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Mishra VK, Buter J, Blevins MS, Witte MD, Van Rhijn I, Moody DB, Brodbelt JS, Minnaard AJ. Total Synthesis of an Immunogenic Trehalose Phospholipid from Salmonella Typhi and Elucidation of Its sn-Regiochemistry by Mass Spectrometry. Org Lett 2019; 21:5126-5131. [PMID: 31247773 PMCID: PMC6614791 DOI: 10.1021/acs.orglett.9b01725] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Diphosphatidyltrehalose (diPT) is an immunogenic glycolipid, recently isolated from Salmonella Typhi. Despite rigorous structure elucidation, the sn-position of the acyl chains on the glycerol backbone had not been unequivocally established. A stereoselective synthesis of diPT and its regioisomer is reported herein. Using a hybrid MS3 approach combining collisional dissociation and ultraviolet photodissociation mass spectrometry for analysis of the regioisomers and natural diPT, the regiochemistry of the acyl chains of this abundant immunostimulatory glycolipid was established.
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Affiliation(s)
- Vivek K Mishra
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Jeffrey Buter
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Molly S Blevins
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
| | - Martin D Witte
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Ildiko Van Rhijn
- Department of Infectious Diseases and Immunology, School of Veterinary Medicine , Utrecht University , 3584 CL Utrecht , The Netherlands.,Department of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital , Harvard Medical School , Boston , Massachusetts 02115 , United States
| | - D Branch Moody
- Department of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital , Harvard Medical School , Boston , Massachusetts 02115 , United States
| | - Jennifer S Brodbelt
- Department of Chemistry , University of Texas , Austin , Texas 78712 , United States
| | - Adriaan J Minnaard
- Stratingh Institute for Chemistry , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
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2
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Sharipova RR, Garifullin BF, Sapunova AS, Voloshina AD, Kravchenko MA, Kataev VE. Synthesis and Biological Activity of 3,4,-Tri-О-Acetyl-N-Acetylglucosamine and Tetraacetylglucopyranose Conjugated with Alkyl Phosphates. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2019. [DOI: 10.1134/s1068162019020110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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de Carvalho AC, Girola N, de Figueiredo CR, Machado AC, de Medeiros LS, Guadagnin RC, Caseli L, Veiga TAM. Understanding the cytotoxic effects of new isovanillin derivatives through phospholipid Langmuir monolayers. Bioorg Chem 2018; 83:205-213. [PMID: 30380449 DOI: 10.1016/j.bioorg.2018.10.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 10/10/2018] [Accepted: 10/15/2018] [Indexed: 12/24/2022]
Abstract
Twenty-one isovanillin derivatives were prepared in order to evaluate their cytotoxic properties against the cancer cell lines B16F10-Nex2, HL-60, MCF-7, A2058 and HeLa. Among them, seven derivatives exhibited cytotoxic activity. We observed that for obtaining smaller IC50 values and for increasing the index of selectivity, two structural features are very important when compared with isovanillin (1); a hydroxymethyl group at C-1 and the replacement of the hydroxyl group at C-3 by different alkyl groups. As the lipophilicity of the compounds was changed, we decided to investigate the interaction of the cytotoxic isovallinin derivatives on cell membrane models through Langmuir monolayers by employing the lipids DPPC (1,2-diplamitoyl-sn-glycero-3-phosphocoline) and DPPS (1,2-diplamitoyl-sn-glycero-3-phosphoserine). The structural changes on the scaffold of the compounds modulated the interaction with the phospholipids at the air-water interface. These results were very important to understand the biophysical aspects related to the interaction of the cytotoxic compounds with the cancer cell membranes.
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Affiliation(s)
- Ana C de Carvalho
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Natália Girola
- Department of Microbiology, Immunology and Parasitology, Experimental Oncology Unit (UNONEX), Federal University of São Paulo, São Paulo, Brazil
| | - Carlos R de Figueiredo
- Department of Microbiology, Immunology and Parasitology, Experimental Oncology Unit (UNONEX), Federal University of São Paulo, São Paulo, Brazil
| | - André C Machado
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Lívia S de Medeiros
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Rafael C Guadagnin
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Luciano Caseli
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Thiago A M Veiga
- Department of Chemistry, Federal University of São Paulo, Diadema, São Paulo, Brazil.
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4
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Garifullin BF, Sharipova RR, Voloshina AD, Kravchenko MA, Kataev VE. Synthesis and Antitubercular and Antibacterial Activities of Triethylammonium 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranosyl Decyl Phosphate. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2018. [DOI: 10.1134/s1070428018090117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Identification and biochemical characterization of WbwB, a novel UDP-Gal: Neu5Ac-R α1,4-galactosyltransferase from the intestinal pathogen Escherichia coli serotype O104. Glycoconj J 2017; 35:65-76. [PMID: 29063990 DOI: 10.1007/s10719-017-9799-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 02/08/2023]
Abstract
The intestinal pathogen Escherichia coli serotype O104:H4 (ECO104) can cause bloody diarrhea and haemolytic uremic syndrome. The ECO104 O antigen has the unique repeating unit structure [4Galα1-4Neu5,7,9Ac3α2-3Galβ1-3GalNAcβ1-], which includes the mammalian sialyl-T antigen as an internal structure. Previously, we identified WbwC from ECO104 as the β3Gal-transferase that synthesizes the T antigen, and showed that α3-sialyl-transferase WbwA transfers sialic acid to the T antigen. Here we identify the wbwB gene product as a unique α1,4-Gal-transferase WbwB that transfers Gal from UDP-Gal to the terminal sialic acid residue of Neu5Acα2-3Galβ1-3GalNAcα-diphosphate-lipid acceptor. NMR analysis of the WbwB enzyme reaction product indicated that Galα1-4Neu5Acα2-3Galβ1-3GalNAcα-diphosphate-lipid was synthesized. WbwB from ECO104 has a unique acceptor specificity for terminal sialic acid as well as the diphosphate group in the acceptor. The characterization studies showed that WbwB does not require divalent metal ion as a cofactor. Mutagenesis identified Lys243 within an RKR motif and both Glu315 and Glu323 of the fourth EX7E motif as essential for the activity. WbwB is the final glycosyltransferase in the biosynthesis pathway of the ECO104 antigen repeating unit. This work contributes to knowledge of the biosynthesis of bacterial virulence factors.
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6
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Chen C, Hou X, Utkina N, Danilov L, Zhou D, Torgov V, Veselovsky V, Liu B, Feng L. Identification and biochemical characterization of a novel α-1,3-mannosyltransferase WfcD from Escherichia coli O141. Carbohydr Res 2017; 443-444:78-86. [PMID: 28402841 DOI: 10.1016/j.carres.2017.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/31/2017] [Accepted: 04/02/2017] [Indexed: 11/30/2022]
Abstract
Glycosyltransferases (GTs) catalyze the formation of regio- and stereospecific glycosidic linkages between specific sugar donors and recipients. In this study, the function of the wfcD gene from the Escherichia coli O141 O-antigen gene cluster encoding an α-1,3-mannosyltransferase that catalyzed the formation of the linkage Man(α1-3)-GlcNAc was biochemically characterized. WfcD was expressed in E. coli BL21 (DE3), and the enzymatic product was identified by liquid chromatography-mass spectrometry (LC-MS), collision-induced dissociation electrospray ionization ion trap multiple tandem MS (CID-ESI-IT-MSn) and glycosidase digestion using the donor substrate GDP-Man and the synthetic acceptor substrate decyl diphosphate 2-acetamido-2-deoxy-α-D-glucopyranose (GlcNAc-PP-De). The kinetic and physiochemical properties and the substrate specificity of WfcD were investigated. WfcD is the first characterized bacterial mannosyltransferase that acts on the Man(α1-3)-GlcNAc linkage. This study enhances our knowledge of the diverse functions of GTs.
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Affiliation(s)
- Chao Chen
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Xi Hou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Natalia Utkina
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Leonid Danilov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Dawei Zhou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Vladimir Torgov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Vladimir Veselovsky
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China
| | - Lu Feng
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjin, 300457, PR China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin, 300457, PR China.
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7
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Li L, Woodward RL, Han W, Qu J, Song J, Ma C, Wang PG. Chemoenzymatic synthesis of the bacterial polysaccharide repeating unit undecaprenyl pyrophosphate and its analogs. Nat Protoc 2016; 11:1280-98. [PMID: 27336706 DOI: 10.1038/nprot.2016.067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Polysaccharides are essential and immunologically relevant components of bacterial cell walls. These biomolecules can be found covalently attached to lipids (e.g., O-polysaccharide (PS) contains undecaprenyl and lipopolysaccharide (LPS) contains lipid A) or noncovalently associated with cell wells (e.g., capsular PS (CPS)). Although extensive genetic studies have indicated that the Wzy-dependent biosynthetic pathway is primarily responsible for producing such polysaccharides, in vitro biochemical studies are needed to determine, for example, which gene product is responsible for catalyzing each step in the pathway, and to reveal molecular details about the Wzx translocase, Wzy polymerase and O-PS chain-length determinant. Many of these biochemical studies require access to a structurally well-defined PS repeating unit undecaprenyl pyrophosphate (RU-PP-Und), the key building block in this pathway. We describe herein the chemoenzymatic synthesis of Escherichia coli (serotype O157) RU-PP-Und. This involves (i) chemical synthesis of precursor N-acetyl-D-galactosamine (GalNAc)-PP-Und (2 weeks) and (ii) enzymatic extension of the precursor to produce RU-PP-Und (2 weeks). Undecaprenyl phosphate and peracetylated GalNAc-1-phosphate are prepared from commercially available undecaprenol and peracetylated GalNAc. The chemical coupling of these two products, followed by structural confirmation (mass spectrometry and NMR) and deprotection, generates GalNAc-PP-Und. This compound is then sequentially modified by enzymes in the E. coli serotype O157 (E. coli O157) O-PS biosynthetic pathway. Three glycosyltransferases (GTs) are involved (WbdN, WbdO and WbdP) and they transfer glucose (Glc), L-fucose (L-Fuc) and N-acetylperosamine (PerNAc) onto GalNAc-PP-Und to form the intact RU-PP-Und in a stepwise manner. Final compounds and intermediates are confirmed by mass spectrometry. The procedure can be adapted to the synthesis of analogs with different PS or lipid moieties.
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Affiliation(s)
- Lei Li
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Robert L Woodward
- Department of Chemistry and Biochemistry, University of Mount Union, Alliance, Ohio, USA
| | - Weiqing Han
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Jingyao Qu
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Jing Song
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Cheng Ma
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
| | - Peng G Wang
- Department of Chemistry and Center for Diagnostics &Therapeutics, Georgia State University, Atlanta, Georgia, USA
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8
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010. MASS SPECTROMETRY REVIEWS 2015; 34:268-422. [PMID: 24863367 PMCID: PMC7168572 DOI: 10.1002/mas.21411] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 07/16/2013] [Accepted: 07/16/2013] [Indexed: 05/07/2023]
Abstract
This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.
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Affiliation(s)
- David J. Harvey
- Department of BiochemistryOxford Glycobiology InstituteUniversity of OxfordOxfordOX1 3QUUK
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9
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Biosynthesis of the Common Polysaccharide Antigen of Pseudomonas aeruginosa PAO1: Characterization and Role of GDP-D-Rhamnose:GlcNAc/GalNAc-Diphosphate-Lipid α1,3-D-Rhamnosyltransferase WbpZ. J Bacteriol 2015; 197:2012-9. [PMID: 25845842 DOI: 10.1128/jb.02590-14] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 03/30/2015] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The opportunistic pathogen Pseudomonas aeruginosa produces two major cell surface lipopolysaccharides, characterized by distinct O antigens, called common polysaccharide antigen (CPA) and O-specific antigen (OSA). CPA contains a polymer of D-rhamnose (D-Rha) in α1-2 and α1-3 linkages. Three putative glycosyltransferase genes, wbpX, wbpY, and wbpZ, are part of the CPA biosynthesis cluster. To characterize the enzymatic function of the wbpZ gene product, we chemically synthesized the donor substrate GDP-D-Rha and enzymatically synthesized GDP-D-[(3)H]Rha. Using nuclear magnetic resonance (NMR) spectroscopy, we showed that WbpZ transferred one D-Rha residue from GDP-D-Rha in α1-3 linkage to both GlcNAc- and GalNAc-diphosphate-lipid acceptor substrates. WbpZ is also capable of transferring D-mannose (D-Man) to these acceptors. Therefore, WbpZ has a relaxed specificity with respect to both acceptor and donor substrates. The diphosphate group of the acceptor, however, is required for activity. WbpZ does not require divalent metal ion for activity and exhibits an unusually high pH optimum of 9. WbpZ from PAO1 is therefore a GDP-D-Rha:GlcNAc/GalNAc-diphosphate-lipid α1,3-D-rhamnosyltransferase that has significant activity of GDP-D-Man:GlcNAc/GalNAc-diphosphate-lipid α1,3-D-mannosyltransferase. We used site-directed mutagenesis to replace the Asp residues of the two DXD motifs with Ala. Neither of the mutant constructs of wbpZ (D172A or D254A) could be used to rescue CPA biosynthesis in the ΔwbpZ knockout mutant in a complementation assay. This suggested that D172 and D254 are essential for WbpZ function. This work is the first detailed characterization study of a D-Rha-transferase and a critical step in the development of CPA synthesis inhibitors. IMPORTANCE This is the first characterization of a D-rhamnosyltransferase and shows that it is essential in Pseudomonas aeruginosa for the synthesis of the common polysaccharide antigen.
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Wang S, Czuchry D, Liu B, Vinnikova AN, Gao Y, Vlahakis JZ, Szarek WA, Wang L, Feng L, Brockhausen I. Characterization of two UDP-Gal:GalNAc-diphosphate-lipid β1,3-galactosyltransferases WbwC from Escherichia coli serotypes O104 and O5. J Bacteriol 2014; 196:3122-33. [PMID: 24957618 PMCID: PMC4135647 DOI: 10.1128/jb.01698-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 06/12/2014] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli displays O antigens on the outer membrane that play an important role in bacterial interactions with the environment. The O antigens of enterohemorrhagic E. coli O104 and O5 contain a Galβ1-3GalNAc disaccharide at the reducing end of the repeating unit. Several other O antigens contain this disaccharide, which is identical to the mammalian O-glycan core 1 or the cancer-associated Thomsen-Friedenreich (TF) antigen. We identified the wbwC genes responsible for the synthesis of the disaccharide in E. coli serotypes O104 and O5. To functionally characterize WbwC, an acceptor substrate analog, GalNAcα-diphosphate-phenylundecyl, was synthesized. WbwC reaction products were isolated by high-pressure liquid chromatography and analyzed by mass spectrometry, nuclear magnetic resonance, galactosidase and O-glycanase digestion, and anti-TF antibody. The results clearly showed that the Galβ1-3GalNAcα linkage was synthesized, confirming WbwCECO104 and WbwCECO5 as UDP-Gal:GalNAcα-diphosphate-lipid β1,3-Gal-transferases. Sequence analysis revealed a conserved DxDD motif, and mutagenesis showed the importance of these Asp residues in catalysis. The purified enzymes require divalent cations (Mn(2+)) for activity and are specific for UDP-Gal and GalNAc-diphosphate lipid substrates. WbwC was inhibited by bis-imidazolium salts having aliphatic chains of 18 to 22 carbons. This work will help to elucidate mechanisms of polysaccharide synthesis in pathogenic bacteria and provide technology for vaccine synthesis.
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Affiliation(s)
- Shuo Wang
- Department of Medicine and Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Diana Czuchry
- Department of Medicine and Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Bin Liu
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Anna N Vinnikova
- Department of Medicine and Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yin Gao
- Department of Medicine and Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Jason Z Vlahakis
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada
| | - Walter A Szarek
- Department of Chemistry, Queen's University, Kingston, Ontario, Canada
| | - Lei Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Lu Feng
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, China
| | - Inka Brockhausen
- Department of Medicine and Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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11
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Martinez Farias MA, Kincaid VA, Annamalai VR, Kiessling LL. Isoprenoid phosphonophosphates as glycosyltransferase acceptor substrates. J Am Chem Soc 2014; 136:8492-5. [PMID: 24866828 PMCID: PMC4073833 DOI: 10.1021/ja500622v] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
![]()
Glycosyltransferases that act on
polyprenol pyrophosphate substrates
are challenging to study because their lipid-linked substrates are
difficult to isolate from natural sources and arduous to synthesize.
To facilitate access to glycosyl acceptors, we assembled phosphonophosphate
analogues and showed these are effective substrate surrogates for
GlfT1, the essential product of mycobacterial gene Rv3782. Under chemically defined conditions, the galactofuranosyltransferase
GlfT1 catalyzes the formation of a tetrasaccharide sequence en route
to assembly of the mycobacterial galactan.
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Affiliation(s)
- Mario A Martinez Farias
- Department of Chemistry and ‡Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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12
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Gao Y, Vinnikova A, Brockhausen I. Functional identification of bacterial glucosyltransferase WbdN. Methods Mol Biol 2013; 1022:199-214. [PMID: 23765664 DOI: 10.1007/978-1-62703-465-4_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The outer membrane of gram-negative bacteria is stabilized by lipopolysaccharides (LPS). The O-antigenic polysaccharides of LPS are composed of repeating units that are exposed to and can interact with the environment. The glycosyltransferases that assemble these repeating units are encoded by the O-antigen gene cluster and utilize undecaprenol-phosphate-linked intermediates as natural acceptor substrates, and nucleotide sugars as donor substrates on the cytoplasmic face of the inner membrane. Many of the glycosyltransferase genes are known but the enzymatic functions of most of them remain to be identified. We describe here how the function of a recombinant glucosyltransferase WbdN from Escherichia coli O157 can be determined by NMR analysis of the enzyme product, using a synthetic acceptor substrate analog. A fluorescent acceptor substrate analog can be used in highly sensitive enzyme assays that allow the characterization of enzyme activity without the use of radioactive nucleotide sugar donor substrates.
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Affiliation(s)
- Yin Gao
- Department of Medicine, Division of Rheumatology, Queen's University, Kingston, Ontario, Canada
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13
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Gao Y, Liu B, Strum S, Schutzbach JS, Druzhinina TN, Utkina NS, Torgov VI, Danilov LL, Veselovsky VV, Vlahakis JZ, Szarek WA, Wang L, Brockhausen I. Biochemical characterization of WbdN, a β1,3-glucosyltransferase involved in O-antigen synthesis in enterohemorrhagic Escherichia coli O157. Glycobiology 2012; 22:1092-102. [PMID: 22556057 DOI: 10.1093/glycob/cws081] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The enterohemorrhagic O157 strain of Escherichia coli, which is one of the most well-known bacterial pathogens, has an O-antigen repeating unit structure with the sequence [-2-d-Rha4NAcα1-3-l-Fucα1-4-d-Glcβ1-3-d-GalNAcα1-]. The O-antigen gene cluster of E. coli O157 contains the genes responsible for the assembly of this repeating unit and includes wbdN. In spite of cloning many O-antigen genes, biochemical characterization has been done on very few enzymes involved in O-antigen synthesis. In this work, we expressed the wbdN gene in E. coli BL21, and the His-tagged protein was purified. WbdN activity was characterized using the donor substrate UDP-[(14)C]Glc and the synthetic acceptor substrate GalNAcα-O-PO(3)-PO(3)-(CH(2))(11)-O-Ph. The enzyme product was isolated by high pressure liquid chromatography, and mass spectrometry showed that one Glc residue was transferred to the acceptor by WbdN. Nuclear magnetic resonance analysis of the product structure indicated that Glc was β1-3 linked to GalNAc. WbdN contains a conserved DxD motif and requires divalent metal ions for full activity. WbdN activity has an optimal pH between 7 and 8 and is highly specific for UDP-Glc as the donor substrate. GalNAcα derivatives lacking the diphosphate group were inactive as substrates, and the enzyme did not transfer Glc to GlcNAcα-O-PO(3)-PO(3)-(CH(2))(11)-O-Ph. Our results illustrate that WbdN is a specific UDP-Glc:GalNAcα-diphosphate-lipid β1,3-Glc-transferase. The enzyme is a target for the development of inhibitors to block O157-antigen synthesis.
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Affiliation(s)
- Yin Gao
- Department of Medicine, Division of Rheumatology, Queen's University, Kingston, Ontario, Canada
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14
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Greenfield LK, Whitfield C. Synthesis of lipopolysaccharide O-antigens by ABC transporter-dependent pathways. Carbohydr Res 2012; 356:12-24. [PMID: 22475157 DOI: 10.1016/j.carres.2012.02.027] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 01/10/2023]
Abstract
The O-polysaccharide (O-PS; O-antigen) of bacterial lipopolysaccharides is made up of repeating units of one or more sugar residues and displays remarkable structural diversity. Despite the structural variations, there are only three strategies for O-PS assembly. The ATP-binding cassette (ABC)-transporter-dependent mechanism of O-PS biosynthesis is widespread. The Escherichia coli O9a and Klebsiella pneumoniae O2a antigens provide prototypes, which are distinguished by the fine details that link glycan polymerization and chain termination at the cytoplasmic face of the inner membrane to its export via the ABC transporter. Here, we describe the current understanding of these processes. Since glycoconjugate assembly complexes that utilize an ABC transporter-dependent pathway are widespread among the bacterial kingdom, the models described here are expected to extend beyond O-PS biosynthesis systems.
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Affiliation(s)
- Laura K Greenfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Biochemical characterization of UDP-Gal:GlcNAc-pyrophosphate-lipid β-1,4-Galactosyltransferase WfeD, a new enzyme from Shigella boydii type 14 that catalyzes the second step in O-antigen repeating-unit synthesis. J Bacteriol 2010; 193:449-59. [PMID: 21057010 DOI: 10.1128/jb.00737-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The O antigen is the outer part of the lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria and contains many repeats of an oligosaccharide unit. It contributes to antigenic variability and is essential to the full function and virulence of bacteria. Shigella is a Gram-negative human pathogen that causes diarrhea in humans. The O antigen of Shigella boydii type 14 consists of repeating oligosaccharide units with the structure [→6-d-Galpα1→4-d-GlcpAβ1→6-d-Galpβ1→4-d-Galpβ1→4-d-GlcpNAcβ1→]n. The wfeD gene in the O-antigen gene cluster of Shigella boydii type 14 was proposed to encode a galactosyltransferase (GalT) involved in O-antigen synthesis. We confirmed here that the wfeD gene product is a β4-GalT that synthesizes the Galβ1-4GlcNAcα-R linkage. WfeD was expressed in Escherichia coli, and the activity was characterized by using UDP-[³H]Gal as the donor substrate as well as the synthetic acceptor substrate GlcNAcα-pyrophosphate-(CH₂)₁₁-O-phenyl. The enzyme product was analyzed by liquid chromatography-mass spectrometry (LC-MS), high-performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR), and galactosidase digestion. The enzyme was shown to be specific for the UDP-Gal donor substrate and required pyrophosphate in the acceptor substrate. Divalent metal ions such as Mn²(+), Ni²(+), and, surprisingly, also Pb²(+) enhanced the enzyme activity. Mutational analysis showed that the Glu101 residue within a DxD motif is essential for activity, possibly by forming the catalytic nucleophile. The Lys211 residue was also shown to be required for activity and may be involved in the binding of the negatively charged acceptor substrate. Our study revealed that the β4-GalT WfeD is a novel enzyme that has virtually no sequence similarity to mammalian β4-GalT, although it catalyzes a similar reaction.
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