunda Agglutinin. J Biol Chem 2016; 291:24085-24095. [PMID: 27601469 DOI: 10.1074/jbc.m116.750463] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Indexed: 01/10/2023] Open
Abstract
Aberrant glycosylation and the overexpression of specific carbohydrate epitopes is a hallmark of many cancers, and tumor-associated oligosaccharides are actively investigated as targets for immunotherapy and diagnostics. Wisteria floribunda agglutinin (WFA) is a legume lectin that recognizes terminal N-acetylgalactosaminides with high affinity. WFA preferentially binds the disaccharide LacdiNAc (β-d-GalNAc-[1→4]-d-GlcNAc), which is associated with tumor malignancy in leukemia, prostate, pancreatic, ovarian, and liver cancers and has shown promise in cancer glycobiomarker detection. The mechanism of specificity for WFA recognition of LacdiNAc is not fully understood. To address this problem, we have determined affinities and structure of WFA in complex with GalNAc and LacdiNAc. Affinities toward Gal, GalNAc, and LacdiNAc were measured via surface plasmon resonance, yielding KD values of 4.67 × 10-4 m, 9.24 × 10-5 m, and 5.45 × 10-6 m, respectively. Structures of WFA in complex with LacdiNAc and GalNAc have been determined to 1.80-2.32 Å resolution. These high resolution structures revealed a hydrophobic groove complementary to the GalNAc and, to a minor extent, to the back-face of the GlcNAc sugar ring. Remarkably, the contribution of this small hydrophobic surface significantly increases the observed affinity for LacdiNAc over GalNAc. Tandem MS sequencing confirmed the presence of two isolectin forms in commercially available WFA differing only in the identities of two amino acids. Finally, the WFA carbohydrate binding site is similar to a homologous lectin isolated from Vatairea macrocarpa in complex with GalNAc, which, unlike WFA, binds not only αGalNAc but also terminal Ser/Thr O-linked αGalNAc (Tn antigen).
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Affiliation(s)
- Omid Haji-Ghassemi
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Michel Gilbert
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Jenifer Spence
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Melissa J Schur
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Matthew J Parker
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Meredith L Jenkins
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - John E Burke
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Henk van Faassen
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - N Martin Young
- Human Health Therapeutics, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Stephen V Evans
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
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Watson DC, Wakarchuk WW, Leclerc S, Schur MJ, Schoenhofen IC, Young NM, Gilbert M. Sialyltransferases with enhanced legionaminic acid transferase activity for the preparation of analogs of sialoglycoconjugates. Glycobiology 2015; 25:767-73. [DOI: 10.1093/glycob/cwv017] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/10/2015] [Indexed: 11/15/2022] Open
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Schur MJ, Lameignere E, Strynadka NCJ, Wakarchuk WW. Characterization of α2,3- and α2,6-sialyltransferases from Helicobacter acinonychis. Glycobiology 2012; 22:997-1006. [PMID: 22504533 DOI: 10.1093/glycob/cws071] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Genome sequence data were used to clone and express two sialyltransferase enzymes of the GT-42 family from Helicobacter acinonychis ATCC 51104, a gastric disease isolate from Cheetahs. The deposited genome sequence for these genes contains a large number of tandem repeat sequences in each of them: HAC1267 (RQKELE)(15) and HAC1268 (EEKLLEFKNI)(13). We obtained two clones with different numbers of repeat sequences for the HAC1267 gene homolog and a single clone for the HAC1268 gene homolog. Both genes could be expressed in Escherichia coli and sialyltransferase activity was measured using synthetic acceptor substrates containing a variety of terminal sugars. Both enzymes were shown to have a preference for N-acetyllactosamine, and they each made a product with a different linkage to the terminal galactose. HAC1267 is a mono-functional α2,3-sialyltransferase, whereas HAC1268 is a mono-functional α2,6-sialyltransferase and is the first member of GT-42 to show α2,6-sialyltransferase activity.
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Affiliation(s)
- Melissa J Schur
- National Research Council Canada, Institute for Biological Sciences, Ottawa, ON, Canada
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Tateno H, Li H, Schur MJ, Bovin N, Crocker PR, Wakarchuk WW, Paulson JC. Distinct endocytic mechanisms of CD22 (Siglec-2) and Siglec-F reflect roles in cell signaling and innate immunity. Mol Cell Biol 2007; 27:5699-710. [PMID: 17562860 PMCID: PMC1952126 DOI: 10.1128/mcb.00383-07] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sialic acid-binding immunoglobulin-like lectins (siglecs) are predominately expressed on immune cells. They are best known as regulators of cell signaling mediated by cytoplasmic tyrosine motifs and are increasingly recognized as receptors for pathogens that bear sialic acid-containing glycans. Most siglec proteins undergo endocytosis, an activity tied to their roles in cell signaling and innate immunity. Here, we investigate the endocytic pathways of two siglec proteins, CD22 (Siglec-2), a regulator of B-cell signaling, and mouse eosinophil Siglec-F, a member of the rapidly evolving CD33-related siglec subfamily that are expressed on cells of the innate immune system. CD22 exhibits hallmarks of clathrin-mediated endocytosis and traffics to recycling compartments, consistent with previous reports demonstrating its localization to clathrin domains. Like CD22, Siglec-F mediates endocytosis of anti-Siglec-F and sialoside ligands, a function requiring intact tyrosine-based motifs. In contrast, however, we find that Siglec-F endocytosis is clathrin and dynamin independent, requires ADP ribosylation factor 6, and traffics to lysosomes. The results suggest that these two siglec proteins have evolved distinct endocytic mechanisms consistent with roles in cell signaling and innate immunity.
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Affiliation(s)
- Hiroaki Tateno
- Department of Molecular Biology and Molecular and Experimental Medicine, The Scripps Research Institute, San Diego, CA, USA
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Logan SM, Altman E, Mykytczuk O, Brisson JR, Chandan V, Schur MJ, St Michael F, Masson A, Leclerc S, Hiratsuka K, Smirnova N, Li J, Wu Y, Wakarchuk WW. Novel biosynthetic functions of lipopolysaccharide rfaJ homologs from Helicobacter pylori. Glycobiology 2005; 15:721-33. [PMID: 15814825 DOI: 10.1093/glycob/cwi057] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Activity screening and insertional inactivation of lipopolysaccharide (LPS) biosynthetic genes in Helicobacter pylori have led to the successful characterization of two key enzymes encoded by HP0159 (JHP0147) and HP1105 (JHP1032) open reading frames (ORFs) which are members of the large and diverse carbohydrate active enzymes (CAZY) GT-8 (rfaJ) family of glycosyltransferases. Activity screening of a genomic library led to the identification of the enzyme involved in the biosynthesis of the type 2 N-acetyl-lactosamine O-chain backbone, the beta-1,3-N-acetyl-glucosaminyl transferase. In addition, the activity screening approach led to the identification and characterization of a key core biosynthetic enzyme responsible for the biosynthesis of the alpha-1,6-glucan polymer. This alpha-1,6-glucosyltransferase protein is encoded by the HP0159 ORF. Both enzymes play an integral part in the biosynthesis of LPS, and insertional inactivation leads to the production of a truncated LPS molecule on the bacterial cell surface. The LPS structures were determined by mass spectrometry and chemical analyses. The linkage specificity of each glycosyltransferase was determined by nuclear magnetic resonance (NMR) analysis of model compounds synthesized in vitro. A cryogenic probe was used to structurally characterize nanomole amounts of the product of the HP1105 (JHP1032) enzyme. In contrast to the HP0159 enzyme, which displays the GT-8-predicted retaining stereochemistry for the reaction product, HP1105 (JHP1032) is the first member of this GT-8 family to have been shown to have an inverting stereochemistry in its reaction products.
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Affiliation(s)
- Susan M Logan
- Institute for Biological Sciences, National Research Council, Ottawa, Ontario, Canada K1A OR6.
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Wakarchuk W, Schur MJ, St Michael F, Li J, Eichler E, Whitfield D. Characterization of the -1,2-N-acetylglucosaminyltransferase of Neisseria gonorrhoeae, a key control point in lipooligosaccharride biosynthesis. Glycobiology 2004; 14:537-46. [PMID: 15044393 DOI: 10.1093/glycob/cwh074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The biosynthesis of the lipooligosaccharide (LOS) in Neisseria meningitidis has a control point that regulates the extension of the alpha-chain on heptose (I) of the LOS. The gene that encodes the protein responsible for this control had been identified elsewhere, but the enzyme encoded by the gene was not characterized. We have now shown that this same control mechanism operates in the related species, Neisseria gonorrhoeae, using a gene knockout and subsequent characterization of the LOS species produced. We also cloned and expressed the enzyme from both of these pathogens. Using a synthetic acceptor substrate, we have shown unequivocally that the enzyme is an alpha-1,2-N-acetylglucosaminyltransferase. Experiments with both the core oligosaccharide and the synthetic acceptors suggests that the addition of the alpha-1,2-N-acetylglucosamine moiety on the heptose (II) residue precedes the addition of the ethanolamine phosphate at the O3 position on this heptose (II), and that in the absence of the alpha-1,2-N-acetylglucosamine moiety leads to the addition of an extra ethanolamine phosphate on the heptose (II) residue. Our data do not support the hypothesis that ethanolamine phosphate at O3 of heptose (II) is added and is then required for the addition of the N-acetylglucosamine at O2 by the LgtK enzyme. This enzyme represents a control point in the biosynthesis of the LOS of this pathogen and is a potential target for therapeutic intervention.
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Affiliation(s)
- Warren Wakarchuk
- National Research Council of Canada, Institute for Biological Sciences, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6 Canada.
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Yan F, Mehta S, Eichler E, Wakarchuk WW, Gilbert M, Schur MJ, Whitfield DM. Simplifying oligosaccharide synthesis: efficient synthesis of lactosamine and siaylated lactosamine oligosaccharide donors. J Org Chem 2003; 68:2426-31. [PMID: 12636412 DOI: 10.1021/jo026569v] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A practical sequence is described for converting d-glucosamine into peracetylated Gal(beta-1,4)GlcNTroc(beta1-S)Ph and Neu5Ac(alpha-2,3)Gal(beta-1,4)GlcNTroc(beta1-S)Ph building blocks using a synthetic strategy based on chemoenzymatic oligosaccharide synthesis. The known trichloroethoxycarbonyl, N-Troc, protecting group was selected as a suitable protecting group for both enzymatic and chemical reaction conditions. These oligosaccharide building blocks proved effective donors for the beta-selective glycosylation of the unreactive OH-3 of a polymeric PEG-bound acceptor and for the axial OH-2 of a mannose acceptor in good yields. The resulting complex oligosaccharides are useful for vaccine and pharmaceutical applications.
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Affiliation(s)
- Fengyang Yan
- Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Room 3024, Ottawa, Ontario, K1A 0R6, Canada
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Blixt O, Brown J, Schur MJ, Wakarchuk W, Paulson JC. Efficient preparation of natural and synthetic galactosides with a recombinant beta-1,4-galactosyltransferase-/UDP-4'-gal epimerase fusion protein. J Org Chem 2001; 66:2442-8. [PMID: 11281786 DOI: 10.1021/jo0057809] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The numerous biological roles of LacNAc-based oligosaccharides have led to an increased demand for these structures for biological studies. In this report, an efficient route for the synthesis of beta-galactosides using a bacterial beta-4-galactosyltransferase/-UDP-4'-gal-epimerase fusion protein is described. The lgtB gene from Neisseria meningitidis and the galE gene from Streptococcus thermophilus were fused and cloned into an expression vector pCW. The fusion protein transfers galactose to a variety of different glucose- and glucosamine-containing acceptors, and utilizes either UDP-galactose or UDP-glucose as donor substrates. A crude lysate from Escherichia coli expressing the fusion protein is demonstrated to be sufficient for the efficient preparation of galactosylated oligosaccharides from inexpensive UDP-glucose in a multigram scale. Lysates containing the fusion protein are also found to be useful in the production of more complex oligosaccharides in coupled reaction mixtures, e.g., in the preparation of sialosides from N-acetylglucosamine. Thus, bacterially expressed fusion protein is well suited for the facile and economic preparation of natural oligosaccharides and synthetic derivatives based on the lactosamine core.
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Affiliation(s)
- O Blixt
- Department of Molecular Biology, The Scripps Research Institute, MEM-L71, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Creuzenet C, Schur MJ, Li J, Wakarchuk WW, Lam JS. FlaA1, a new bifunctional UDP-GlcNAc C6 Dehydratase/ C4 reductase from Helicobacter pylori. J Biol Chem 2000; 275:34873-80. [PMID: 10954725 DOI: 10.1074/jbc.m006369200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
FlaA1 is a small soluble protein of unknown function in Helicobacter pylori. It has homologues that are essential for the virulence of numerous medically relevant bacteria. FlaA1 was overexpressed as a histidine-tagged protein and purified to homogeneity by nickel chelation and cation exchange chromatography. Spectrophotometric assays, capillary electrophoresis, and mass spectrometry analyses showed that FlaA1 is a novel bifunctional C(6) dehydratase/C(4) reductase specific for UDP-GlcNAc. It converts UDP-GlcNAc into a UDP-4-keto-6-methyl-GlcNAc intermediate, which is stereospecifically reduced into UDP-QuiNAc. Substrate conversions as high as 80% were obtained at equilibrium. The K(m) and V(max) for UDP-GlcNAc were 159 microm and 65 pmol/min, respectively. No exogenous cofactor was required to obtain full activity of FlaA1. Additional NADH was only used with poor efficiency for the reduction step. The biochemical characterization of FlaA1 is important for the elucidation of biosynthetic pathways that lead to the formation of 2,6-deoxysugars in medically relevant bacteria. It establishes unambiguously the first step of the pathway and provides the means of preparing the substrate UDP-QuiNAc, which is necessary for the study of downstream enzymes.
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Affiliation(s)
- C Creuzenet
- University of Guelph, Department of Microbiology, Guelph, Ontario N1G 2W1, Canada
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Latta RK, Schur MJ, Tolson DL, Altman E. The effect of growth conditions on in vitro adherence, invasion, and NAF expression by Proteus mirabilis 7570. Can J Microbiol 1998; 44:896-904. [PMID: 9851028 DOI: 10.1139/cjm-44-9-896] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteus mirabilis is a common cause of upper urinary tract infections. Fimbriae-mediated adherence of this organism to urinary tract epithelium and invasion of host cells are factors thought to be important in its pathogenesis. We have assessed the effect of growth in serum, blood, and urine on the ability of P. mirabilis 7570 to adhere to and invade in vitro the cell line EJ/28, derived from a human urinary tract tumour, and to express nonagglutinating fimbriae (NAF). Proteus mirabilis was capable of adhering to EJ/28 cells to varying degrees depending upon the growth conditions used. It was invasive under all conditions, except when grown in urine, and was found to be particularly so when serum or blood was present in the media. Expression of NAF occurred under all growth conditions examined and was limited only by a decrease in temperature.
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Affiliation(s)
- R K Latta
- Institute for Biological Sciences, National Research Council Canada, Ottawa.
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Latta RK, Schur MJ, Tolson DL, Altman E. The effect of growth conditions on in vitro adherence, invasion, and NAF expression by Proteus mirabilis 7570. Can J Microbiol 1998. [DOI: 10.1139/w98-082] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteus mirabilis is a common cause of upper urinary tract infections. Fimbriae-mediated adherence of this organism to urinary tract epithelium and invasion of host cells are factors thought to be important in its pathogenesis. We have assessed the effect of growth in serum, blood, and urine on the ability of P. mirabilis 7570 to adhere to and invade in vitro the cell line EJ/28, derived from a human urinary tract tumour, and to express nonagglutinating fimbriae (NAF). Proteus mirabilis was capable of adhering to EJ/28 cells to varying degrees depending upon the growth conditions used. It was invasive under all conditions, except when grown in urine, and was found to be particularly so when serum or blood was present in the media. Expression of NAF occurred under all growth conditions examined and was limited only by a decrease in temperature.Key words: adhesion, invasion, nonagglutinating fimbriae, Proteus mirabilis.
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