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Rao D, Zhu L, Liu W, Guo Z. Molecular Mechanism of Double-Displacement Retaining β-Kdo Glycosyltransferase WbbB. J Phys Chem B 2024. [PMID: 39051443 DOI: 10.1021/acs.jpcb.4c02073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Glycosyltransferases (GTs) are pivotal enzymes involved in glycosidic bond synthesis, which can lead to either retention or inversion of the glycosyl moiety's anomeric configuration. However, the catalytic mechanism for retaining GTs remains a subject of controversy. In this study, we employ MD and QM/MM metadynamics to investigate the double-displacement catalytic mechanism of the retaining β-Kdo transferase WbbB. Our findings demonstrate that the nucleophile Asp232 initiates the reaction by attacking the sugar ring containing a carboxylate at the anomeric position, forming a covalent adduct. Subsequently, the adduct undergoes a rotational rearrangement, ensuring proper orientation of the anomeric carbon for the acceptor substrate. In the second step, Glu158 acts as the catalytic base to abstract the proton of the acceptor substrate to complete the transglycosylation reaction. Notably, His265 does not function as the anticipated catalytic acid; instead, it stabilizes the phosphate group through H-bonding interactions. Our simulations support the double-displacement mechanism implicated from the crystallographic studies of WbbB. This mechanism deviates from the common SNi-type and retaining glycoside hydrolase mechanisms, thereby expanding our understanding of GT catalytic mechanisms.
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Affiliation(s)
- Deming Rao
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Lin Zhu
- School of Life Science and Technology, Wuhan Polytechnic University, Wuhan 430023, People's Republic of China
| | - Weiqiong Liu
- State Key Laboratory of Food Science and Resources, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, People's Republic of China
- School of Biotechnology and Key Laboratory of Industrial Biotechnology Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, People's Republic of China
- International Joint Laboratory on Food Safety, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, People's Republic of China
| | - Zhiyong Guo
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Key Laboratory of Industrial Biotechnology, School of Life Sciences, Hubei University, Wuhan 430062, People's Republic of China
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2
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Abstract
The ability to site-selectively modify equivalent functional groups in a molecule has the potential to streamline syntheses and increase product yields by lowering step counts. Enzymes catalyze site-selective transformations throughout primary and secondary metabolism, but leveraging this capability for non-native substrates and reactions requires a detailed understanding of the potential and limitations of enzyme catalysis and how these bounds can be extended by protein engineering. In this review, we discuss representative examples of site-selective enzyme catalysis involving functional group manipulation and C-H bond functionalization. We include illustrative examples of native catalysis, but our focus is on cases involving non-native substrates and reactions often using engineered enzymes. We then discuss the use of these enzymes for chemoenzymatic transformations and target-oriented synthesis and conclude with a survey of tools and techniques that could expand the scope of non-native site-selective enzyme catalysis.
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Affiliation(s)
- Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Harrison M Snodgrass
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Christian A Gomez
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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3
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Konvalinková D, Dolníček F, Hovorková M, Červený J, Kundrát O, Pelantová H, Petrásková L, Cvačka J, Faizulina M, Varghese B, Kovaříček P, Křen V, Lhoták P, Bojarová P. Glycocalix[4]arenes and their affinity to a library of galectins: the linker matters. Org Biomol Chem 2023; 21:1294-1302. [PMID: 36647793 DOI: 10.1039/d2ob02235d] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Galectins are lectins that bind β-galactosides. They are involved in important extra- and intracellular biological processes such as apoptosis, and regulation of the immune system or the cell cycle. High-affinity ligands of galectins may introduce new therapeutic approaches or become new tools for biomedical research. One way of increasing the low affinity of β-galactoside ligands to galectins is their multivalent presentation, e.g., using calixarenes. We report on the synthesis of glycocalix[4]arenes in cone, partial cone, 1,2-alternate, and 1,3-alternate conformations carrying a lactosyl ligand on three different linkers. The affinity of the prepared compounds to a library of human galectins was determined using competitive ELISA assay and biolayer interferometry. Structure-affinity relationships regarding the influence of the linker and the core structure were formulated. Substantial differences were found between various linker lengths and the position of the triazole unit. The formation of supramolecular clusters was detected by atomic force microscopy. The present work gives a systematic insight into prospective galectin ligands based on the calix[4]arene core.
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Affiliation(s)
- Dorota Konvalinková
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
| | - František Dolníček
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Michaela Hovorková
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic. .,Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, CZ-12843 Prague 2, Czech Republic
| | - Jakub Červený
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic. .,Department of Analytical Chemistry, Faculty of Science, Charles University, Hlavova 8, CZ-12843 Prague 2, Czech Republic
| | - Ondřej Kundrát
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Helena Pelantová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
| | - Lucie Petrásková
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
| | - Josef Cvačka
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic
| | - Margarita Faizulina
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Beena Varghese
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Petr Kovaříček
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Vladimír Křen
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic.
| | - Pavel Lhoták
- Department of Organic Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-16628 Praha 6, Czech Republic.
| | - Pavla Bojarová
- Institute of Microbiology of the Czech Academy of Sciences, Vídeňská 1083, CZ-14220 Prague 4, Czech Republic. .,Department of Health Care Disciplines and Population Protection, Faculty of Biomedical Engineering, Czech Technical University in Prague, nám. Sítná 3105, CZ-272 01 Kladno, Czech Republic
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4
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Forrester TJB, Ovchinnikova OG, Li Z, Kitova EN, Nothof JT, Koizumi A, Klassen JS, Lowary TL, Whitfield C, Kimber MS. The retaining β-Kdo glycosyltransferase WbbB uses a double-displacement mechanism with an intermediate adduct rearrangement step. Nat Commun 2022; 13:6277. [PMID: 36271007 PMCID: PMC9587256 DOI: 10.1038/s41467-022-33988-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 10/07/2022] [Indexed: 12/25/2022] Open
Abstract
WbbB, a lipopolysaccharide O-antigen synthesis enzyme from Raoultella terrigena, contains an N-terminal glycosyltransferase domain with a highly modified architecture that adds a terminal β-Kdo (3-deoxy-D-manno-oct-2-ulosonic acid) residue to the O-antigen saccharide, with retention of stereochemistry. We show, using mass spectrometry, that WbbB forms a covalent adduct between the catalytic nucleophile, Asp232, and Kdo. We also determine X-ray structures for the CMP-β-Kdo donor complex, for Kdo-adducts with D232N and D232C WbbB variants, for a synthetic disaccharide acceptor complex, and for a ternary complex with both a Kdo-adduct and the acceptor. Together, these structures show that the enzyme-linked Asp232-Kdo adduct rotates to reposition the Kdo into a second sub-site, which then transfers Kdo to the acceptor. Retaining glycosyltransferases were thought to use only the front-side SNi substitution mechanism; here we show that retaining glycosyltransferases can also potentially use double-displacement mechanisms, but incorporating an additional catalytic subsite requires rearrangement of the protein's architecture.
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Affiliation(s)
- Taylor J. B. Forrester
- grid.34429.380000 0004 1936 8198Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1 Canada
| | - Olga G. Ovchinnikova
- grid.34429.380000 0004 1936 8198Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1 Canada
| | - Zhixiong Li
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada
| | - Elena N. Kitova
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada
| | - Jeremy T. Nothof
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada
| | - Akihiko Koizumi
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada
| | - John S. Klassen
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada
| | - Todd L. Lowary
- grid.17089.370000 0001 2190 316XDepartment of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2 Canada ,grid.506934.d0000 0004 0633 7878Institute of Biological Chemistry, Academia Sinica, Academia Road, Section 2, #128, Nangang, Taipei, 11529 Taiwan ,grid.19188.390000 0004 0546 0241Institute of Biochemical Sciences, National Taiwan University, Section 4, #1, Roosevelt Road, Taipei, 10617 Taiwan
| | - Chris Whitfield
- grid.34429.380000 0004 1936 8198Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1 Canada
| | - Matthew S. Kimber
- grid.34429.380000 0004 1936 8198Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1 Canada
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5
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Characterization of genes in guar gum biosynthesis based on quantitative RNA-sequencing in guar bean (Cyamopsis tetragonoloba). Sci Rep 2019; 9:10991. [PMID: 31358893 PMCID: PMC6662795 DOI: 10.1038/s41598-019-47518-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 07/09/2019] [Indexed: 12/13/2022] Open
Abstract
Guar gum is an important raw material in the food, textile and oil industries, but the biosynthesis of guar gum remains unclear. To illuminate the genes involved in guar gum biosynthesis, guar beans from 30 and 40 days after flowering (DAF) were used for RNA sequencing in this study. A total of 2,535 and 2,724 preferentially expressed genes were found in 30 and 40 DAF endosperm, and 3,720 and 2,530 preferentially expressed genes were found in 30 and 40 DAF embryos, respectively. Of these, mannan synthase genes, α-galactosyltransferase genes and cellulose synthase genes were preferentially expressed in the endosperm from 30 and 40 DAF. The high expression level of these glycometabolism genes in endosperm is consistent with the expectation that the main component of guar gum is galactomannan. We believe that genes related to guar gum biosynthesis found in this study will be useful for both new variety development via genetic engineering and synthetic biology research on guar gum biosynthesis in the future.
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6
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Amos RA, Pattathil S, Yang JY, Atmodjo MA, Urbanowicz BR, Moremen KW, Mohnen D. A two-phase model for the non-processive biosynthesis of homogalacturonan polysaccharides by the GAUT1:GAUT7 complex. J Biol Chem 2018; 293:19047-19063. [PMID: 30327429 DOI: 10.1074/jbc.ra118.004463] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 10/08/2018] [Indexed: 11/06/2022] Open
Abstract
Homogalacturonan (HG) is a pectic glycan in the plant cell wall that contributes to plant growth and development and cell wall structure and function, and interacts with other glycans and proteoglycans in the wall. HG is synthesized by the galacturonosyltransferase (GAUT) gene family. Two members of this family, GAUT1 and GAUT7, form a heteromeric enzyme complex in Arabidopsis thaliana Here, we established a heterologous GAUT expression system in HEK293 cells and show that co-expression of recombinant GAUT1 with GAUT7 results in the production of a soluble GAUT1:GAUT7 complex that catalyzes elongation of HG products in vitro The reaction rates, progress curves, and product distributions exhibited major differences dependent upon small changes in the degree of polymerization (DP) of the oligosaccharide acceptor. GAUT1:GAUT7 displayed >45-fold increased catalytic efficiency with DP11 acceptors relative to DP7 acceptors. Although GAUT1:GAUT7 synthesized high-molecular-weight polymeric HG (>100 kDa) in a substrate concentration-dependent manner typical of distributive (nonprocessive) glycosyltransferases with DP11 acceptors, reactions primed with short-chain acceptors resulted in a bimodal product distribution of glycan products that has previously been reported as evidence for a processive model of GT elongation. As an alternative to the processive glycosyltransfer model, a two-phase distributive elongation model is proposed in which a slow phase, which includes the de novo initiation of HG and elongation of short-chain acceptors, is distinguished from a phase of rapid elongation of intermediate- and long-chain acceptors. Upon reaching a critical chain length of DP11, GAUT1:GAUT7 elongates HG to high-molecular-weight products.
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Affiliation(s)
- Robert A Amos
- From the Complex Carbohydrate Research Center and.,the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | | | | | - Melani A Atmodjo
- From the Complex Carbohydrate Research Center and.,the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | | | - Kelley W Moremen
- From the Complex Carbohydrate Research Center and.,the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Debra Mohnen
- From the Complex Carbohydrate Research Center and .,the Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
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7
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Culbertson AT, Ehrlich JJ, Choe JY, Honzatko RB, Zabotina OA. Structure of xyloglucan xylosyltransferase 1 reveals simple steric rules that define biological patterns of xyloglucan polymers. Proc Natl Acad Sci U S A 2018; 115:6064-6069. [PMID: 29784804 PMCID: PMC6003343 DOI: 10.1073/pnas.1801105115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The plant cell wall is primarily a polysaccharide mesh of the most abundant biopolymers on earth. Although one of the richest sources of biorenewable materials, the biosynthesis of the plant polysaccharides is poorly understood. Structures of many essential plant glycosyltransferases are unknown and suitable substrates are often unavailable for in vitro analysis. The dearth of such information impedes the development of plants better suited for industrial applications. Presented here are structures of Arabidopsis xyloglucan xylosyltransferase 1 (XXT1) without ligands and in complexes with UDP and cellohexaose. XXT1 initiates side-chain extensions from a linear glucan polymer by transferring the xylosyl group from UDP-xylose during xyloglucan biosynthesis. XXT1, a homodimer and member of the GT-A fold family of glycosyltransferases, binds UDP analogously to other GT-A fold enzymes. Structures here and the properties of mutant XXT1s are consistent with a SNi-like catalytic mechanism. Distinct from other systems is the recognition of cellohexaose by way of an extended cleft. The XXT1 dimer alone cannot produce xylosylation patterns observed for native xyloglucans because of steric constraints imposed by the acceptor binding cleft. Homology modeling of XXT2 and XXT5, the other two xylosyltransferases involved in xyloglucan biosynthesis, reveals a structurally altered cleft in XXT5 that could accommodate a partially xylosylated glucan chain produced by XXT1 and/or XXT2. An assembly of the three XXTs can produce the xylosylation patterns of native xyloglucans, suggesting the involvement of an organized multienzyme complex in the xyloglucan biosynthesis.
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Affiliation(s)
- Alan T Culbertson
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011
| | - Jacqueline J Ehrlich
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011
| | - Jun-Yong Choe
- Department of Biochemistry and Molecular Biology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064
| | - Richard B Honzatko
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011
| | - Olga A Zabotina
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, IA 50011;
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8
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Gagnon SML, Legg MSG, Sindhuwinata N, Letts JA, Johal AR, Schuman B, Borisova SN, Palcic MM, Peters T, Evans SV. High-resolution crystal structures and STD NMR mapping of human ABO(H) blood group glycosyltransferases in complex with trisaccharide reaction products suggest a molecular basis for product release. Glycobiology 2018; 27:966-977. [PMID: 28575295 DOI: 10.1093/glycob/cwx053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 05/31/2017] [Indexed: 11/12/2022] Open
Abstract
The human ABO(H) blood group A- and B-synthesizing glycosyltransferases GTA and GTB have been structurally characterized to high resolution in complex with their respective trisaccharide antigen products. These findings are particularly timely and relevant given the dearth of glycosyltransferase structures collected in complex with their saccharide reaction products. GTA and GTB utilize the same acceptor substrates, oligosaccharides terminating with α-l-Fucp-(1→2)-β-d-Galp-OR (where R is a glycolipid or glycoprotein), but use distinct UDP donor sugars, UDP-N-acetylgalactosamine and UDP-galactose, to generate the blood group A (α-l-Fucp-(1→2)[α-d-GalNAcp-(1→3)]-β-d-Galp-OR) and blood group B (α-l-Fucp-(1→2)[α-d-Galp-(1→3)]-β-d-Galp-OR) determinant structures, respectively. Structures of GTA and GTB in complex with their respective trisaccharide products reveal a conflict between the transferred sugar monosaccharide and the β-phosphate of the UDP donor. Mapping of the binding epitopes by saturation transfer difference NMR measurements yielded data consistent with the X-ray structural results. Taken together these data suggest a mechanism of product release where monosaccharide transfer to the H-antigen acceptor induces active site disorder and ejection of the UDP leaving group prior to trisaccharide egress.
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Affiliation(s)
- Susannah M L Gagnon
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Max S G Legg
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Nora Sindhuwinata
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - James A Letts
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Asha R Johal
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Brock Schuman
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Svetlana N Borisova
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Monica M Palcic
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6.,Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Thomas Peters
- Institute of Chemistry, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Stephen V Evans
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
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9
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Dauner M, Batroff E, Bachmann V, Hauck CR, Wittmann V. Synthetic Glycosphingolipids for Live-Cell Labeling. Bioconjug Chem 2016; 27:1624-37. [PMID: 27253729 DOI: 10.1021/acs.bioconjchem.6b00177] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glycosphingolipids are an important component of cell membranes that are involved in many biological processes. Fluorescently labeled glycosphingolipids are frequently used to gain insight into their localization. However, the attachment of a fluorophore to the glycan part or-more commonly-to the lipid part of glycosphingolipids is known to alter the biophysical properties and can perturb the biological function of the probe. Presented here is the synthesis of novel glycosphingolipid probes with mono- and disaccharide head groups and ceramide moieties containing fatty acids of varying chain length (C4 to C20). These glycosphingolipids bear an azide or an alkyne group as chemical reporter to which a fluorophore can be attached through a bioorthogonal ligation reaction. The fluorescent tag and any linker connected to it can be chosen in a flexible manner. We demonstrate the suitability of the probes by selective visualization of the plasma membrane of living cells by confocal microscopy techniques. Whereas the derivatives with the shorter fatty acids can be directly applied to HEK 293T cells, the hydrophobic glycosphingolipids with longer fatty acids can be delivered to cells using fusogenic liposomes.
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Affiliation(s)
- Martin Dauner
- Department of Chemistry and ‡Department of Biology, Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
| | - Ellen Batroff
- Department of Chemistry and ‡Department of Biology, Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
| | - Verena Bachmann
- Department of Chemistry and ‡Department of Biology, Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
| | - Christof R Hauck
- Department of Chemistry and ‡Department of Biology, Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
| | - Valentin Wittmann
- Department of Chemistry and ‡Department of Biology, Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz , 78457 Konstanz, Germany
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10
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Abstract
The article reviews the significant contributions to, and the present status of, applications of computational methods for the characterization and prediction of protein-carbohydrate interactions. After a presentation of the specific features of carbohydrate modeling, along with a brief description of the experimental data and general features of carbohydrate-protein interactions, the survey provides a thorough coverage of the available computational methods and tools. At the quantum-mechanical level, the use of both molecular orbitals and density-functional theory is critically assessed. These are followed by a presentation and critical evaluation of the applications of semiempirical and empirical methods: QM/MM, molecular dynamics, free-energy calculations, metadynamics, molecular robotics, and others. The usefulness of molecular docking in structural glycobiology is evaluated by considering recent docking- validation studies on a range of protein targets. The range of applications of these theoretical methods provides insights into the structural, energetic, and mechanistic facets that occur in the course of the recognition processes. Selected examples are provided to exemplify the usefulness and the present limitations of these computational methods in their ability to assist in elucidation of the structural basis underlying the diverse function and biological roles of carbohydrates in their dialogue with proteins. These test cases cover the field of both carbohydrate biosynthesis and glycosyltransferases, as well as glycoside hydrolases. The phenomenon of (macro)molecular recognition is illustrated for the interactions of carbohydrates with such proteins as lectins, monoclonal antibodies, GAG-binding proteins, porins, and viruses.
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Affiliation(s)
- Serge Pérez
- Department of Molecular Pharmacochemistry, CNRS, University Grenoble-Alpes, Grenoble, France.
| | - Igor Tvaroška
- Department of Chemistry, Slovak Academy of Sciences, Bratislava, Slovak Republic; Department of Chemistry, Faculty of Natural Sciences, Constantine The Philosopher University, Nitra, Slovak Republic.
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11
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Tvaroška I. Atomistic insight into the catalytic mechanism of glycosyltransferases by combined quantum mechanics/molecular mechanics (QM/MM) methods. Carbohydr Res 2015; 403:38-47. [DOI: 10.1016/j.carres.2014.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 06/12/2014] [Accepted: 06/16/2014] [Indexed: 01/17/2023]
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12
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Padungros P, Fan RH, Casselman MD, Cheng G, Khatri HR, Wei A. Synthesis and reactivity of 4'-deoxypentenosyl disaccharides. J Org Chem 2014; 79:4878-91. [PMID: 24797640 PMCID: PMC4059249 DOI: 10.1021/jo500449h] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Indexed: 11/29/2022]
Abstract
4-Deoxypentenosides (4-DPs) are versatile synthons for rare or higher-order pyranosides, and they provide an entry for structural diversification at the C5 position. Previous studies have shown that 4-DPs undergo stereocontrolled DMDO oxidation; subsequent epoxide ring-openings with various nucleophiles can proceed with both anti or syn selectivity. Here, we report the synthesis of α- and β-linked 4'-deoxypentenosyl (4'-DP) disaccharides, and we investigate their post-glycosylational C5' additions using the DMDO oxidation/ring-opening sequence. The α-linked 4'-DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf2O activation, whereas β-linked 4'-DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both α- and β-linked 4'-DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the α-epoxypentenosides could be successfully converted into terminal l-iduronic acids via the syn addition of 2-furylzinc bromide. These studies support a novel approach to oligosaccharide synthesis, in which the stereochemical configuration of the terminal 4'-DP unit is established at a post-glycosylative stage.
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Affiliation(s)
| | | | - Matthew D. Casselman
- Department of Chemistry, Purdue
University, 560 Oval
Drive, West Lafayette, Indiana 47907-2084, United States
| | - Gang Cheng
- Department of Chemistry, Purdue
University, 560 Oval
Drive, West Lafayette, Indiana 47907-2084, United States
| | - Hari R. Khatri
- Department of Chemistry, Purdue
University, 560 Oval
Drive, West Lafayette, Indiana 47907-2084, United States
| | - Alexander Wei
- Department of Chemistry, Purdue
University, 560 Oval
Drive, West Lafayette, Indiana 47907-2084, United States
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13
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Kooy FK, Beeftink HH, Eppink MH, Tramper J, Eggink G, Boeriu CG. Kinetic and structural analysis of two transferase domains in Pasteurella multocida hyaluronan synthase. ACTA ACUST UNITED AC 2014. [DOI: 10.1016/j.molcatb.2014.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Chan PHW, Cheung AH, Okon M, Chen HM, Withers SG, McIntosh LP. Investigating the Structural Dynamics of α-1,4-Galactosyltransferase C from Neisseria meningitidis by Nuclear Magnetic Resonance Spectroscopy. Biochemistry 2013; 52:320-32. [DOI: 10.1021/bi301317d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Patrick H. W. Chan
- Department of Biochemistry and
Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Centre for High-throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4,
Canada
| | - Adrienne H. Cheung
- Department of Biochemistry and
Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Mark Okon
- Department of Biochemistry and
Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1,
Canada
| | - Hong-Ming Chen
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1,
Canada
| | - Stephen G. Withers
- Department of Biochemistry and
Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Centre for High-throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4,
Canada
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1,
Canada
| | - Lawrence P. McIntosh
- Department of Biochemistry and
Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
- Centre for High-throughput Biology, University of British Columbia, Vancouver, BC V6T 1Z4,
Canada
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1,
Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4,
Canada
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15
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Chan PHW, Weissbach S, Okon M, Withers SG, McIntosh LP. Nuclear magnetic resonance spectral assignments of α-1,4-galactosyltransferase LgtC from Neisseria meningitidis: substrate binding and multiple conformational states. Biochemistry 2012; 51:8278-92. [PMID: 22992161 DOI: 10.1021/bi3010279] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Lipopolysaccharide α-1,4-galactosyltransferase C (LgtC) from Neisseria meningitidis is responsible for a key step in lipooligosaccharide biosynthesis involving the transfer of α-galactose from the sugar donor UDP-galactose to a terminal acceptor lactose. Crystal structures of the complexes of LgtC with Mn(2+) and the sugar donor analogue UDP-2-deoxy-2-fluorogalactose in the absence and presence of the sugar acceptor analogue 4'-deoxylactose provided key insights into the galactosyl-transfer mechanism. Combined with kinetic analyses, the enzymatic mechanism of LgtC appears to involve a "front-side attack" S(N)i-like mechanism with a short-lived oxocarbenium-phosphate ion pair intermediate. As a prerequisite for investigating the required roles of structural dynamics in this catalytic mechanism by nuclear magnetic resonance techniques, the transverse relaxation-optimized amide (15)N heteronuclear single-quantum correlation and methyl (13)C heteronuclear multiple-quantum correlation spectra of LgtC in its apo, substrate analogue, and product complexes were partially assigned. This was accomplished using a suite of complementary spectroscopic approaches, combined with selective isotopic labeling and mutagenesis of all the isoleucine residues in the protein. Only ~70% of the amide signals could be detected, whereas more than the expected number of methyl signals were observed, indicating that LgtC adopts multiple interconverting conformational states. Chemical shift perturbation mapping provided insights into substrate and product binding, including the demonstration that the sugar donor analogue (UDP-2FGal) associates with LgtC only in the presence of a metal ion (Mg(2+)). These spectral assignments provide the foundation for detailed studies of the conformational dynamics of LgtC.
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Affiliation(s)
- Patrick H W Chan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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16
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Díaz A, Díaz-Lobo M, Grados E, Guinovart JJ, Fita I, Ferrer JC. Lyase activity of glycogen synthase: Is an elimination/addition mechanism a possible reaction pathway for retaining glycosyltransferases? IUBMB Life 2012; 64:649-58. [PMID: 22648728 DOI: 10.1002/iub.1048] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 04/05/2012] [Indexed: 11/10/2022]
Abstract
Despite the biological relevance of glycosyltrasferases (GTs) and the many efforts devoted to this subject, the catalytic mechanism through which a subclass of this large family of enzymes, namely those that operate with net retention of the anomeric configuration, has not been fully established. Here, we show that in the absence of an acceptor, an archetypal retaining GT such as Pyrococcus abyssi glycogen synthase (PaGS) reacts with its glucosyl donor substrate, uridine 5'-diphosphoglucose (UDP-Glc), to produce the scission of the covalent bond between the terminal phosphate oxygen of UDP and the sugar ring. X-ray diffraction analysis of the PaGS/UDP-Glc complex shows no electronic density attributable to the UDP moiety, but establishes the presence in the active site of the enzyme of a glucose-like derivative that lacks the exocyclic oxygen attached to the anomeric carbon. Chemical derivatization followed by gas chromatography/mass spectrometry of the isolated glucose-like species allowed us to identify the molecule found in the catalytic site of PaGS as 1,5-anhydro-D-arabino-hex-1-enitol (AA) or its tautomeric form, 1,5-anhydro-D-fructose. These findings are consistent with a stepwise S(N) i-like mechanism as the modus operandi of retaining GTs, a mechanism that involves the discrete existence of an oxocarbenium intermediate. Even in the absence of a glucosyl acceptor, glycogen synthase (GS) promotes the formation of the cationic intermediate, which, by eliminating the proton of the adjacent C2 carbon atom, yields AA. Alternatively, these observations could be interpreted assuming that AA is a true intermediate in the reaction pathway of GS and that this enzyme operates through an elimination/addition mechanism.
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Affiliation(s)
- Adelaida Díaz
- Institute for Research in Biomedicine, IRB Barcelona
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17
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Urresti S, Albesa-Jové D, Schaeffer F, Pham HT, Kaur D, Gest P, van der Woerd MJ, Carreras-González A, López-Fernández S, Alzari PM, Brennan PJ, Jackson M, Guerin ME. Mechanistic insights into the retaining glucosyl-3-phosphoglycerate synthase from mycobacteria. J Biol Chem 2012; 287:24649-61. [PMID: 22637481 DOI: 10.1074/jbc.m112.368191] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Considerable progress has been made in recent years in our understanding of the structural basis of glycosyl transfer. Yet the nature and relevance of the conformational changes associated with substrate recognition and catalysis remain poorly understood. We have focused on the glucosyl-3-phosphoglycerate synthase (GpgS), a "retaining" enzyme, that initiates the biosynthetic pathway of methylglucose lipopolysaccharides in mycobacteria. Evidence is provided that GpgS displays an unusually broad metal ion specificity for a GT-A enzyme, with Mg(2+), Mn(2+), Ca(2+), Co(2+), and Fe(2+) assisting catalysis. In the crystal structure of the apo-form of GpgS, we have observed that a flexible loop adopts a double conformation L(A) and L(I) in the active site of both monomers of the protein dimer. Notably, the L(A) loop geometry corresponds to an active conformation and is conserved in two other relevant states of the enzyme, namely the GpgS·metal·nucleotide sugar donor and the GpgS·metal·nucleotide·acceptor-bound complexes, indicating that GpgS is intrinsically in a catalytically active conformation. The crystal structure of GpgS in the presence of Mn(2+)·UDP·phosphoglyceric acid revealed an alternate conformation for the nucleotide sugar β-phosphate, which likely occurs upon sugar transfer. Structural, biochemical, and biophysical data point to a crucial role of the β-phosphate in donor and acceptor substrate binding and catalysis. Altogether, our experimental data suggest a model wherein the catalytic site is essentially preformed, with a few conformational changes of lateral chain residues as the protein proceeds along the catalytic cycle. This model of action may be applicable to a broad range of GT-A glycosyltransferases.
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Affiliation(s)
- Saioa Urresti
- Unidad de Biofísica, Centro Mixto Consejo Superior de Investigaciones Científicas-Universidad del País Vasco/Euskal Herriko Unibertsitatea, Barrio Sarriena s/n, Leioa, Bizkaia, 48940, Spain
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18
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Durantie E, Bucher C, Gilmour R. Fluorine-directed β-galactosylation: chemical glycosylation development by molecular editing. Chemistry 2012; 18:8208-15. [PMID: 22592962 DOI: 10.1002/chem.201200468] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Indexed: 11/10/2022]
Abstract
Validation of the 2-fluoro substituent as an inert steering group to control chemical glycosylation is presented. A molecular editing study has revealed that the exceptional levels of diastereocontrol in glycosylation processes by using 2-fluoro-3,4,6-tri-O-benzyl glucopyranosyl trichloroacetimidate (TCA) scaffolds are a consequence of the 2R,3S,4S stereotriad. This study has also revealed that epimerization at C4, results in a substantial enhancement in β-selectivity (up to β/α 300:1).
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Affiliation(s)
- Estelle Durantie
- Laboratory for Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland
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19
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Gómez H, Polyak I, Thiel W, Lluch JM, Masgrau L. Retaining Glycosyltransferase Mechanism Studied by QM/MM Methods: Lipopolysaccharyl-α-1,4-galactosyltransferase C Transfers α-Galactose via an Oxocarbenium Ion-like Transition State. J Am Chem Soc 2012; 134:4743-52. [DOI: 10.1021/ja210490f] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Iakov Polyak
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an
der Ruhr, Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim an
der Ruhr, Germany
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20
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Lee SS, Hong SY, Errey JC, Izumi A, Davies GJ, Davis BG. Mechanistic evidence for a front-side, SNi-type reaction in a retaining glycosyltransferase. Nat Chem Biol 2011; 7:631-8. [DOI: 10.1038/nchembio.628] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Accepted: 06/10/2011] [Indexed: 01/14/2023]
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21
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Lee HJ, Lairson LL, Rich JR, Lameignere E, Wakarchuk WW, Withers SG, Strynadka NCJ. Structural and kinetic analysis of substrate binding to the sialyltransferase Cst-II from Campylobacter jejuni. J Biol Chem 2011; 286:35922-35932. [PMID: 21832050 DOI: 10.1074/jbc.m111.261172] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sialic acids play important roles in various biological processes and typically terminate the oligosaccharide chains on the cell surfaces of a wide range of organisms, including mammals and bacteria. Their attachment is catalyzed by a set of sialyltransferases with defined specificities both for their acceptor sugars and the position of attachment. However, little is known of how this specificity is encoded. The structure of the bifunctional sialyltransferase Cst-II of the human pathogen Campylobacter jejuni in complex with CMP and the terminal trisaccharide of its natural acceptor (Neu5Ac-α-2,3-Gal-β-1,3-GalNAc) has been solved at 1.95 Å resolution, and its kinetic mechanism was shown to be iso-ordered Bi Bi, consistent with its dual acceptor substrate specificity. The trisaccharide acceptor is seen to bind to the active site of Cst-II through interactions primarily mediated by Asn-51, Tyr-81, and Arg-129. Kinetic and structural analyses of mutants modified at these positions indicate that these residues are critical for acceptor binding and catalysis, thereby providing significant new insight into the kinetic and catalytic mechanism, and acceptor specificity of this pathogen-encoded bifunctional GT-42 sialyltransferase.
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Affiliation(s)
- Ho Jun Lee
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3; Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3
| | - Luke L Lairson
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1
| | - Jamie R Rich
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1
| | - Emilie Lameignere
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3; Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3
| | - Warren W Wakarchuk
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Stephen G Withers
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3; Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1; Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3; Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3; Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia V6T 1Z4.
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22
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Spadiut O, Ibatullin FM, Peart J, Gullfot F, Martinez-Fleites C, Ruda M, Xu C, Sundqvist G, Davies GJ, Brumer H. Building custom polysaccharides in vitro with an efficient, broad-specificity xyloglucan glycosynthase and a fucosyltransferase. J Am Chem Soc 2011; 133:10892-900. [PMID: 21618981 PMCID: PMC3135005 DOI: 10.1021/ja202788q] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Indexed: 11/29/2022]
Abstract
The current drive for applications of biomass-derived compounds, for energy and advanced materials, has led to a resurgence of interest in the manipulation of plant polymers. The xyloglucans, a family of structurally complex plant polysaccharides, have attracted significant interest due to their intrinsic high affinity for cellulose, both in muro and in technical applications. Moreover, current cell wall models are limited by the lack of detailed structure-property relationships of xyloglucans, due to a lack of molecules with well-defined branching patterns. Here, we have developed a new, broad-specificity "xyloglucan glycosynthase", selected from active-site mutants of a bacterial endoxyloglucanase, which catalyzed the synthesis of high molar mass polysaccharides, with complex side-chain structures, from suitable glycosyl fluoride donor substrates. The product range was further extended by combination with an Arabidopsis thaliana α(1→2)-fucosyltransferase to achieve the in vitro synthesis of fucosylated xyloglucans typical of dicot primary cell walls. These enzymes thus comprise a toolkit for the controlled enzymatic synthesis of xyloglucans that are otherwise impossible to obtain from native sources. Moreover, this study demonstrates the validity of a chemo-enzymatic approach to polysaccharide synthesis, in which the simplicity and economy of glycosynthase technology is harnessed together with the exquisite specificity of glycosyltransferases to control molecular complexity.
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Affiliation(s)
- Oliver Spadiut
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
- Wallenberg Wood Science Center, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
| | - Farid M. Ibatullin
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
| | - Jonelle Peart
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
| | - Fredrika Gullfot
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
| | - Carlos Martinez-Fleites
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Marcus Ruda
- Swetree Technologies AB, P.O. Box 4095, 904 03 Umeå, Sweden
| | - Chunlin Xu
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
- Wallenberg Wood Science Center, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
| | - Gustav Sundqvist
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
| | - Gideon J. Davies
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Harry Brumer
- Division of Glycoscience, School of Biotechnology, Royal Institute of Technology (KTH), 106 91 Stockholm, Sweden
- Wallenberg Wood Science Center, Royal Institute of Technology (KTH), 100 44 Stockholm, Sweden
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23
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Xu Y, Fan H, Lu C, Gao GF, Li X. Synthesis of galabiose-chitosan conjugate as potent inhibitor of Streptococcus suis adhesion. Biomacromolecules 2010; 11:1701-4. [PMID: 20540558 DOI: 10.1021/bm100289v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of this work is to construct a safe and effective drug candidate against Streptococcus suis infection. A panel of chitosan-based polymer conjugates with branched galabiose (Galalpha1-4Gal) side chains was synthesized as inhibitors of S. suis adhesion. The synthesis was achieved by using an aldehyde-functionalized galabiose derivative to graft it onto chitosan amino groups. Structural compositions of the conjugates were verified by 1H NMR spectroscopy and CHN elemental analyses. Potent inhibitory activities of the conjugates against S. suis adhesion to human erythrocytes were determined at low nanomolar concentration by HAI assay. An SPR study revealed a high affinity binding (Kd=39.6 nM) of the conjugate with BSI-B4 lectin. By using biocompatible chitosan as the scaffold for presenting S. suis -specific galabiose units, as well as the concise route tailored for the conjugate syntheses, the present study provides a practical way for explorations of new anti- S. suis therapies.
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Affiliation(s)
- Yaozu Xu
- Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100190, China
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24
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Esmurziev AM, Simic N, Hoff BH, Sundby E. Synthesis and Structure Elucidation of Benzoylated Deoxyfluoropyranosides. J Carbohydr Chem 2010. [DOI: 10.1080/07328303.2010.540055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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Sindhuwinata N, Munoz E, Munoz FJ, Palcic MM, Peters H, Peters T. Binding of an acceptor substrate analog enhances the enzymatic activity of human blood group B galactosyltransferase. Glycobiology 2010; 20:718-23. [PMID: 20154292 DOI: 10.1093/glycob/cwq019] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The hydrolysis of the donor substrate uridine diphosphate galactose (UDP-Gal) by human blood group B galactosyltransferase (GTB) has been followed by nuclear magnetic resonance in the presence and in the absence of an acceptor substrate analog. It is observed that the presence of the acceptor substrate analog promotes hydrolysis of UDP-Gal. Subsequent analysis of the kinetics of the enzymatic hydrolysis suggests that this effect is due to an increased affinity of GTB for UDP-Gal in the presence of the acceptor analog. Isothermal titration calorimetry experiments substantiate this conclusion. As hydrolysis may be understood as a glycosyl transfer reaction where water serves as universal acceptor, we suggest that in general the binding of acceptor substrates to retaining glycosyltransferases modulates the rate of glycosyl transfer. In fact, this may point to a general mechanism used by retaining glycosyltransferases to discriminate acceptor substrates under physiological conditions.
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Affiliation(s)
- Nora Sindhuwinata
- Institute of Chemistry, University of Luebeck, Ratzeburger Allee 160, 23538 Luebeck Germany
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26
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Goedl C, Nidetzky B. Sucrose Phosphorylase Harbouring a Redesigned, Glycosyltransferase-Like Active Site Exhibits Retaining Glucosyl Transfer in the Absence of a Covalent Intermediate. Chembiochem 2009; 10:2333-7. [DOI: 10.1002/cbic.200900429] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Krupyanko VI. Perspectives of data analysis of enzyme inhibition and activation, Part 3: Equations for calculation of the initial rates of enzymatic reactions. J Biochem Mol Toxicol 2009; 23:108-18. [PMID: 19367644 DOI: 10.1002/jbt.20271] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Equations for calculation of the initial rates of activated enzymatic reactions and the inhibited enzymatic reactions, unavailable in experimental enzymology, were obtained. Examples of practically using of these equations are given.
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Affiliation(s)
- Vladimir I Krupyanko
- G. K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russia.
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28
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Ronchi P, Vignando S, Guglieri S, Polito L, Lay L. Exploiting the cross-metathesis reaction in the synthesis of pseudo-oligosaccharides. Org Biomol Chem 2009; 7:2635-44. [DOI: 10.1039/b822989a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Thibodeaux C, Melançon C, Liu HW. Biosynthese von Naturstoffzuckern und enzymatische Glycodiversifizierung. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200801204] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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30
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Lairson LL, Henrissat B, Davies GJ, Withers SG. Glycosyltransferases: structures, functions, and mechanisms. Annu Rev Biochem 2008; 77:521-55. [PMID: 18518825 DOI: 10.1146/annurev.biochem.76.061005.092322] [Citation(s) in RCA: 1370] [Impact Index Per Article: 85.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Glycosyltransferases catalyze glycosidic bond formation using sugar donors containing a nucleoside phosphate or a lipid phosphate leaving group. Only two structural folds, GT-A and GT-B, have been identified for the nucleotide sugar-dependent enzymes, but other folds are now appearing for the soluble domains of lipid phosphosugar-dependent glycosyl transferases. Structural and kinetic studies have provided new insights. Inverting glycosyltransferases utilize a direct displacement S(N)2-like mechanism involving an enzymatic base catalyst. Leaving group departure in GT-A fold enzymes is typically facilitated via a coordinated divalent cation, whereas GT-B fold enzymes instead use positively charged side chains and/or hydroxyls and helix dipoles. The mechanism of retaining glycosyltransferases is less clear. The expected two-step double-displacement mechanism is rendered less likely by the lack of conserved architecture in the region where a catalytic nucleophile would be expected. A mechanism involving a short-lived oxocarbenium ion intermediate now seems the most likely, with the leaving phosphate serving as the base.
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Affiliation(s)
- L L Lairson
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada.
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31
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Lee H, Wang P, Hoshino H, Ito Y, Kobayashi M, Nakayama J, Seeberger PH, Fukuda M. Alpha1,4GlcNAc-capped mucin-type O-glycan inhibits cholesterol alpha-glucosyltransferase from Helicobacter pylori and suppresses H. pylori growth. Glycobiology 2008; 18:549-58. [PMID: 18458030 DOI: 10.1093/glycob/cwn037] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori infects over half of the world's population and is thought to be a leading cause of gastric ulcer, gastric carcinoma, and gastric malignant lymphoma of mucosa-associated lymphoid tissue type. Previously, we reported that a gland mucin (MUC6) present in the lower portion of the gastric mucosa containing alpha1,4-N-acetylglucosamine (alpha1,4GlcNAc)-capped core 2-branched O-glycans suppresses H. pylori growth by inhibiting the synthesis of alpha-glucosyl cholesterol, a major constituent of the H. pylori cell wall (Kawakubo et al. 2004. Science. 305:1003-1006). Therefore, we cloned the genomic DNA encoding cholesterol alpha-glucosyltransferase (HP0421) and expressed its soluble form in Escherichia coli. Using this soluble HP0421, we show herein that HP0421 sequentially acts on uridine diphosphoglucose and cholesterol in an ordered Bi-Bi manner. We found that competitive inhibition of HP0421 by alpha1,4GlcNAc-capped core 2-branched O-glycan is much more efficient than noncompetitive inhibition by newly synthesized alpha-glucosyl cholesterol. Utilizing synthetic oligosaccharides, alpha-glucosyl cholesterol, and monosaccharides, we found that alpha1,4GlcNAc-capped core 2-branched O-glycan most efficiently inhibits H. pylori growth. These findings together indicate that alpha1,4GlcNAc-capped O-glycans suppress H. pylori growth by inhibiting HP0421, and that alpha1,4GlcNAc-capped core 2 O-glycans may be useful to treat patients infected with H. pylori.
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Affiliation(s)
- Heeseob Lee
- Tumor Microenvironment Program, Glycobiology Unit, Cancer Center, Burnham Institute for Medical Research, La Jolla, CA 92037, USA
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32
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Thibodeaux CJ, Melançon CE, Liu HW. Natural-product sugar biosynthesis and enzymatic glycodiversification. Angew Chem Int Ed Engl 2008; 47:9814-59. [PMID: 19058170 PMCID: PMC2796923 DOI: 10.1002/anie.200801204] [Citation(s) in RCA: 320] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Many biologically active small-molecule natural products produced by microorganisms derive their activities from sugar substituents. Changing the structures of these sugars can have a profound impact on the biological properties of the parent compounds. This realization has inspired attempts to derivatize the sugar moieties of these natural products through exploitation of the sugar biosynthetic machinery. This approach requires an understanding of the biosynthetic pathway of each target sugar and detailed mechanistic knowledge of the key enzymes. Scientists have begun to unravel the biosynthetic logic behind the assembly of many glycosylated natural products and have found that a core set of enzyme activities is mixed and matched to synthesize the diverse sugar structures observed in nature. Remarkably, many of these sugar biosynthetic enzymes and glycosyltransferases also exhibit relaxed substrate specificity. The promiscuity of these enzymes has prompted efforts to modify the sugar structures and alter the glycosylation patterns of natural products through metabolic pathway engineering and enzymatic glycodiversification. In applied biomedical research, these studies will enable the development of new glycosylation tools and generate novel glycoforms of secondary metabolites with useful biological activity.
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Affiliation(s)
- Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Charles E. Melançon
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX. (USA), 78712
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33
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Whitfield DM. DFT studies of the ionization of alpha and beta glycopyranosyl donors. Carbohydr Res 2007; 342:1726-40. [PMID: 17555731 DOI: 10.1016/j.carres.2007.05.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 04/26/2007] [Accepted: 05/06/2007] [Indexed: 11/28/2022]
Abstract
Current attempts at mimicking the transition states (TSs) of glycosyl processing enzymes (GPEs) that proceed through TSs with a high degree of oxacarbenium ion formation suffer from a paucity of data about the conformations of such oxacarbenium ions. Because TSs are maxima, the current models based on minimized structures may need some refinement. As part of studies directed at optimizing chemical glycosylation the ionization of 3,4,6-tri-O-acetyl-alpha/beta-D-glucopyranosyl chlorides and triflates, 2,3,4,6-tetra-O-methyl-alpha/beta-D-glucopyranosyl fluorides, chlorides and triflates, 2,3,4,6-tetra-O-methyl-alpha/beta-D-mannopyranosyl fluorides, 2,3-di-O-methyl 4,6-O-benzylidene alpha/beta-D-mannopyranosyl triflates and 2,3-di-O-methyl 4,6-O-benzylidene alpha/beta-D-glucopyranosyl triflates was studied by a prototypic density functional theory (DFT) procedure. In all cases, the alpha-anomers ionized smoothly to 4H3 half chair conformations or adjacent envelopes. By contrast, all beta-anomers exhibited an abrupt conformational change before ionization was complete. The nature of the conformations sampled depends on both the leaving group and the protecting group. The methods presented can be readily adapted to the study of any GPE or chemical glycosylation and provide a method for initial evaluation of plausible TSs, which in turn can be used in mimetic design.
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Affiliation(s)
- Dennis M Whitfield
- Institute for Biological Sciences, NRC Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6.
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34
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Thibodeaux CJ, Melançon CE, Liu HW. Unusual sugar biosynthesis and natural product glycodiversification. Nature 2007; 446:1008-16. [PMID: 17460661 DOI: 10.1038/nature05814] [Citation(s) in RCA: 250] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The enzymes involved in the biosynthesis of carbohydrates and the attachment of sugar units to biological acceptor molecules catalyse an array of chemical transformations and coupling reactions. In prokaryotes, both common sugar precursors and their enzymatically modified derivatives often become substituents of biologically active natural products through the action of glycosyltransferases. Recently, researchers have begun to harness the power of these biological catalysts to alter the sugar structures and glycosylation patterns of natural products both in vivo and in vitro. Biochemical and structural studies of sugar biosynthetic enzymes and glycosyltransferases, coupled with advances in bioengineering methodology, have ushered in a new era of drug development.
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Affiliation(s)
- Christopher J Thibodeaux
- Institute for Cellular and Molecular Biology, 1 University Station A4810, University of Texas at Austin, Austin, Texas 78712, USA
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35
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Krupa JC, Shaya D, Chi L, Linhardt RJ, Cygler M, Withers SG, Mort JS. Quantitative continuous assay for hyaluronan synthase. Anal Biochem 2006; 361:218-25. [PMID: 17173853 PMCID: PMC4114249 DOI: 10.1016/j.ab.2006.11.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 10/20/2006] [Accepted: 11/03/2006] [Indexed: 01/15/2023]
Abstract
A rapid, continuous, and convenient three-enzyme coupled UV absorption assay was developed to quantitate the glucuronic acid and N-acetylglucosamine transferase activities of hyaluronan synthase from Pasteurella multocida (PmHAS). Activity was measured by coupling the UDP produced from the PmHAS-catalyzed transfer of UDP-GlcNAc and UDP-GlcUA to a hyaluronic acid tetrasaccharide primer with the oxidation of NADH. Using a fluorescently labeled primer, the products were characterized by gel electrophoresis. Our results show that a truncated soluble form of recombinant PmHAS (residues 1-703) can catalyze the glycosyl transfers in a time- and concentration-dependent manner. The assay can be used to determine kinetic parameters, inhibition constants, and mechanistic aspects of this enzyme. In addition, it can be used to quantify PmHAS during purification of the enzyme from culture media.
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Affiliation(s)
- Joanne C. Krupa
- Joint Diseases Laboratory, Shriners Hospital for Children, Montreal, Que., Canada H3G 1A6
| | - David Shaya
- Department of Biochemistry, McGill University, Montreal, Que., Canada H3G 1Y6
| | - Lianli Chi
- Rensselaer Polytechnic Institute, Biotechnology Center 4005, Troy, NY 12180, USA
| | - Robert J. Linhardt
- Rensselaer Polytechnic Institute, Biotechnology Center 4005, Troy, NY 12180, USA
| | - Miroslaw Cygler
- Department of Biochemistry, McGill University, Montreal, Que., Canada H3G 1Y6
- Biotechnology Research Institute, NRC, Montreal, Que., Canada H4P 2R2
| | - Stephen G. Withers
- Department of Chemistry, University of British Columbia, Vancouver, BC, Canada V6T 1Z1
| | - John S. Mort
- Joint Diseases Laboratory, Shriners Hospital for Children, Montreal, Que., Canada H3G 1A6
- Department of Surgery, McGill University, Montreal, Que., Canada H3G 1A4
- Corresponding author. Fax: +1 514 842 5581. (J.S. Mort)
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36
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Lairson LL, Watts AG, Wakarchuk WW, Withers SG. Using substrate engineering to harness enzymatic promiscuity and expand biological catalysis. Nat Chem Biol 2006; 2:724-8. [PMID: 17057723 DOI: 10.1038/nchembio828] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Accepted: 09/11/2006] [Indexed: 11/09/2022]
Abstract
Despite their unparalleled catalytic prowess and environmental compatibility, enzymes have yet to see widespread application in synthetic chemistry. This lack of application and the resulting underuse of their enormous potential stems not only from a wariness about aqueous biological catalysis on the part of the typical synthetic chemist but also from limitations on enzyme applicability that arise from the high degree of substrate specificity possessed by most enzymes. This latter perceived limitation is being successfully challenged through rational protein engineering and directed evolution efforts to alter substrate specificity. However, such programs require considerable effort to establish. Here we report an alternative strategy for expanding the substrate specificity, and therefore the synthetic utility, of a given enzyme through a process of "substrate engineering". The attachment of a readily removable functional group to an alternative glycosyltransferase substrate induces a productive binding mode, facilitating rational control of substrate specificity and regioselectivity using wild-type enzymes.
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37
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Goedl C, Griessler R, Schwarz A, Nidetzky B. Structure-function relationships for Schizophyllum commune trehalose phosphorylase and their implications for the catalytic mechanism of family GT-4 glycosyltransferases. Biochem J 2006; 397:491-500. [PMID: 16640506 PMCID: PMC1533306 DOI: 10.1042/bj20060029] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The cDNA encoding trehalose phosphorylase, a family GT-4 glycosyltransferase from the fungus Schizophyllum commune, was isolated and expressed in Escherichia coli to yield functional recombinant protein in its full length of 737 amino acids. Unlike the natural phosphorylase that was previously obtained as a truncated 61 kDa monomer containing one tightly bound Mg2+, the intact enzyme produced in E. coli is a dimer and not associated with metal ions [Eis, Watkins, Prohaska and Nidetzky (2001) Biochem. J. 356, 757-767]. MS analysis of the slow spontaneous conversion of the full-length enzyme into a 61 kDa fragment that is fully active revealed that critical elements of catalysis and specificity of trehalose phosphorylase reside entirely in the C-terminal protein part. Intact and truncated phosphorylases thus show identical inhibition constants for the transition state analogue orthovanadate and alpha,alpha-trehalose (K(i) approximately 1 microM). Structure-based sequence comparison with retaining glycosyltransferases of fold family GT-B reveals a putative active centre of trehalose phosphorylase, and results of site-directed mutagenesis confirm the predicted crucial role of Asp379, His403, Arg507 and Lys512 in catalysis and also delineate a function of these residues in determining the large preference of the wild-type enzyme for the phosphorolysis compared with hydrolysis of alpha,alpha-trehalose. The pseudo-disaccharide validoxylamine A was identified as a strong inhibitor of trehalose phosphorylase (K(i)=1.7+/-0.2 microM) that displays 350-fold tighter binding to the enzyme-phosphate complex than the non-phosphorolysable substrate analogue alpha,alpha-thio-trehalose. Structural and electronic features of the inhibitor that may be responsible for high-affinity binding and their complementarity to an anticipated glucosyl oxocarbenium ion-like transition state are discussed.
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Affiliation(s)
- Christiane Goedl
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
| | - Richard Griessler
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
| | - Alexandra Schwarz
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, Petersgasse 12, A-8010 Graz, Austria
- To whom correspondence should be addressed (email )
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38
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Hang HC, Bertozzi CR. The chemistry and biology of mucin-type O-linked glycosylation. Bioorg Med Chem 2005; 13:5021-34. [PMID: 16005634 DOI: 10.1016/j.bmc.2005.04.085] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 04/26/2005] [Indexed: 02/04/2023]
Abstract
Mucin-type O-linked glycosylation is a fundamental post-translational modification that is involved in a variety of important biological processes. However, the lack of chemical tools to study mucin-type O-linked glycosylation has hindered our molecular understanding of O-linked glycans in many biological contexts. The review discusses the significance of mucin-type O-linked glycosylation initiated by the polypeptide N-acetylgalactosaminyltransferases in biology and development of chemical tools to study these enzymes and their substrates.
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Affiliation(s)
- Howard C Hang
- Department of Chemistry, University of California, Berkeley 94720-1460, USA.
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39
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Larivière L, Sommer N, Moréra S. Structural evidence of a passive base-flipping mechanism for AGT, an unusual GT-B glycosyltransferase. J Mol Biol 2005; 352:139-50. [PMID: 16081100 DOI: 10.1016/j.jmb.2005.07.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 07/01/2005] [Accepted: 07/04/2005] [Indexed: 01/17/2023]
Abstract
The Escherichia coli T4 bacteriophage uses two glycosyltransferases to glucosylate and thus protect its DNA: the retaining alpha-glucosyltransferase (AGT) and the inverting beta-glucosyltransferase (BGT). They glucosylate 5-hydroxymethyl cytosine (5-HMC) bases of duplex DNA using UDP-glucose as the sugar donor to form an alpha-glucosidic linkage and a beta-glucosidic linkage, respectively. Five structures of AGT have been determined: a binary complex with the UDP product and four ternary complexes with UDP or UDP-glucose and oligonucleotides containing an A:G, HMU:G (hydroxymethyl uracyl) or AP:G (apurinic/apyrimidinic) mismatch at the target base-pair. AGT adopts the GT-B fold, one of the two folds known for GTs. However, while the sugar donor binding mode is classical for a GT-B enzyme, the sugar acceptor binding mode is unexpected and breaks the established consensus: AGT is the first GT-B enzyme that predominantly binds both the sugar donor and acceptor to the C-terminal domain. Its active site pocket is highly similar to four retaining GT-B glycosyltransferases (trehalose-6-phosphate synthase, glycogen synthase, glycogen and maltodextrin phosphorylases) strongly suggesting a common evolutionary origin and catalytic mechanism for these enzymes. Structure-guided mutagenesis and kinetic analysis do not permit identification of a nucleophile residue responsible for a glycosyl-enzyme intermediate for the classical double displacement mechanism. Interestingly, the DNA structures reveal partially flipped-out bases. They provide evidence for a passive role of AGT in the base-flipping mechanism and for its specific recognition of the acceptor base.
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Affiliation(s)
- Laurent Larivière
- Laboratoire d'Enzymologie et Biochimie Structurales, UPR 9063 CNRS, Bât.34, 91198-Gif-sur-Yvette, France
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40
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Ercan A, West CM. Kinetic analysis of a Golgi UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-alpha-glucosaminyltransferase from Dictyostelium. Glycobiology 2005; 15:489-500. [PMID: 15616122 DOI: 10.1093/glycob/cwi034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mucin-type O-glycosylation in Dictyostelium is initiated in the Golgi by a UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-alpha-glucosaminyltransferase (Dd-pp alphaGlcNAcT2) whose sequence is distantly related to the sequences of animal polypeptide-Thr/Ser N-acetyl-alpha-galactosaminyltransferases, such as murine Mm-pp alphaGalNAcT1. To evaluate the significance of this similarity, highly purified Dd-pp alphaGlcNAcT2 was assayed using synthetic peptides derived from known substrates. Dd-pp alphaGlcNAcT2 strongly prefers UDP-GlcNAc over UDP-GalNAc, preferentially modifies the central region of the peptide, and modifies Ser in addition to Thr residues. Initial velocity measurements performed over a matrix of UDP-GlcNAc donor and peptide acceptor concentrations indicate that the substrates bind to the enzyme in ordered fashion before the chemical conversion. Substrate inhibition exerted by a second peptide, and the pattern of product inhibition exerted by UDP, suggest that UDP-GlcNAc binds first and the peptide binds second, consistent with data reported for Mm-pp alphaGalNAcT1. Two selective competitive inhibitors of Mm-pp alphaGalNAcT1, retrieved from a screen of neutral-charge uridine derivatives, also inhibit Dd-pp alphaGlcNAcT1 competitively with only slightly less efficacy. Inhibition is specific for Dd-pp alphaGlcNAcT2 relative to two other Dictyostelium retaining glycosyltransferases. These data support a phylogenetic model in which the alphaGlcNAcT function in unicellular eukaryotes converted to an alphaGalNAcT function in the metazoan ortholog while conserving a similar reaction mechanism and active site architecture.
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Affiliation(s)
- Altan Ercan
- Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 937, Oklahoma City, OK 73104, USA
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41
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Neubacher B, Schmidt D, Ziegelmuller P, Thiem J. Preparation of sialylated oligosaccharides employing recombinant trans-sialidase from Trypanosoma cruzi. Org Biomol Chem 2005; 3:1551-6. [PMID: 15827656 DOI: 10.1039/b500042d] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Terminally sialylated oligosaccharides were synthesised employing recombinant trans-sialidase from Trypanosoma cruzi. Regio- and stereoselectively Sia-alpha(2-3)-Gal-betaR derivatives could be obtained in respectable yields, using combined chemical and enzymatic methodologies. An array of different disaccharide precursors such as Gal-beta(1-3)-GalNAc-alphaSer/Thr, lactosides and lactosamide derivatives were sialylated and successfully purified by facile isolation procedures. Depending on the acceptor structure isolated, yields for trans-sialylation products were between 20 and 60%.
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Affiliation(s)
- Bjorn Neubacher
- Institute of Organic Chemistry, University of Hamburg, Germany
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42
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Watts AG, Withers SG. The synthesis of some mechanistic probes for sialic acid processing enzymes and the labeling of a sialidase from Trypanosoma rangeli. CAN J CHEM 2004. [DOI: 10.1139/v04-125] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sialyl hydrolases, trans-sialidases, and sialyl transferases are biologically important enzymes that are responsible for the incorporation and removal of sialic acid residues, which decorate many cell surface glycocongugates. Two fluorinated sialic acid derivatives have been synthesized as mechanism-based inactivators, to probe the catalytic mechanisms through which sialidases and trans-sialidases operate. Both compounds are known to be covalent inactivators of a trans-sialidase from Trypanosoma cruzi. Here, 3-fluorosialosyl fluoride has been found to covalently label the catalytic nucleophile of a sialidase from T. rangeli, and the residue involved is shown to be Tyr346 within the sequence DENSGYSSVL. This is the first demonstration that sialidases operate through a covalent glycosyl-enzyme intermediate, strongly suggesting a common catalytic mechanism amongst all members of the sialidase superfamily. CMP-3-fluoro sialic acid is a competitive inhibitor of sialyl transferases and was synthesized via a two-step enzymatic process from commercially available N-acetyl mannosamine, 3-fluoropyruvic acid, and cytidine triphosphate in around 84% yield.Key words: sialidase, mechanism, labeling, nucleophile, inhibitor.
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43
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Tvaroska I. Molecular modeling insights into the catalytic mechanism of the retaining galactosyltransferase LgtC. Carbohydr Res 2004; 339:1007-14. [PMID: 15010308 DOI: 10.1016/j.carres.2003.11.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Accepted: 11/17/2003] [Indexed: 11/24/2022]
Abstract
The bacterial enzyme lipopolysaccharyl alpha-galactosyltransferase C (EC 2.4.1.x, LgtC) is involved in the synthesis of lipooligosaccharides displayed on the cell surfaces of Neisseria meningitidis. LgtC catalyzes the transfer of a galactosyl residue from UDP-Gal to the terminal galactose residue of glycoconjugates with an overall retention of stereochemistry at the anomeric center. Several hypothetical catalytic mechanisms of the LgtC enzyme were examined herein using DFT quantum chemical methods up to the B3LYP/6-311++G**//B3LYP/6-31G* level. The computational model used to follow the reaction is based on the crystallographic structure of LgtC in complex with both the nucleotide-galactose donor and the oligosaccharide-acceptor analogues. The 136 atoms included in this model represent fragments of residues critical for the substrate binding and catalysis. From our calculations, the preferred pathway is predicted to be a one step mechanism with the nucleophilic attack of the acceptor oxygen onto the anomeric carbon and the proton transfer to a phosphate oxygen occurring simultaneously. This mechanism has an A(N)D(N)A(H)D(H) character, with the unique transition state structure in which the attacking galactose group is more closely bound to the anomeric carbon than to the UDP leaving group and where the hydrogen bond between the nucleophile and the leaving group oxygens facilitates the attack of the acceptor O4(') from the same side of the transferred galactose.
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Affiliation(s)
- Igor Tvaroska
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava 845-38, Slovak Republic.
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44
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Snajdrová L, Kulhánek P, Imberty A, Koca J. Molecular dynamics simulations of glycosyltransferase LgtC. Carbohydr Res 2004; 339:995-1006. [PMID: 15010307 DOI: 10.1016/j.carres.2003.12.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Accepted: 12/17/2003] [Indexed: 11/26/2022]
Abstract
Molecular dynamics simulations have been performed on fully solvated alpha-(1-->4)-galactosyltransferase LgtC from Neisseria meningitidis with and without the donor substrate UDP-Gal and in the presence of the manganese ion. The analysis of the trajectories revealed a limited movement in the loop X (residues 75-80) and a larger conformational change in the loop Y (residues 246-251) in the simulation, when UDP-Gal was not present. In this case, the loops X and Y open by almost 10A, exposing the active site to the solvent. The 'hinge region' responsible for the opening is composed of residues 246-247. We have also analyzed the behavior of the manganese ion in the simulations. The coordination number is 6 when UDP-Gal is present and it increases to 7 when it is absent. In the latter case, three water molecules become coordinated to the ion. In both cases, the coordination is very stable implying that the manganese ion is tightly bound in the active site of the enzyme even if UDP-Gal is not present. Further analysis of the structural water molecules location confirmed that the mobility of water molecules in the active site and the accessibility of this site for solvent are higher in the absence of the substrate.
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Affiliation(s)
- Lenka Snajdrová
- Centre de Recherches sur les Macromolécules Végétales, CNRS and Université Joseph Fourier, IFR 2607, BP 53, F-38041 Grenoble, France
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45
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Gibson RP, Tarling CA, Roberts S, Withers SG, Davies GJ. The donor subsite of trehalose-6-phosphate synthase: binary complexes with UDP-glucose and UDP-2-deoxy-2-fluoro-glucose at 2 A resolution. J Biol Chem 2003; 279:1950-5. [PMID: 14570926 DOI: 10.1074/jbc.m307643200] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trehalose is an unusual non-reducing disaccharide that plays a variety of biological roles, from food storage to cellular protection from environmental stresses such as desiccation, pressure, heat-shock, extreme cold, and oxygen radicals. It is also an integral component of the cell-wall glycolipids of mycobacteria. The primary enzymatic route to trehalose first involves the transfer of glucose from a UDP-glucose donor to glucose-6-phosphate to form alpha,alpha-1,1 trehalose-6-phosphate. This reaction, in which the configurations of two glycosidic bonds are set simultaneously, is catalyzed by the glycosyltransferase trehalose-6-phosphate synthase (OtsA), which acts with retention of the anomeric configuration of the UDP-sugar donor. The classification of activated sugar-dependent glycosyltransferases into approximately 70 distinct families based upon amino acid sequence similarities places OtsA in glycosyltransferase family 20 (see afmb.cnrs-mrs.fr/CAZY/). The recent 2.4 A structure of Escherichia coli OtsA revealed a two-domain enzyme with catalysis occurring at the interface of the twin beta/alpha/beta domains. Here we present the 2.0 A structures of the E. coli OtsA in complex with either UDP-Glc or the non-transferable analogue UDP-2-deoxy-2-fluoroglucose. Both complexes unveil the donor subsite interactions, confirming a strong similarity to glycogen phosphorylases, and reveal substantial conformational differences to the previously reported complex with UDP and glucose 6-phosphate. Both the relative orientation of the two domains and substantial (up to 10 A) movements of an N-terminal loop (residues 9-22) characterize the more open "relaxed" conformation of the binary UDP-sugar complexes reported here.
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Affiliation(s)
- Robert P Gibson
- Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, United Kingdom
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46
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André I, Tvaroska I, Carver JP. On the reaction pathways and determination of transition-state structures for retaining alpha-galactosyltransferases. Carbohydr Res 2003; 338:865-77. [PMID: 12681911 DOI: 10.1016/s0008-6215(03)00050-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The catalytic mechanism of retaining glycosyltransferases is not yet completely understood, but one possible mechanism, by analogy with retaining glycosidases, is a double-displacement mechanism via a covalent glycosyl-enzyme intermediate (CGE). We have investigated various reaction pathways for this mechanism using non-empirical quantum mechanical methods. Because a double-displacement mechanism presumes a reaction happening in two steps, we have used predefined reaction coordinates to calculate the potential energy surface describing each step of the mechanism. By investigating several potential candidates to act as a catalytic base, this study attempts to shed some light on the unclear mechanism of the second step of the reaction. All intermediates and transition states on the reaction pathways were characterized using basis sets up to the DFT/B3LYP/6-311++G**//DFT/B3LYP/6-31G* level. Reaction pathways and structural changes were compared with the results previously obtained for inverting glycosyltransferases. The outcome of this study indicates, that among the reaction models investigated, the energetically favorable one is also the most plausible given the existing experimental data. This model requires the presence of only one catalytic acid in the active site with the UDP functioning as a general base in the second step of the reaction. This mechanism is in agreement with both kinetic data in the literature and the description of X-ray structures of retaining glycosyltransferases solved up to today.
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Affiliation(s)
- Isabelle André
- GlycoDesign Inc., 480 University Avenue, Suite 900, Toronto, ON, Canada M5G 1V2.
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47
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Kaniuk NA, Monteiro MA, Parker CT, Whitfield C. Molecular diversity of the genetic loci responsible for lipopolysaccharide core oligosaccharide assembly within the genus Salmonella. Mol Microbiol 2002; 46:1305-18. [PMID: 12453217 DOI: 10.1046/j.1365-2958.2002.03243.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The waa locus on the chromosome of Salmonella enterica encodes enzymes involved in the assembly of the core oligosaccharide region of the lipopolysaccharide (LPS) molecule. To date, there are two known core structures in Salmonella, represented by serovars Typhimurium (subspecies I) and Arizonae (subspecies IIIA). The waa locus for serovar Typhimurium has been characterized. Here, the corresponding locus from serovar Arizonae is described, and the molecular basis for the distinctive structures is established. Eleven of the 13 open reading frames (ORFs) are shared by the two loci and encode conserved proteins of known function. Two polymorphic regions distinguish the waa loci. One involves the waaK gene, the product of which adds a terminal alpha-1,2-linked N-acetylglucosamine residue that characterizes the serovar Typhimurium core oligosaccharide. There is an extensive internal deletion within waaK of serovar Arizonae. The serovar Arizonae locus contains a novel ORF (waaH) between the waaB and waaP genes. Structural analyses and in vitro glycosyltransferase assays identified WaaH as the UDP-glucose:(glucosyl) LPS alpha-1,2-glucosyltransferase responsible for the addition of the characteristic terminal glucose residue found in serovar Arizonae. Isolates comprising the Salmonella Reference Collections, SARC (representing the eight subspecies of S. enterica) and SARB (representing subspecies I), were examined to assess the distribution of the waa locus polymorphic regions in natural populations. These comparative studies identified additional waa locus polymorphisms, shedding light on the genetic basis for diversity in the LPS core oligosaccharides of Salmonella isolates and identifying potential sources of further novel LPS structures.
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Affiliation(s)
- Natalia A Kaniuk
- Department of Microbiology, University of Guelph, Guelph, ON, Canada, N1G 2W1
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Abstract
OtsA is required for the biosynthesis of trehalose, a nonreducing disaccharide that is important for bacterial survival and stress responses. In this issue of Chemistry & Biology, the structure of OtsA is uncovered and reveals an unexpected relationship between the enzyme's structure and function.
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Affiliation(s)
- Stephen G Withers
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, Canada BC V6T 1Z1
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