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Liu B, Furevi A, Perepelov AV, Guo X, Cao H, Wang Q, Reeves PR, Knirel YA, Wang L, Widmalm G. Structure and genetics of Escherichia coli O antigens. FEMS Microbiol Rev 2020; 44:655-683. [PMID: 31778182 PMCID: PMC7685785 DOI: 10.1093/femsre/fuz028] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 11/22/2019] [Indexed: 02/07/2023] Open
Abstract
Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and three (O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.
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Affiliation(s)
- Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Axel Furevi
- Department of Organic Chemistry, Arrhenius Laboratory, Svante Arrhenius väg 16C, Stockholm University, S-106 91 Stockholm, Sweden
| | - Andrei V Perepelov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect, 47, Moscow, Russia
| | - Xi Guo
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Hengchun Cao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Quan Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Peter R Reeves
- School of Molecular and Microbial Bioscience, University of Sydney, 2 Butilin Ave, Darlington NSW 2008, Sydney, Australia
| | - Yuriy A Knirel
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect, 47, Moscow, Russia
| | - Lei Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda Street, TEDA, Tianjing 300457, China
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, 23 Hongda Street, TEDA, Tianjin 300457, China
- Tianjin Key Laboratory of Microbial Functional Genomics, 23 Hongda Street, TEDA, Tianjin 300457, China
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Svante Arrhenius väg 16C, Stockholm University, S-106 91 Stockholm, Sweden
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Fontana C, Conde-Álvarez R, Ståhle J, Holst O, Iriarte M, Zhao Y, Arce-Gorvel V, Hanniffy S, Gorvel JP, Moriyón I, Widmalm G. Structural Studies of Lipopolysaccharide-defective Mutants from Brucella melitensis Identify a Core Oligosaccharide Critical in Virulence. J Biol Chem 2016; 291:7727-41. [PMID: 26867577 PMCID: PMC4817197 DOI: 10.1074/jbc.m115.701540] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Indexed: 11/07/2022] Open
Abstract
The structures of the lipooligosaccharides from Brucella melitensis mutants affected in the WbkD and ManBcore proteins have been fully characterized using NMR spectroscopy. The results revealed that disruption of wbkD gives rise to a rough lipopolysaccharide (R-LPS) with a complete core structure (β-d-Glcp-(1→4)-α-Kdop-(2→4)[β-d-GlcpN-(1→6)-β-d-GlcpN-(1→4)[β-d-GlcpN-(1→6)]-β-d-GlcpN-(1→3)-α-d-Manp-(1→5)]-α-Kdop-(2→6)-β-d-GlcpN3N4P-(1→6)-α-d-GlcpN3N1P), in addition to components lacking one of the terminal β-d-GlcpN and/or the β-d-Glcp residues (48 and 17%, respectively). These structures were identical to those of the R-LPS from B. melitensis EP, a strain simultaneously expressing both smooth and R-LPS, also studied herein. In contrast, disruption of manBcore gives rise to a deep-rough pentasaccharide core (β-d-Glcp-(1→4)-α-Kdop-(2→4)-α-Kdop-(2→6)-β-d-GlcpN3N4P-(1→6)-α-d-GlcpN3N1P) as the major component (63%), as well as a minor tetrasaccharide component lacking the terminal β-d-Glcp residue (37%). These results are in agreement with the predicted functions of the WbkD (glycosyltransferase involved in the biosynthesis of the O-antigen) and ManBcore proteins (phosphomannomutase involved in the biosynthesis of a mannosyl precursor needed for the biosynthesis of the core and O-antigen). We also report that deletion of B. melitensis wadC removes the core oligosaccharide branch not linked to the O-antigen causing an increase in overall negative charge of the remaining LPS inner section. This is in agreement with the mannosyltransferase role predicted for WadC and the lack of GlcpN residues in the defective core oligosaccharide. Despite carrying the O-antigen essential in B. melitensis virulence, the core deficiency in the wadC mutant structure resulted in a more efficient detection by innate immunity and attenuation, proving the role of the β-d-GlcpN-(1→6)-β-d-GlcpN-(1→4)[β-d-GlcpN-(1→6)]-β-d-GlcpN-(1→3)-α-d-Manp-(1→5) structure in virulence.
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Affiliation(s)
- Carolina Fontana
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - Raquel Conde-Álvarez
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Jonas Ståhle
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden
| | - Otto Holst
- the Division of Structural Biochemistry, Leibniz-Center for Medicine and Biosciences, Priority Area Asthma and Allergy, Research Center Borstel, Airway Research Center North, Member of the German Center for Lung Research, D-23845 Borstel, Germany
| | - Maite Iriarte
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Yun Zhao
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France
| | - Vilma Arce-Gorvel
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Seán Hanniffy
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Jean-Pierre Gorvel
- the Centre d'Immunologie de Marseille-Luminy Aix-Marseille University, UM2 Marseille, France, INSERM, U1104 Marseille, France, and CNRS, UMR7280 Marseille, France
| | - Ignacio Moriyón
- the Instituto de Salud Tropical, Instituto de Investigación Sanitaria de Navarra, and Departamento de Microbiología y Parasitología, Universidad de Navarra, c/Irunlarrea 1, 31008 Pamplona, Spain
| | - Göran Widmalm
- From the Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden,
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Zhao G, Wu B, Li L, Wang PG. O-antigen polymerase adopts a distributive mechanism for lipopolysaccharide biosynthesis. Appl Microbiol Biotechnol 2014; 98:4075-81. [PMID: 24557568 DOI: 10.1007/s00253-014-5552-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2013] [Revised: 12/09/2013] [Accepted: 01/18/2014] [Indexed: 01/08/2023]
Abstract
Bacterial lipopolysaccharide (LPS) is an essential cell envelope component for gram-negative bacteria. As the most variable region of LPS, O antigens serve as important virulence determinants for many bacteria and represent a promising carbohydrate source for glycoconjugate vaccines. In the Wzy-dependent O-antigen biosynthetic pathway, the integral membrane protein Wzy was shown to be the sole enzyme responsible for polymerization of O-repeat unit. Its catalytic mechanism, however, remains elusive. Herein, Wzy was successfully overexpressed in Escherichia coli with an N-terminal His10-tag. Blue native polyacrylamide gel electrophoresis (BN-PAGE) revealed that the Wzy protein exists in its native confirmation as a dimer. Subsequently, we chemo-enzymatically synthesized the substrates of Wzy, the lipid-PP-linked repeat units. Together with an optimized O-antigen visualization method, we monitored the production of reaction intermediates at varying times. We present here our result as the first biochemical evidence that Wzy functions in a distributive manner.
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Affiliation(s)
- Guohui Zhao
- Center for Diagnostics and Therapeutics and Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
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4
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Liu B, Knirel YA, Feng L, Perepelov AV, Senchenkova SN, Reeves PR, Wang L. Structural diversity in Salmonella O antigens and its genetic basis. FEMS Microbiol Rev 2013; 38:56-89. [PMID: 23848592 DOI: 10.1111/1574-6976.12034] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 05/15/2013] [Accepted: 07/05/2013] [Indexed: 11/30/2022] Open
Abstract
This review covers the structures and genetics of the 46 O antigens of Salmonella, a major pathogen of humans and domestic animals. The variation in structures underpins the serological specificity of the 46 recognized serogroups. The O antigen is important for the full function and virulence of many bacteria, and the considerable diversity of O antigens can confer selective advantage. Salmonella O antigens can be divided into two major groups: those which have N-acetylglucosamine (GlcNAc) or N-acetylgalactosamine (GalNAc) and those which have galactose (Gal) as the first sugar in the O unit. In recent years, we have determined 21 chemical structures and sequenced 28 gene clusters for GlcNAc-/GalNAc-initiated O antigens, thus completing the structure and DNA sequence data for the 46 Salmonella O antigens. The structures and gene clusters of the GlcNAc-/GalNAc-initiated O antigens were found to be highly diverse, and 24 of them were found to be identical or closely related to Escherichia coli O antigens. Sequence comparisons indicate that all or most of the shared gene clusters were probably present in the common ancestor, although alternative explanations are also possible. In contrast, the better-known eight Gal-initiated O antigens are closely related both in structures and gene cluster sequences.
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Affiliation(s)
- Bin Liu
- TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China; The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin, China
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5
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Escherichia coli O157:H7 LPS O-side chains and pO157 are required for killing Caenorhabditis elegans. Biochem Biophys Res Commun 2013; 436:388-93. [DOI: 10.1016/j.bbrc.2013.05.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 05/27/2013] [Indexed: 01/13/2023]
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Thoden JB, Reinhardt LA, Cook PD, Menden P, Cleland WW, Holden HM. Catalytic mechanism of perosamine N-acetyltransferase revealed by high-resolution X-ray crystallographic studies and kinetic analyses. Biochemistry 2012; 51:3433-44. [PMID: 22443398 DOI: 10.1021/bi300197h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
N-Acetylperosamine is an unusual dideoxysugar found in the O-antigens of some Gram-negative bacteria, including the pathogenic Escherichia coli strain O157:H7. The last step in its biosynthesis is catalyzed by PerB, an N-acetyltransferase belonging to the left-handed β-helix superfamily of proteins. Here we describe a combined structural and functional investigation of PerB from Caulobacter crescentus. For this study, three structures were determined to 1.0 Å resolution or better: the enzyme in complex with CoA and GDP-perosamine, the protein with bound CoA and GDP-N-acetylperosamine, and the enzyme containing a tetrahedral transition state mimic bound in the active site. Each subunit of the trimeric enzyme folds into two distinct regions. The N-terminal domain is globular and dominated by a six-stranded mainly parallel β-sheet. It provides most of the interactions between the protein and GDP-perosamine. The C-terminal domain consists of a left-handed β-helix, which has nearly seven turns. This region provides the scaffold for CoA binding. On the basis of these high-resolution structures, site-directed mutant proteins were constructed to test the roles of His 141 and Asp 142 in the catalytic mechanism. Kinetic data and pH-rate profiles are indicative of His 141 serving as a general base. In addition, the backbone amide group of Gly 159 provides an oxyanion hole for stabilization of the tetrahedral transition state. The pH-rate profiles are also consistent with the GDP-linked amino sugar substrate entering the active site in its unprotonated form. Finally, for this investigation, we show that PerB can accept GDP-3-deoxyperosamine as an alternative substrate, thus representing the production of a novel trideoxysugar.
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Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA
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7
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Characterization of the dehydratase WcbK and the reductase WcaG involved in GDP-6-deoxy-manno-heptose biosynthesis in Campylobacter jejuni. Biochem J 2011; 439:235-48. [PMID: 21711244 DOI: 10.1042/bj20110890] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The capsule of Campylobacter jejuni strain 81-176 comprises the unusual 6-deoxy-α-D-altro-heptose, whose biosynthesis and function are not known. In the present study, we characterized enzymes of the capsular cluster, WcbK and WcaG, to determine their role in 6-deoxy-altro-heptose synthesis. These enzymes are similar to the Yersinia pseudotuberculosis GDP-manno-heptose dehydratase/reductase DmhA/DmhB that we characterized previously. Capillary electrophoresis and MS analyses showed that WcbK is a GDP-manno-heptose dehydratase whose product can be reduced by WcaG, and that WcbK/WcaG can use the substrate GDP-mannose, although with lower efficiency than heptose. Comparison of kinetic parameters for WcbK and DmhA indicated that the relaxed substrate specificity of WcbK comes at the expense of catalytic performance on GDP-manno-heptose. Moreover, although WcbK/WcaG and DmhA/DmhB are involved in altro- versus manno-heptose synthesis respectively, the enzymes can be used interchangeably in mixed reactions. NMR spectroscopy analyses indicated conservation of the sugar manno configuration during catalysis by WcbK/WcaG. Therefore additional capsular enzymes may perform the C3 epimerization necessary to generate 6-deoxy-altro-heptose. Finally, a conserved residue (Thr(187) in WcbK) potentially involved in substrate specificity was identified by structural modelling of mannose and heptose dehydratases. Site-directed mutagenesis and kinetic analyses demonstrated its importance for enzymatic activity on heptose and mannose substrates.
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8
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Hutchinson E, Murphy B, Dunne T, Breen C, Rawlings B, Caffrey P. Redesign of polyene macrolide glycosylation: engineered biosynthesis of 19-(O)-perosaminyl-amphoteronolide B. ACTA ACUST UNITED AC 2010; 17:174-82. [PMID: 20189107 DOI: 10.1016/j.chembiol.2010.01.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 12/03/2009] [Accepted: 01/11/2010] [Indexed: 11/17/2022]
Abstract
Most polyene macrolide antibiotics are glycosylated with mycosamine (3,6-dideoxy-3-aminomannose). In the amphotericin B producer, Streptomyces nodosus, mycosamine biosynthesis begins with AmphDIII-catalyzed conversion of GDP-mannose to GDP-4-keto-6-deoxymannose. This is converted to GDP-3-keto-6-deoxymannose, which is transaminated to GDP-mycosamine by the AmphDII protein. The glycosyltransferase AmphDI transfers mycosamine to amphotericin aglycones (amphoteronolides). The aromatic heptaene perimycin is unusual among polyenes in that the sugar is perosamine (4,6-dideoxy-4-aminomannose), which is synthesized by direct transamination of GDP-4-keto-6-deoxymannose. Here, we use the Streptomyces aminophilus perDII perosamine synthase and perDI perosaminyltransferase genes to engineer biosynthesis of perosaminyl-amphoteronolide B in S. nodosus. Efficient production required a hybrid glycosyltransferase containing an N-terminal region of AmphDI and a C-terminal region of PerDI. This work will assist efforts to generate glycorandomized amphoteronolides for drug discovery.
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Affiliation(s)
- Eve Hutchinson
- School of Biomolecular and Biomedical Science and Centre for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
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9
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Bai S, Zhao J, Zhang Y, Huang W, Xu S, Chen H, Fan LM, Chen Y, Deng XW. Rapid and reliable detection of 11 food-borne pathogens using thin-film biosensor chips. Appl Microbiol Biotechnol 2010; 86:983-90. [PMID: 20091028 DOI: 10.1007/s00253-009-2417-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 01/10/2023]
Abstract
Traditional methods for identifying food-borne pathogens are time-consuming and laborious, so it is necessary to develop innovative methods for the rapid identification of food-borne pathogens. Here, we report the development of silicon-based optical thin-film biosensor chips for sensitive detection of 11 food-borne pathogens. Briefly, aldehyde-labeled probes were arrayed and covalently attached to a hydrazine-derivatized chip surface, and then, biotinylated polymerase chain reaction (PCR) amplicons were hybridized with the probes. After washing and brief incubation with an antibiotin immunoglobulin G-horseradish peroxidase conjugate and a precipitable horseradish peroxidase substrate, biotinylated chains bound to the probes were visualized as a color change on the chip surface (gold to blue/purple). Highly sensitive and accurate examination of PCR fragment targets can be completed within 30 min. This assay is extremely robust, sensitive, specific, and economical and can be adapted to different throughputs. Thus, a rapid, sensitive, and reliable technique for detecting 11 food-borne pathogens was successfully developed.
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Affiliation(s)
- Sulan Bai
- Key Laboratory of Genetics and Biotechnology, College of Life Sciences, Capital Normal University, Beijing, People's Republic of China
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10
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Cook PD, Carney AE, Holden HM. Accommodation of GDP-linked sugars in the active site of GDP-perosamine synthase. Biochemistry 2008; 47:10685-93. [PMID: 18795799 DOI: 10.1021/bi801309q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Perosamine (4-amino-4,6-dideoxy- d-mannose), or its N-acetylated form, is one of several dideoxy sugars found in the O-antigens of such infamous Gram-negative bacteria as Vibrio cholerae O1 and Escherichia coli O157:H7. It is added to the bacterial O-antigen via a nucleotide-linked version, namely GDP-perosamine. Three enzymes are required for the biosynthesis of GDP-perosamine starting from mannose 1-phosphate. The focus of this investigation is GDP-perosamine synthase from Caulobacter crescentus, which catalyzes the final step in GDP-perosamine synthesis, the conversion of GDP-4-keto-6-deoxymannose to GDP-perosamine. The enzyme is PLP-dependent and belongs to the aspartate aminotransferase superfamily. It contains the typically conserved active site lysine residue, which forms a Schiff base with the PLP cofactor. Two crystal structures were determined for this investigation: a site-directed mutant protein (K186A) complexed with GDP-perosamine and the wild-type enzyme complexed with an unnatural ligand, GDP-3-deoxyperosamine. These structures, determined to 1.6 and 1.7 A resolution, respectively, revealed the manner in which products, and presumably substrates, are accommodated within the active site pocket of GDP-perosamine synthase. Additional kinetic analyses using both the natural and unnatural substrates revealed that the K m for the unnatural substrate was unperturbed relative to that of the natural substrate, but the k cat was lowered by a factor of approximately 200. Taken together, these studies shed light on why GDP-perosamine synthase functions as an aminotransferase whereas another very similar PLP-dependent enzyme, GDP-4-keto-6-deoxy- d-mannose 3-dehydratase or ColD, catalyzes a dehydration reaction using the same substrate.
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Affiliation(s)
- Paul D Cook
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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Fabich AJ, Jones SA, Chowdhury FZ, Cernosek A, Anderson A, Smalley D, McHargue JW, Hightower GA, Smith JT, Autieri SM, Leatham MP, Lins JJ, Allen RL, Laux DC, Cohen PS, Conway T. Comparison of carbon nutrition for pathogenic and commensal Escherichia coli strains in the mouse intestine. Infect Immun 2008; 76:1143-52. [PMID: 18180286 PMCID: PMC2258830 DOI: 10.1128/iai.01386-07] [Citation(s) in RCA: 268] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 12/03/2007] [Accepted: 12/27/2007] [Indexed: 01/14/2023] Open
Abstract
The carbon sources that support the growth of pathogenic Escherichia coli O157:H7 in the mammalian intestine have not previously been investigated. In vivo, the pathogenic E. coli EDL933 grows primarily as single cells dispersed within the mucus layer that overlies the mouse cecal epithelium. We therefore compared the pathogenic strain and the commensal E. coli strain MG1655 modes of metabolism in vitro, using a mixture of the sugars known to be present in cecal mucus, and found that the two strains used the 13 sugars in a similar order and cometabolized as many as 9 sugars at a time. We conducted systematic mutation analyses of E. coli EDL933 and E. coli MG1655 by using lesions in the pathways used for catabolism of 13 mucus-derived sugars and five other compounds for which the corresponding bacterial gene system was induced in the transcriptome of cells grown on cecal mucus. Each of 18 catabolic mutants in both bacterial genetic backgrounds was fed to streptomycin-treated mice, together with the respective wild-type parent strain, and their colonization was monitored by fecal plate counts. None of the mutations corresponding to the five compounds not found in mucosal polysaccharides resulted in colonization defects. Based on the mutations that caused colonization defects, we determined that both E. coli EDL933 and E. coli MG1655 used arabinose, fucose, and N-acetylglucosamine in the intestine. In addition, E. coli EDL933 used galactose, hexuronates, mannose, and ribose, whereas E. coli MG1655 used gluconate and N-acetylneuraminic acid. The colonization defects of six catabolic lesions were found to be additive with E. coli EDL933 but not with E. coli MG1655. The data indicate that pathogenic E. coli EDL933 uses sugars that are not used by commensal E. coli MG1655 to colonize the mouse intestine. The results suggest a strategy whereby invading pathogens gain advantage by simultaneously consuming several sugars that may be available because they are not consumed by the commensal intestinal microbiota.
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Affiliation(s)
- Andrew J Fabich
- Advanced Center for Genome Technology, University of Oklahoma, Norman, Oklahoma 73019, USA
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12
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Cook PD, Holden HM. GDP-perosamine synthase: structural analysis and production of a novel trideoxysugar. Biochemistry 2008; 47:2833-40. [PMID: 18247575 DOI: 10.1021/bi702430d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Perosamine or 4-amino-4,6-dideoxy- d-mannose is an unusual sugar found in the O-antigens of some Gram-negative bacteria such as Vibrio cholerae O1 (the causative agent of cholera) or Escherichia coli O157:H7 (the leading cause of food-borne illnesses). It and similar deoxysugars are added to the O-antigens of bacteria via the action of glycosyltransferases that employ nucleotide-linked sugars as their substrates. The focus of this report is GDP-perosamine synthase, a PLP-dependent enzyme that catalyzes the last step in the formation of GDP-perosamine, namely, the amination of the sugar C-4'. Here we describe the three-dimensional structure of the enzyme from Caulobacter crescentus determined to a nominal resolution of 1.8 A and refined to an R-factor of 17.9%. The overall fold of the enzyme places it into the well-characterized aspartate aminotransferase superfamily. Each subunit of the dimeric enzyme contains a seven-stranded mixed beta-sheet, a two-stranded antiparallel beta-sheet, and 12 alpha-helices. Amino acid residues from both subunits form the active sites of the GDP-perosamine synthase dimer. Recently, the structure of another PLP-dependent enzyme, GDP-4-keto-6-deoxy- d-mannose-3-dehydratase (or ColD), was determined in our laboratory, and this enzyme employs the same substrate as GDP-perosamine synthase. Unlike GDP-perosamine synthase, however, ColD functions as a dehydratase that removes the sugar C-3' hydroxyl group. By purifying the ColD product and reacting it with purified GDP-perosamine synthase, we have produced a novel GDP-linked sugar, GDP-4-amino-3,4,6-trideoxy- d-mannose. Details describing the X-ray structural investigation of GDP-perosamine synthase and the enzymatic synthesis of GDP-4-amino-3,4,6-trideoxy- d-mannose are presented.
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Affiliation(s)
- Paul D Cook
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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13
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Albermann C, Beuttler H. Identification of the GDP-N-acetyl-d-perosamine producing enzymes from Escherichia coli O157:H7. FEBS Lett 2008; 582:479-84. [PMID: 18201574 DOI: 10.1016/j.febslet.2008.01.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 12/24/2007] [Accepted: 01/04/2008] [Indexed: 10/22/2022]
Abstract
GDP-N-acetyl-d-perosamine is a precursor of the LPS-O-antigen biosynthesis in Escherichia coli O157:H7. Like other GDP-6-deoxyhexoses, GDP-N-acetyl-d-perosamine is supposed to be synthesized via GDP-4-keto-6-deoxy-d-mannose, followed by a transamination- and an acetylation-reaction catalyzed by PerA and PerB. In this study, we have overproduced and purified PerA and PerB from E. coli O157:H7 in E. coli BL21. The recombinant proteins were partly characterized and the final product of the reaction catalyzed by PerB was shown to be GDP-N-acetyl-d-perosamine by chromatography, mass spectrometry, and 1H-NMR. The functional expression of PerB provides another enzymatically defined pathway for the synthesis of GDP-deoxyhexoses, which is needed to further study the corresponding glycosyltransferases in vitro.
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Affiliation(s)
- Christoph Albermann
- Institute of Microbiology, Universität Stuttgart, Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
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