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Hunter CD, Guo T, Daskhan G, Richards MR, Cairo CW. Synthetic Strategies for Modified Glycosphingolipids and Their Design as Probes. Chem Rev 2018; 118:8188-8241. [DOI: 10.1021/acs.chemrev.8b00070] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Carmanah D. Hunter
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Tianlin Guo
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Gour Daskhan
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Michele R. Richards
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Christopher W. Cairo
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
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2
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Bevan JGM, Lourenço EC, Chaves-Ferreira M, Rodrigues JA, Rita Ventura M. Immobilization of UDP-Galactose on an Amphiphilic Resin. European J Org Chem 2018. [DOI: 10.1002/ejoc.201701620] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jessica G. M. Bevan
- Biology of Parasitism Laboratory; Instituto de Medicina Molecular; Faculdade de Medicina da Universidade de Lisboa; Avenida Professor Egas Moniz 1649-028 Lisboa Portugal
- Bioorganic Chemistry Laboratory; Instituto de Tecnologia Química e Biológica; Universidade Nova de Lisboa; Apartado 127 2780-901 Oeiras Portugal
| | - Eva C. Lourenço
- Bioorganic Chemistry Laboratory; Instituto de Tecnologia Química e Biológica; Universidade Nova de Lisboa; Apartado 127 2780-901 Oeiras Portugal
| | - Miguel Chaves-Ferreira
- Biology of Parasitism Laboratory; Instituto de Medicina Molecular; Faculdade de Medicina da Universidade de Lisboa; Avenida Professor Egas Moniz 1649-028 Lisboa Portugal
| | - João A. Rodrigues
- Biology of Parasitism Laboratory; Instituto de Medicina Molecular; Faculdade de Medicina da Universidade de Lisboa; Avenida Professor Egas Moniz 1649-028 Lisboa Portugal
| | - M. Rita Ventura
- Bioorganic Chemistry Laboratory; Instituto de Tecnologia Química e Biológica; Universidade Nova de Lisboa; Apartado 127 2780-901 Oeiras Portugal
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3
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An efficient method for the preparation of 1,5-anhydroalditol from unprotected carbohydrates via glycopyranosyl iodide. Tetrahedron Lett 2016. [DOI: 10.1016/j.tetlet.2016.10.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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4
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Miyagawa A, Takeuchi S, Itoda S, Toyama S, Kurimoto K, Yamamura H, Ito Y. Chemical synthesis and isolation of UDP-2-deoxy glucose and galactose. SYNTHETIC COMMUN 2016. [DOI: 10.1080/00397911.2016.1227849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Atsushi Miyagawa
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Shunya Takeuchi
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Shinji Itoda
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Sanami Toyama
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Kenta Kurimoto
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Hatsuo Yamamura
- Department of Materials Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, Aichi, Japan
| | - Yukishige Ito
- Synthetic Cellular Chemistry Laboratory, Riken, 2-1 Hirosawa, Wako, Saitama, Japan
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5
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Sun Q, Li X, Sun J, Gong S, Liu G, Liu G. An improved P(V)-N activation strategy for the synthesis of nucleoside diphosphate 6-deoxy-l-sugars. Tetrahedron 2014. [DOI: 10.1016/j.tet.2013.11.059] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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6
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Wang S, Cuesta-Seijo JA, Lafont D, Palcic MM, Vidal S. Design of glycosyltransferase inhibitors: pyridine as a pyrophosphate surrogate. Chemistry 2013; 19:15346-57. [PMID: 24108680 DOI: 10.1002/chem.201301871] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/25/2013] [Indexed: 12/12/2022]
Abstract
A series of ten glycosyltransferase inhibitors has been designed and synthesized by using pyridine as a pyrophosphate surrogate. The series was prepared by conjugation of carbohydrate, pyridine, and nucleoside building blocks by using a combination of glycosylation, the Staudinger-Vilarrasa amide-bond formation, and azide-alkyne click chemistry. The compounds were evaluated as inhibitors of five metal-dependent galactosyltransferases. Crystallographic analyses of three inhibitors complexed in the active site of one of the enzymes confirmed that the pyridine moiety chelates the Mn(2+) ion causing a slight displacement (2 Å) from its original position. The carbohydrate head group occupies a different position than in the natural uridine diphosphate (UDP)-Gal substrate with little interaction with the enzyme.
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Affiliation(s)
- Shuai Wang
- Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, Laboratoire de Chimie Organique 2, Glycochimie, UMR 5246, CNRS and Université Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 6922 Villeurbanne (France), Fax: (+33) 472-448-109
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7
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Sugiarto G, Lau K, Qu J, Li Y, Lim S, Mu S, Ames JB, Fisher AJ, Chen X. A sialyltransferase mutant with decreased donor hydrolysis and reduced sialidase activities for directly sialylating LewisX. ACS Chem Biol 2012; 7:1232-40. [PMID: 22583967 DOI: 10.1021/cb300125k] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glycosyltransferases are important catalysts for enzymatic and chemoenzymatic synthesis of complex carbohydrates and glycoconjugates. The glycosylation efficiencies of wild-type glycosyltransferases vary considerably when different acceptor substrates are used. Using a multifunctional Pasteurella multocida sialyltransferase 1 (PmST1) as an example, we show here that the sugar nucleotide donor hydrolysis activity of glycosyltransferases contributes significantly to the low yield of glycosylation when a poor acceptor substrate is used. With a protein crystal structure-based rational design, we generated a single mutant (PmST1 M144D) with decreased donor hydrolysis activity without significantly affecting its α2-3-sialylation activity when a poor fucose-containing acceptor substrate was used. The single mutant also has a drastically decreased α2-3-sialidase activity. X-ray and NMR structural studies revealed that unlike the wild-type PmST1, which changes to a closed conformation once a donor binds, the M144D mutant structure adopts an open conformation even in the presence of the donor substrate. The PmST1 M144D mutant with decreased donor hydrolysis and reduced sialidase activity has been used as a powerful catalyst for efficient chemoenzymatic synthesis of complex sialyl Lewis(x) antigens containing different sialic acid forms. This work sheds new light on the effect of donor hydrolysis activity of glycosyltransferases on glycosyltransferase-catalyzed reactions and provides a novel strategy to improve glycosyltransferase substrate promiscuity by decreasing its donor hydrolysis activity.
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Affiliation(s)
- Go Sugiarto
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Kam Lau
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Jingyao Qu
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Yanhong Li
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Sunghyuk Lim
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Shengmao Mu
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - James B. Ames
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Andrew J. Fisher
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
| | - Xi Chen
- Department
of Chemistry and ‡Department of Molecular and Cellular Biology, University of California-Davis, One Shields Avenue,
Davis, California 95616, United States
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8
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Jørgensen R, Grimm LL, Sindhuwinata N, Peters T, Palcic MM. A glycosyltransferase inhibitor from a molecular fragment library simultaneously interferes with metal ion and substrate binding. Angew Chem Int Ed Engl 2012; 51:4171-5. [PMID: 22407594 DOI: 10.1002/anie.201108345] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Indexed: 12/13/2022]
Affiliation(s)
- Rene Jørgensen
- Carlsberg Laboratory, Gamle Carlsberg Vej 10, 1799 Copenhagen V, Denmark
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9
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Jørgensen R, Grimm LL, Sindhuwinata N, Peters T, Palcic MM. A Glycosyltransferase Inhibitor from a Molecular Fragment Library Simultaneously Interferes with Metal Ion and Substrate Binding. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108345] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Descroix K, Pesnot T, Yoshimura Y, Gehrke SS, Wakarchuk W, Palcic MM, Wagner GK. Inhibition of galactosyltransferases by a novel class of donor analogues. J Med Chem 2012; 55:2015-24. [PMID: 22356319 DOI: 10.1021/jm201154p] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Galactosyltransferases (GalT) are important molecular targets in a range of therapeutic areas, including infection, inflammation, and cancer. GalT inhibitors are therefore sought after as potential lead compounds for drug discovery. We have recently discovered a new class of GalT inhibitors with a novel mode of action. In this publication, we describe a series of analogues which provide insights, for the first time, into SAR for this new mode of GalT inhibition. We also report that a new C-glycoside, designed as a chemically stable analogue of the most potent inhibitor in this series, retains inhibitory activity against a panel of GalTs. Initial results from cellular studies suggest that despite their polarity, these sugar-nucleotides are taken up by HL-60 cells. Results from molecular modeling studies with a representative bacterial GalT provide a rationale for the differences in bioactivity observed in this series. These findings may provide a blueprint for the rational development of new GalT inhibitors with improved potency.
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Affiliation(s)
- Karine Descroix
- School of Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
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11
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Pesnot T, Palcic MM, Wagner GK. A novel fluorescent probe for retaining galactosyltransferases. Chembiochem 2010; 11:1392-8. [PMID: 20533489 DOI: 10.1002/cbic.201000013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Glycosyltransferases (GTs) are a large class of carbohydrate-active enzymes that are involved, in both pro- and eukaryotic organisms, in numerous important biological processes, from cellular adhesion to carcinogenesis. GTs have enormous potential as molecular targets for chemical biology and drug discovery. For the full realisation of this potential, operationally simple and generally applicable GT bioassays, especially for inhibitor screening, are indispensable tools. In order to facilitate the development of GT high-throughput screening assays for the identification of GT inhibitors, we have developed novel, fluorescent derivatives of UDP-galactose (UDP-Gal) that are recognised as donor analogues by several different retaining galactosyltransferases (GalTs). We demonstrate for one of these derivatives that fluorescence emission is quenched upon specific binding to individual GalTs, and that this effect can be used as the read-out in ligand-displacement experiments. The novel fluorophore acts as an excellent sensor for several different enzymes and is suitable for the development of a new type of GalT bioassay, whose modular nature and operational simplicity will significantly facilitate inhibitor screening. Importantly, the structural differences between the natural donor UDP-Gal and the new fluorescent derivatives are minimal, and the general assay principle described herein may therefore also be applicable to other GalTs and/or proteins that use nucleotides or nucleotide conjugates as their cofactor.
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Affiliation(s)
- Thomas Pesnot
- School of Pharmacy, University of East Anglia, Norwich, NR4 7TJ UK
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12
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Smoot JT, Demchenko AV. Oligosaccharide synthesis: from conventional methods to modern expeditious strategies. Adv Carbohydr Chem Biochem 2009; 62:161-250. [PMID: 19501706 DOI: 10.1016/s0065-2318(09)00005-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- James T Smoot
- Department of Chemistry and Biochemistry, University of Missouri, St. Louis, MO 63121, USA
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13
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Tumbale P, Jamaluddin H, Thiyagarajan N, Acharya KR, Brew K. Screening a limited structure-based library identifies UDP-GalNAc-specific mutants of alpha-1,3-galactosyltransferase. Glycobiology 2008; 18:1036-43. [PMID: 18782853 DOI: 10.1093/glycob/cwn083] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Complex glycans have important roles in biological recognition processes and considerable pharmaceutical potential. The synthesis of novel glycans can be facilitated by engineering glycosyltransferases to modify their substrate specificities. The choice of sites to modify requires the knowledge of the structures of enzyme-substrate complexes while the complexity of protein structures necessitates the exploration of a large array of multisite mutations. The retaining glycosyltransferase, alpha-1,3-galactosyltransferase (alpha3GT), which catalyzes the synthesis of the alpha-Gal epitope, has strict specificity for UDP-galactose as a donor substrate. Based on the structure of a complex of UDP-galactose with alpha3GT, the specificity for the galactose moiety can be partly attributed to residues that interact with the galactose 2-OH group, particularly His280 and Ala282. With the goal of engineering a variant of bovine alpha3GT with GalNAc transferase activity, we constructed a limited library of 456 alpha3GT mutants containing 19 alternative amino acids at position 280, two each at 281 and 282 and six at position 283. Clones (1500) were screened by assaying partially purified bacterially expressed variants for GalNAc transferase activity. Mutants with the highest levels of GalNAc transferase activity, AGGL or GGGL, had substitutions at all four sites. The AGGL mutant had slightly superior GalNAc transferase activity amounting to about 3% of the activity of the wild-type enzyme with UDP-Gal. This mutant had a low activity with UDP-Gal; its crystallographic structure suggests that the smaller side chains at residues 280-282 form a pocket to accommodate the larger acetamido group of GalNAc. Mutational studies indicate that Leu283 is important for stability in this mutant.
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Affiliation(s)
- Percy Tumbale
- Department of Biomedical Science, College of Biomedical Science, Florida Atlantic University, Glades Road, Boca Raton, FL 33431, USA
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14
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Tumbale P, Jamaluddin H, Thiyagarajan N, Brew K, Acharya KR. Structural basis of UDP-galactose binding by alpha-1,3-galactosyltransferase (alpha3GT): role of negative charge on aspartic acid 316 in structure and activity. Biochemistry 2008; 47:8711-8. [PMID: 18651752 DOI: 10.1021/bi800852a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
alpha-1,3-Galactosyltransferase (alpha3GT) catalyzes the transfer of galactose from UDP-galactose to form an alpha 1-3 link with beta-linked galactosides; it is part of a family of homologous retaining glycosyltransferases that includes the histo-blood group A and B glycosyltransferases, Forssman glycolipid synthase, iGb3 synthase, and some uncharacterized prokaryotic glycosyltransferases. In mammals, the presence or absence of active forms of these enzymes results in antigenic differences between individuals and species that modulate the interplay between the immune system and pathogens. The catalytic mechanism of alpha3GT is controversial, but the structure of an enzyme complex with the donor substrate could illuminate both this and the basis of donor substrate specificity. We report here the structure of the complex of a low-activity mutant alpha3GT with UDP-galactose (UDP-gal) exhibiting a bent configuration stabilized by interactions of the galactose with multiple residues in the enzyme including those in a highly conserved region (His315 to Ser318). Analysis of the properties of mutants containing substitutions for these residues shows that catalytic activity is strongly affected by His315 and Asp316. The negative charge of Asp316 is crucial for catalytic activity, and structural studies of two mutants show that its interaction with Arg202 is needed for an active site structure that facilitates the binding of UDP-gal in a catalytically competent conformation.
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Affiliation(s)
- Percy Tumbale
- Department of Biomedical Science, Florida Atlantic University, 777 Glades Road, Boca Raton, Florida 33431, USA
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15
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Bosco M, Gall SL, Rihouey C, Couve-Bonnaire S, Bardor M, Lerouge P, Pannecoucke X. 6-Azido d-galactose transfer to N-acetyl-d-glucosamine derivative using commercially available β-1,4-galactosyltransferase. Tetrahedron Lett 2008. [DOI: 10.1016/j.tetlet.2008.02.018] [Citation(s) in RCA: 10] [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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16
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Danac R, Ball L, Gurr SJ, Fairbanks AJ. Synthesis of UDP-glucose derivatives modified at the 3-OH as potential chain terminators of beta-glucan biosynthesis. Carbohydr Res 2008; 343:1012-22. [PMID: 18336802 DOI: 10.1016/j.carres.2008.01.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 01/17/2008] [Accepted: 01/22/2008] [Indexed: 01/07/2023]
Abstract
A series of UDP-D-glucose derivatives and precursors that have been modified at C-3 were synthesised from D-glucose as potential chain terminators of beta-glucan biosynthesis. None of the UDP-derivatives or the precursors tested displayed significant anti-fungal activity in a series of germination assays on the dermatophyte Trichophyton rubrum.
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Affiliation(s)
- Ramona Danac
- Chemistry Research Laboratory, Department of Plant Sciences, Oxford University, Mansfield Road, Oxford OX1 3TA, UK
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17
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Alfaro JA, Zheng RB, Persson M, Letts JA, Polakowski R, Bai Y, Borisova SN, Seto NOL, Lowary TL, Palcic MM, Evans SV. ABO(H) blood group A and B glycosyltransferases recognize substrate via specific conformational changes. J Biol Chem 2008; 283:10097-108. [PMID: 18192272 DOI: 10.1074/jbc.m708669200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The final step in the enzymatic synthesis of the ABO(H) blood group A and B antigens is catalyzed by two closely related glycosyltransferases, an alpha-(1-->3)-N-acetylgalactosaminyltransferase (GTA) and an alpha-(1-->3)-galactosyltransferase (GTB). Of their 354 amino acid residues, GTA and GTB differ by only four "critical" residues. High resolution structures for GTB and the GTA/GTB chimeric enzymes GTB/G176R and GTB/G176R/G235S bound to a panel of donor and acceptor analog substrates reveal "open," "semi-closed," and "closed" conformations as the enzymes go from the unliganded to the liganded states. In the open form the internal polypeptide loop (amino acid residues 177-195) adjacent to the active site in the unliganded or H antigen-bound enzymes is composed of two alpha-helices spanning Arg(180)-Met(186) and Arg(188)-Asp(194), respectively. The semi-closed and closed forms of the enzymes are generated by binding of UDP or of UDP and H antigen analogs, respectively, and show that these helices merge to form a single distorted helical structure with alternating alpha-3(10)-alpha character that partially occludes the active site. The closed form is distinguished from the semi-closed form by the ordering of the final nine C-terminal residues through the formation of hydrogen bonds to both UDP and H antigen analogs. The semi-closed forms for various mutants generally show significantly more disorder than the open forms, whereas the closed forms display little or no disorder depending strongly on the identity of residue 176. Finally, the use of synthetic analogs reveals how H antigen acceptor binding can be critical in stabilizing the closed conformation. These structures demonstrate a delicately balanced substrate recognition mechanism and give insight on critical aspects of donor and acceptor specificity, on the order of substrate binding, and on the requirements for catalysis.
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Affiliation(s)
- Javier A Alfaro
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
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18
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Brockhausen I, Larsson EA, Hindsgaul O. A very simple synthesis of GlcNAc-α-pyrophosphoryl-decanol: A substrate for the assay of a bacterial galactosyltransferase. Bioorg Med Chem Lett 2008; 18:804-7. [DOI: 10.1016/j.bmcl.2007.11.031] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Revised: 11/07/2007] [Accepted: 11/09/2007] [Indexed: 11/17/2022]
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19
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Angulo J, Langpap B, Blume A, Biet T, Meyer B, Krishna NR, Peters H, Palcic MM, Peters T. Blood group B galactosyltransferase: insights into substrate binding from NMR experiments. J Am Chem Soc 2007; 128:13529-38. [PMID: 17031966 DOI: 10.1021/ja063550r] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biosynthesis of human blood group B antigens is accomplished by a highly specific galactosyltransferase (GTB). On the basis of NMR experiments, we propose a "molecular tweezers mechanism" that accounts for the exquisite stereoselectivity of donor substrate selection. Transferred NOE experiments for the first time reveal the bioactive conformation of the donor substrate UDP-galactose (UDP-Gal) and of its enzymatically inactive analogue, UDP-glucose (UDP-Glc). Both bind to GTB in a folded conformation that is sparsely populated in solution, whereas acceptor ligands bind in a conformation that predominates in solution. The bound conformations of UDP-Gal and UDP-Glc are identical within experimental error. Therefore, GTB must discriminate between the two activated sugars on the basis of a hitherto unknown transition state that can only be formed in the case of UDP-Gal. A full relaxation and exchange matrix analysis of STD NMR experiments reveals that acceptor substrates dissociate significantly faster (k(off) > 100 Hz) from the binding pocket than donor substrates (k(off) approximately 10 Hz). STD NMR experiments also directly show that proper recognition of the hexopyranose rings of the UDP sugars requires bivalent metal cations. At the same time, this analysis furnishes the complete three-dimensional structure of the enzyme with its bound donor substrate UDP-Gal on the basis of a prior crystal structure analysis. We propose that, upon acceptor binding, GTB uses the Asp 302 and Glu 303 side chains as "molecular tweezers" to promote bound UDP-Gal but not UDP-Glc into a transition state that leads to product formation.
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Affiliation(s)
- Jesus Angulo
- Institute of Chemistry, University of Luebeck, Ratzeburger Allee 160, 23538 Luebeck, Germany
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20
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Danac R, Ball L, Gurr SJ, Muller T, Fairbanks AJ. Carbohydrate Chain Terminators: Rational Design of Novel Carbohydrate-Based Antifungal Agents. Chembiochem 2007; 8:1241-5. [PMID: 17583547 DOI: 10.1002/cbic.200700234] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ramona Danac
- Chemistry Research Laboratory, Oxford University, Mansfield Road, Oxford, OX1 3TA, UK
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21
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Muller T, Danac R, Ball L, Gurr SJ, Fairbanks AJ. Synthesis of UDP-GlcNAc derivatives modified at OH-4 as potential chain-terminators of chitin biosynthesis. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.tetasy.2007.05.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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22
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Schweizer F. Synthesis of fluorescently labelled and internally quenched UDP-Gal probes. Carbohydr Res 2007; 342:1831-40. [PMID: 17475229 DOI: 10.1016/j.carres.2007.03.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 03/27/2007] [Accepted: 03/31/2007] [Indexed: 10/23/2022]
Abstract
The preparation of fluorescently labelled and internally quenched UDP-Gal probes bearing a fluorescence emitter and a quencher is described. The rate of transfer using several galactosyltransferases was examined. Our results demonstrate that galactose-modified, sugar-nucleotide-modified and double modified UDP-Gal analogues are recognized as weak substrates by blood group B alpha-(1-->3) galactosyltransferase, alpha-(1-->3) galactosyltransferase and milk bovine beta-(1-->4) galactosyltransferase.
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Affiliation(s)
- Frank Schweizer
- Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2.
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23
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Qian X, Sujino K, Palcic MM, Ratcliffe RM. GLYCOSYLTRANSFERASES IN OLIGOSACCHARIDE SYNTHESIS. J Carbohydr Chem 2007. [DOI: 10.1081/car-120016492] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Saura-Valls M, Fauré R, Ragàs S, Piens K, Brumer H, Teeri T, Cottaz S, Driguez H, Planas A. Kinetic analysis using low-molecular mass xyloglucan oligosaccharides defines the catalytic mechanism of a Populus xyloglucan endotransglycosylase. Biochem J 2006; 395:99-106. [PMID: 16356166 PMCID: PMC1409682 DOI: 10.1042/bj20051396] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Plant XETs [XG (xyloglucan) endotransglycosylases] catalyse the transglycosylation from a XG donor to a XG or low-molecular-mass XG fragment as the acceptor, and are thought to be important enzymes in the formation and remodelling of the cellulose-XG three-dimensional network in the primary plant cell wall. Current methods to assay XET activity use the XG polysaccharide as the donor substrate, and present limitations for kinetic and mechanistic studies of XET action due to the polymeric and polydisperse nature of the substrate. A novel activity assay based on HPCE (high performance capillary electrophoresis), in conjunction with a defined low-molecular-mass XGO {XG oligosaccharide; (XXXGXXXG, where G=Glcbeta1,4- and X=[Xylalpha1,6]Glcbeta1,4-)} as the glycosyl donor and a heptasaccharide derivatized with ANTS [8-aminonaphthalene-1,3,6-trisulphonic acid; (XXXG-ANTS)] as the acceptor substrate was developed and validated. The recombinant enzyme PttXET16A from Populus tremula x tremuloides (hybrid aspen) was characterized using the donor/acceptor pair indicated above, for which preparative scale syntheses have been optimized. The low-molecular-mass donor underwent a single transglycosylation reaction to the acceptor substrate under initial-rate conditions, with a pH optimum at 5.0 and maximal activity between 30 and 40 degrees C. Kinetic data are best explained by a ping-pong bi-bi mechanism with substrate inhibition by both donor and acceptor. This is the first assay for XETs using a donor substrate other than polymeric XG, enabling quantitative kinetic analysis of different XGO donors for specificity, and subsite mapping studies of XET enzymes.
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Affiliation(s)
- Marc Saura-Valls
- *Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, 08017 Barcelona, Spain
| | - Régis Fauré
- †CERMAV-ICMG-FR-CNRS 2607, 38041 Grenoble Cedex 9, France
| | - Sergi Ragàs
- *Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, 08017 Barcelona, Spain
| | - Kathleen Piens
- ‡School of Biotechnology, Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Harry Brumer
- ‡School of Biotechnology, Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Tuula T. Teeri
- ‡School of Biotechnology, Royal Institute of Technology, 106 91 Stockholm, Sweden
| | - Sylvain Cottaz
- †CERMAV-ICMG-FR-CNRS 2607, 38041 Grenoble Cedex 9, France
| | - Hugues Driguez
- †CERMAV-ICMG-FR-CNRS 2607, 38041 Grenoble Cedex 9, France
| | - Antoni Planas
- *Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, 08017 Barcelona, Spain
- To whom correspondence should be addressed (email )
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25
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Monegal A, Pinyol R, Planas A. Capillary electrophoresis method for the enzymatic assay of galactosyltransferases with postreaction derivatization. Anal Biochem 2005; 346:115-23. [PMID: 16185647 DOI: 10.1016/j.ab.2005.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 08/02/2005] [Accepted: 08/09/2005] [Indexed: 10/25/2022]
Abstract
Glycosyltransferases are key enzymes in glycoconjugate biosynthesis, which make them important targets for biomedical research. Among the different methodologies developed to analyze glycosyltransferase activities, fluorophore-assisted capillary electrophoresis (FACE) emerges as a powerful technique in carbohydrate analysis. Its application to monitor glycosyltransferase activity has been limited to reactions with derivatized sugars as acceptor substrates in which a charged fluorophore/chromophore must be introduced, thus requiring tedious preparative synthesis and purification for each single acceptor substrate. Here we describe a novel and general glycosyltransferase assay based on FACE using underivatized acceptor substrates. Enzyme activity is monitored by a discontinuous assay with postreaction derivatization by reductive amination with 8-aminonaphthalene-1,3,6-trisulfonic acid. The reaction mixture is directly analyzed by HPCE (high-performance capillary electrophoresis) under inverted electroosmotic conditions at pH 2.5 and 30 degrees C. After method validation, it was applied to the kinetic characterization of an alpha-1,3-galactosyltransferase, the enzyme responsible for the biosynthesis of alphaGal epitope involved in the hyperacute rejection in xenotransplantation. The absence of a label on the acceptor during the GT reaction avoids any interference of the label with the enzyme, and the postreaction derivatization does not require any purification step.
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Affiliation(s)
- Ana Monegal
- Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain
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26
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Kamath VP, Yeske RE, Gregson JM, Ratcliffe RM, Fang YR, Palcic MM. Large-scale chemical and chemo-enzymatic synthesis of a spacer-containing Pk-trisaccharide. Carbohydr Res 2004; 339:1141-6. [PMID: 15063203 DOI: 10.1016/j.carres.2003.12.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Accepted: 12/26/2003] [Indexed: 10/26/2022]
Abstract
The Pk-trisaccharide, linked to a solid carrier, is a potential agent for neutralization of shiga-like toxin in the gastrointestinal tract. Two approaches to the multigram-scale synthesis of a linkable Pk-trisaccharide derivative were therefore investigated. A four-step chemical synthesis yielded 8-methoxycarbonyloctyl beta-lactoside in 75% yield from lactose. Further conversion of this derivative through either multistep organic synthesis or one-step enzymatic galactosylation with UDP-galactose and recombinant alpha-1,4-galactosyltransferase gave the Pk-trisaccharide derivative 8-methoxycarbonyloctyl alpha-D-galactopyranosyl-(1-->4)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranoside in 25% and 68% overall yields from commercial lactose, respectively.
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Affiliation(s)
- Vivekanand P Kamath
- Department of Research and Process Development, SYNSORB Biotech Inc., 201, 1204 Kensington Road Calgary, Canada AB T2E 6J7
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27
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Zhang J, Chen X, Shao J, Liu Z, Kowal P, Lu Y, Wang PG. Synthesis of galactose-containing oligosaccharides through superbeads and superbug approaches: substrate recognition along different biosynthetic pathways. Methods Enzymol 2003; 362:106-24. [PMID: 12968360 DOI: 10.1016/s0076-6879(03)01009-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Jianbo Zhang
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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28
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Tsuruta O, Yuasa H, Hashimoto H, Sujino K, Otter A, Li H, Palcic MM. Synthesis of GDP-5-thiosugars and their use as glycosyl donor substrates for glycosyltransferases. J Org Chem 2003; 68:6400-6. [PMID: 12895077 DOI: 10.1021/jo0300035] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two thiopyranoside analogues of GDP-sugars, GDP-5-thio-d-mannose (14) and GDP-5-thio-l-fucose (15), were synthesized. The syntheses included the phosphorylations of tetra-O-acetyl-5-thio-d-mannosyl bromide (4) and tri-O-benzoyl-l-fucosyl bromide (6) with silver dibenzyl phosphate, deprotection of the phosphate groups, and condensation of the deprotected phosphates with GMP-imidazolidate (13) in the presence of MgCl(2). These GDP-sugar analogues were found to be donor substrates for alpha(1,2)mannosyltransferase and alpha(1,3)fucosyltransferase, affording a 5-thiomannose-containing disaccharide (18) and a 5-thiofucose-containing trisaccharide (21), respectively. The conformation of the disaccharide analogue 18 was similar to that of its native counterpart by ROESY. These findings for GDP-5-thiosugars together with previous demonstrations of enzymatic transfer from UDP-5-thiosugars will allow the production of panels of oligosaccharide analogues with hydrolase-resistant properties.
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Affiliation(s)
- Osamu Tsuruta
- Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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29
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Liu Z, Lu Y, Zhang J, Pardee K, Wang PG. P1 Trisaccharide (Galalpha1,4Galbeta1,4GlcNAc) synthesis by enzyme glycosylation reactions using recombinant Escherichia coli. Appl Environ Microbiol 2003; 69:2110-5. [PMID: 12676690 PMCID: PMC154772 DOI: 10.1128/aem.69.4.2110-2115.2003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The frequency of Escherichia coli infection has lead to concerns over pathogenic bacteria in our food supply and a demand for therapeutics. Glycolipids on gut cells serve as receptors for the Shiga-like toxin produced by E. coli. Oligosaccharide moiety analogues of these glycolipids can compete with receptors for the toxin, thus acting as antibacterials. An enzymatic synthesis of the P1 trisaccharide (Galalpha1,4Galbeta1,4GlcNAc), one of the oligosaccharide analogues, was assessed in this study. In the proposed synthetic pathway, UDP-glucose was generated from sucrose with an Anabaena sp. sucrose synthase and then converted with an E. coli UDP-glucose 4-epimerase to UDP-galactose. Two molecules of galactose were linked to N-acetylglucosamine subsequently with a Helicobacter pylori beta-l,4-galactosyltransferase and a Neisseria meningitidis alpha-1,4-galactosyltransferase to produce one molecule of P1 trisaccharide. The four enzymes were coexpressed in a single genetically engineered E. coli strain that was then permeabilized and used to catalyze the enzymatic reaction. P1 trisaccharide was accumulated up to 50 mM (5.4 g in a 200-ml reaction volume), with a 67% yield based on the consumption of N-acetylglucosamine. This study provides an efficient approach for the preparative-scale synthesis of P1 trisaccharide with recombinant bacteria.
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Affiliation(s)
- Ziye Liu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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30
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Xia J, Alderfer JL, Srikrishnan T, Chandrasekaran EV, Matta KL. A convergent synthesis of core 2 branched sialylated and sulfated oligosaccharides. Bioorg Med Chem 2002; 10:3673-84. [PMID: 12213483 DOI: 10.1016/s0968-0896(02)00246-8] [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: 10/27/2022]
Abstract
A convergent pathway for the syntheses of core 2 oligosaccharide analogues 1 and 2, and a natural form sialylated and sulfated hexasaccharide 3 was developed. Construction of pentasaccharides 24, 27 and hexasaccharide 28 was achieved by complete regioselective glycosylation of the 6-OH in the acceptors 5, 7 and 8, respectively, owing to the much higher reactivity of the primary hydroxyl group over the secondary axial hydroxyl group in these structures. Stereoselective sialylation was accomplished using donor 10 with defined configuration established through X-ray crystallographic analysis. Target oligosaccharides 1-3 were then obtained by the systematic deprotection of intermediates 24, 27 and 29. With these target oligosaccharides 1-3 obtained, biological evaluations of these molecules as enzyme substrates was undertaken and selectin binding studies are planned.
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Affiliation(s)
- Jie Xia
- Molecular & Cellular Biophysics, Roswell Park Cancer Institute, Elm & Carlton Streets, Buffalo, NY 14263, USA
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31
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Ly HD, Lougheed B, Wakarchuk WW, Withers SG. Mechanistic studies of a retaining alpha-galactosyltransferase from Neisseria meningitidis. Biochemistry 2002; 41:5075-85. [PMID: 11955055 DOI: 10.1021/bi012031s] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lipopolysaccharyl alpha-galactosyltransferase from Neisseria meningitidis catalyzes the transfer of a galactosyl moiety from the activated donor UDP-Gal to glycoconjugates to yield an elongated saccharide product with net retention of anomeric configuration relative to the donor substrate. Through kinetic analyses in which the concentrations of both substrates are independently varied and through inhibition studies with dead-end analogues of both substrates and with the oligosaccharide product, we have demonstrated that this enzyme follows an ordered bi-bi kinetic mechanism. Various aspects of the chemical mechanism including the possible formation of a covalent glycosyl-enzyme intermediate were also probed using an assortment of strategies. While the results of these investigations were unable to clearly delineate the chemical mechanism of this enzyme, they provide important insights into the catalytic machinery surrounding the events involved in catalysis.
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Affiliation(s)
- Hoa D Ly
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1 Canada
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32
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Izumi M, Shen GJ, Wacowich-Sgarbi S, Nakatani T, Plettenburg O, Wong CH. Microbial glycosyltransferases for carbohydrate synthesis: alpha-2,3-sialyltransferase from Neisseria gonorrheae. J Am Chem Soc 2001; 123:10909-18. [PMID: 11686694 DOI: 10.1021/ja011382r] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The alpha-2,3-sialyltransferase from Neisseria gonorrheae was overproduced in E. coli for exploitation of its substrate specificity and synthetic utility. Several potential acceptor substrates were synthesized in this study, including mono- and oligosaccharides, glycolipids, and glycopeptides and their sulfate derivatives. Some CMP-sialic acid derivatives with modification at the C-5 position were also prepared for evaluation as donor substrates. It was found that the enzyme exhibits a broader acceptor substrate specificity when compared to other sialyltransferases, though the donor specificity is quite limited. Application of the enzyme to the preparative synthesis of representative sialyl glycoconjugates has been demonstrated. On the basis of this work and the work of others, this enzyme is the most versatile and synthetically useful among all sialyltransferases known to date, especially for the synthesis of sulfate-containing glycoconjugates.
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Affiliation(s)
- M Izumi
- Department of Chemistry, Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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33
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Takamura-Enya T, Watanabe M, Totsuka Y, Kanazawa T, Matsushima-Hibiya Y, Koyama K, Sugimura T, Wakabayashi K. Mono(ADP-ribosyl)ation of 2'-deoxyguanosine residue in DNA by an apoptosis-inducing protein, pierisin-1, from cabbage butterfly. Proc Natl Acad Sci U S A 2001; 98:12414-9. [PMID: 11592983 PMCID: PMC60068 DOI: 10.1073/pnas.221444598] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pierisin-1 is a potent apoptosis-inducing protein derived from the cabbage butterfly, Pieris rapae. It has been shown that pierisin-1 has an A small middle dotB structure-function organization like cholera or diphtheria toxin, where the "A" domain (N-terminal) exhibits ADP-ribosyltransferase activity. The present studies were designed to identify the target molecule for ADP-ribosylation by pierisin-1 in the presence of beta-[adenylate-(32)P]NAD, and we found DNA as the acceptor, but not protein as is the case with other bacteria-derived ADP-ribosylating toxins. ADP-ribosylation of tRNAs from yeast was also catalyzed by pierisin-1, but the efficiency was around 110 of that for calf thymus DNA. Pierisin-1 efficiently catalyzed the ADP-ribosylation of double-stranded DNA containing dG small middle dotdC, but not dA small middle dotdT pairs. The ADP-ribose moiety of NAD was transferred to the amino group at N(2) of 2'-deoxyguanosine to yield N(2)-(alpha-ADP-ribos-1-yl)-2'-deoxyguanosine and its beta form, which were determined by several spectral analyses including (1)H- and (13)C-NMR and mass spectrometry. The chemical structures were also ascertained by the independent synthesis of N(2)-(D-ribos-1-yl)-2'-deoxyguanosine, which is the characteristic moiety of ADP-ribosylated dG. Using the (32)P-postlabeling method, ADP-ribosylated dG could be detected in DNA from pierisin-1-treated HeLa cells, in which apoptosis was easily induced. Thus, the targets for ADP-ribosylation by pierisin-1 were concluded to be 2'-deoxyguanosine residues in DNA. This finding may open a new field regarding the biological significance of ADP-ribosylation.
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Affiliation(s)
- T Takamura-Enya
- Cancer Prevention Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-Ku, Tokyo 104-0045, Japan.
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34
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Abstract
There has been an exponential growth in interest of the functional roles of carbohydrates and cell surface glycoconjugates in the past 10 years. The importance of glycoconjugates as mediators of biosignals has stimulated investigation into simple and versatile methods for their synthesis. The synthesis of carbohydrates and glycoconjugates by combinatorial chemistry has gained considerable interest.
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Affiliation(s)
- S Nishimura
- Laboratory for Bio-macromolecules, Division of Biological Sciences, Graduate School of Science, Hokkaido University, 060-0810, Sapporo, Japan.
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