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Andrei V Perepelov - One of the best experts on this subject based on the ideXlab platform.

  • a gene cluster at an unusual chromosomal location responsible for the novel o Antigen synthesis in escherichia coli o62 by the abc transporter dependent pathway
    Glycobiology, 2017
    Co-Authors: Xi Hou, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Bin Liu, Xi Guo, Lei Wang
    Abstract:

    The O-Antigen is a part of the outer membrane of Gram-negative bacteria and is related to bacterial virulence. It is one of the most variable cell constituents, and its structural diversity is almost entirely due to genetic variation of the O-Antigen gene cluster. In this study, the O-Antigen Structure of Escherichia coli O62 was elucidated by chemical analysis and nuclear magnetic resonance spectroscopy, but showing not consistent with the O-Antigen gene cluster between conserved genes galF and gnd reported earlier. The complete genome of E. coli O62 was then sequenced and analyzed, and another O-Antigen gene cluster was found and characterized that correlated perfectly with the established O-Antigen Structure. A deletion and complementation experiment confirmed the functionality of the novel gene cluster and demonstrated that the O62-Antigen is synthesized by the ABC transporter-dependent system. To our knowledge, this is the first report that the O-Antigen gene cluster is positioned at a novel locus in E. coli. Comparative analysis indicated that E. coli O62 likely originated from E. coli O68 via an IS event resulting in the repression of the O68-Antigen synthesis, followed by the acquisition of a novel O-Antigen gene cluster from Enterobacter aerogenes.

  • Structure elucidation and analysis of biosynthesis genes of the o Antigen of escherichia coli o131 containing n acetylneuraminic acid
    Carbohydrate Research, 2016
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Bin Liu, Xi Guo, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) of Escherichia coli O131 was studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following Structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: →8)-α-Neup5Ac-(2 → 6)-β- D -Galp-(1 → 6)-β-D-Galp-(1 → 3)-β-D-GalpNAc-(1→ The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the E. coli O131-Antigen Structure.

  • identification of an o acyltransferase gene oacb that mediates 3 and 4 o acetylation of rhamnose iii in shigella flexneri o Antigens
    Journal of Bacteriology, 2014
    Co-Authors: Jianping Wang, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Ruiting Lan, Yiting Wang, Xia Luo, Qiangzheng Sun
    Abstract:

    O Antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O Antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-Rhap(III)-(1→2)-α-l-Rhap(II)-(1→3)-α-l-Rhap(I)-(1→3)-β-d-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, two new O-Antigen modifications, namely, O-acetylation at position 3 or 4 of Rha(III) and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on Rha(III) was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on Rha(III), revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-Antigen Structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-Antigen backbone Structure. The oacB gene is carried by a transposon-like Structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-Antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-Antigen modifications and shed light on the origin of new O-Antigen variants.

  • o Antigen Structure of shigella flexneri serotype yv and effect of the lpt o gene variation on phosphoethanolamine modification of s flexneri o Antigens
    Glycobiology, 2013
    Co-Authors: Yuriy A Knirel, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Ruiting Lan, Jianping Wang, Yan Wang, Yanwen Xiong, Qiangzheng Sun
    Abstract:

    Shigella flexneri is the major human pathogen causing shigellosis. O-Antigens of all S. flexneri serotypes (except for serotype 6) share the →2)-α-l-Rhap(III)-(1 → 2)-α-l-Rhap(II)-(1 → 3)-α-l-Rhap(I)-(1 → 3)-β-d-GlcpNAc-(1→ basic O-unit, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation at various positions. Recently, in serotype X and 4a variants called Xv and 4av, respectively, O-Antigen modification with phosphoethanolamine (PEtN) has been identified, which is encoded by a plasmid-borne gene (lpt-O) for a PEtN-transferase and confers the monoclonal antibody IV-1(MASF IV-1) determinant to the bacteria. In this study, we elucidated the O-Antigen Structure of serotype Yv, another MASF IV-1-positive novel variant of S. flexneri. The serotype Yv O-Antigen has the same basic carbohydrate backbone Structure as that of the "classical" serotype Y, but differs in the presence of PEtN at position 3 of Rha(III) (major) or both Rha(II) and Rha(III) (minor). This pattern is similar to that of serotype 4av, but different from the pattern of serotype Xv, which is characterized by major PEtN modification on Rha(II). In serotype Yv, mono- and bisphosphorylated O-units generate a block-copolymeric Structure, the former being partially O-acetylated at position 6 of GlcNAc and the latter lacking O-acetylation. Functional analysis revealed a correlation between the serotype-specific PEtN modification pattern and the lpt-O variation in different serotypes: lpt-O(RII) in serotype Xv is better tuned for phosphorylation of Rha(II) and lpt-O(RIII) in serotypes Yv and 4av for phosphorylation of Rha(III). These data enhance our knowledge of S. flexneri serotype conversion mechanisms and help to understand the biosynthesis process of the new O-Antigen variants.

  • Structure and gene cluster of the o Antigen of escherichia coli o110 containing an amide of d galacturonic acid with d allothreonine
    Carbohydrate Research, 2013
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Lu Feng, Lei Wang, Quan Wang, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O110. The following Structure of the linear tetrasaccharide O-unit of the O-polysaccharide was established by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy: Download : Download full-size image where aThr indicates allothreonine. The O-Antigen gene cluster of E. coli O110 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-Antigen Structure.

Robert Seckler - One of the best experts on this subject based on the ideXlab platform.

  • tailspike interactions with lipopolysaccharide effect dna ejection from phage p22 particles in vitro
    Journal of Biological Chemistry, 2010
    Co-Authors: Dorothee Andres, Ulrich Baxa, Christin Hanke, Anait Seul, Stefanie Barbirz, Robert Seckler
    Abstract:

    Initial attachment of bacteriophage P22 to the Salmonella host cell is known to be mediated by interactions between lipopolysaccharide (LPS) and the phage tailspike proteins (TSP), but the events that subsequently lead to DNA injection into the bacterium are unknown. We used the binding of a fluorescent dye and DNA accessibility to DNase and restriction enzymes to analyze DNA ejection from phage particles in vitro. Ejection was specifically triggered by aggregates of purified Salmonella LPS but not by LPS with different O-Antigen Structure, by lipid A, phospholipids, or soluble O-Antigen polysaccharide. This suggests that P22 does not use a secondary receptor at the bacterial outer membrane surface. Using phage particles reconstituted with purified mutant TSP in vitro, we found that the endorhamnosidase activity of TSP degrading the O-Antigen polysaccharide was required prior to DNA ejection in vitro and DNA replication in vivo. If, however, LPS was pre-digested with soluble TSP, it was no longer able to trigger DNA ejection, even though it still contained five O-Antigen oligosaccharide repeats. Together with known data on the Structure of LPS and phage P22, our results suggest a molecular model. In this model, tailspikes position the phage particles on the outer membrane surface for DNA ejection. They force gp26, the central needle and plug protein of the phage tail machine, through the core oligosaccharide layer and into the hydrophobic portion of the outer membrane, leading to refolding of the gp26 lazo-domain, release of the plug, and ejection of DNA and pilot proteins.

  • mutations improving the folding of phage p22 tailspike protein affect its receptor binding activity
    Journal of Molecular Biology, 1999
    Co-Authors: Ulrich Baxa, Andrej Weintraub, Stefan Steinbacher, Robert Huber, Robert Seckler
    Abstract:

    Abstract Four previously isolated mutations in Salmonella phage P22 tailspike protein were used to study the relationship between protein stability, folding, and function. Tailspike protein binds and hydrolyzes the repetitive O-Antigen Structure in Salmonella lipopolysaccharide. Four mutations (V331G, V331A, A334V, A334I) are known to increase the folding efficiency, and two of them (at position 331) also increase the thermal stability of the protein. Octasaccharides comprising two repeating units of the O-Antigens from two different Salmonella strains were employed to analyze the receptor binding function of the mutant proteins. Their endorhamnosidase enzymatic activity was assayed with the aid of a fluorescence-labeled dodecasaccharide. Both V331A and V331G were found to strongly affect O-Antigen binding. Octasaccharide binding affinities of the mutant proteins are reduced tenfold and 200-fold, corresponding to a loss of 17 % and 36 % of the standard free energy of binding, respectively. Both mutations at position 334 affected O-Antigen binding only slightly (ΔΔGB03≈1 kJ/mol), but these mutations reduce the thermal stability of the protein. The observed effects on the endoglycosidase activity are fully explained by the changes in substrate binding, suggesting that neither of the mutations affect the catalytic rate. Crystal Structures of all four mutants were determined to a resolution of 2.0 A. Except for the partly or completely missing side-chain, no significant changes compared to the wild-type protein Structure were found for the mutants at position 331, whereas a small but significant backbone displacement around the mutation site in A334V and A334I may explain the observed thermal destabilization.

  • interactions of phage p22 tails with their cellular receptor salmonella o Antigen polysaccharide
    Biophysical Journal, 1996
    Co-Authors: Ulrich Baxa, Andrej Weintraub, Stefan Steinbacher, Robert Huber, Stefan Miller, Robert Seckler
    Abstract:

    Bacteriophage P22 binds to its cell surface receptor, the repetitive O-Antigen Structure in Salmonella lipopolysaccharide, by its six homotrimeric tailspikes. Receptor binding by soluble tailspikes and the receptor-inactivating endorhamnosidase activity of the tailspike protein were studied using octa- and dodecasaccharides comprising two and three O-Antigen repeats of Salmonella enteritidis and Salmonella typhimurium lipopolysaccharides. Wild-type tailspike protein and three mutants (D392N, D395N, and E359Q) with defective endorhamnosidase activity were used. Oligosaccharide binding to all three subunits, measured by a tryptophan fluorescence quench or by fluorescence depolarization of a coumarin label attached to the reducing end of the dodecasaccharide, occurs independently. At 10 degrees C, the binding affinities of all four proteins to oligosaccharides from both bacterial strains are identical within experimental error, and the binding constants for octa- and dodecasaccharides are 1 x 10(6) M(-1) and 2 x 10(6) M(-1), proving that two O-Antigen repeats are sufficient for lipopolysaccharide recognition by the tailspike. Equilibration with the oligosaccharides occurs rapidly, but the endorhamnosidase produces only one cleavage every 100 s at 10 degrees C or about 2 min(-1) at the bacterial growth temperature. Thus, movement of virions in the lipopolysaccharide layer before DNA injection may involve the release and rebinding of individual tailspikes rather than hydrolysis of the O-Antigen.

Alexander S Shashkov - One of the best experts on this subject based on the ideXlab platform.

  • a gene cluster at an unusual chromosomal location responsible for the novel o Antigen synthesis in escherichia coli o62 by the abc transporter dependent pathway
    Glycobiology, 2017
    Co-Authors: Xi Hou, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Bin Liu, Xi Guo, Lei Wang
    Abstract:

    The O-Antigen is a part of the outer membrane of Gram-negative bacteria and is related to bacterial virulence. It is one of the most variable cell constituents, and its structural diversity is almost entirely due to genetic variation of the O-Antigen gene cluster. In this study, the O-Antigen Structure of Escherichia coli O62 was elucidated by chemical analysis and nuclear magnetic resonance spectroscopy, but showing not consistent with the O-Antigen gene cluster between conserved genes galF and gnd reported earlier. The complete genome of E. coli O62 was then sequenced and analyzed, and another O-Antigen gene cluster was found and characterized that correlated perfectly with the established O-Antigen Structure. A deletion and complementation experiment confirmed the functionality of the novel gene cluster and demonstrated that the O62-Antigen is synthesized by the ABC transporter-dependent system. To our knowledge, this is the first report that the O-Antigen gene cluster is positioned at a novel locus in E. coli. Comparative analysis indicated that E. coli O62 likely originated from E. coli O68 via an IS event resulting in the repression of the O68-Antigen synthesis, followed by the acquisition of a novel O-Antigen gene cluster from Enterobacter aerogenes.

  • Structure elucidation and analysis of biosynthesis genes of the o Antigen of escherichia coli o131 containing n acetylneuraminic acid
    Carbohydrate Research, 2016
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Bin Liu, Xi Guo, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) of Escherichia coli O131 was studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following Structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: →8)-α-Neup5Ac-(2 → 6)-β- D -Galp-(1 → 6)-β-D-Galp-(1 → 3)-β-D-GalpNAc-(1→ The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the E. coli O131-Antigen Structure.

  • identification of an o acyltransferase gene oacb that mediates 3 and 4 o acetylation of rhamnose iii in shigella flexneri o Antigens
    Journal of Bacteriology, 2014
    Co-Authors: Jianping Wang, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Ruiting Lan, Yiting Wang, Xia Luo, Qiangzheng Sun
    Abstract:

    O Antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O Antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-Rhap(III)-(1→2)-α-l-Rhap(II)-(1→3)-α-l-Rhap(I)-(1→3)-β-d-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, two new O-Antigen modifications, namely, O-acetylation at position 3 or 4 of Rha(III) and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on Rha(III) was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on Rha(III), revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-Antigen Structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-Antigen backbone Structure. The oacB gene is carried by a transposon-like Structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-Antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-Antigen modifications and shed light on the origin of new O-Antigen variants.

  • o Antigen Structure of shigella flexneri serotype yv and effect of the lpt o gene variation on phosphoethanolamine modification of s flexneri o Antigens
    Glycobiology, 2013
    Co-Authors: Yuriy A Knirel, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Ruiting Lan, Jianping Wang, Yan Wang, Yanwen Xiong, Qiangzheng Sun
    Abstract:

    Shigella flexneri is the major human pathogen causing shigellosis. O-Antigens of all S. flexneri serotypes (except for serotype 6) share the →2)-α-l-Rhap(III)-(1 → 2)-α-l-Rhap(II)-(1 → 3)-α-l-Rhap(I)-(1 → 3)-β-d-GlcpNAc-(1→ basic O-unit, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation at various positions. Recently, in serotype X and 4a variants called Xv and 4av, respectively, O-Antigen modification with phosphoethanolamine (PEtN) has been identified, which is encoded by a plasmid-borne gene (lpt-O) for a PEtN-transferase and confers the monoclonal antibody IV-1(MASF IV-1) determinant to the bacteria. In this study, we elucidated the O-Antigen Structure of serotype Yv, another MASF IV-1-positive novel variant of S. flexneri. The serotype Yv O-Antigen has the same basic carbohydrate backbone Structure as that of the "classical" serotype Y, but differs in the presence of PEtN at position 3 of Rha(III) (major) or both Rha(II) and Rha(III) (minor). This pattern is similar to that of serotype 4av, but different from the pattern of serotype Xv, which is characterized by major PEtN modification on Rha(II). In serotype Yv, mono- and bisphosphorylated O-units generate a block-copolymeric Structure, the former being partially O-acetylated at position 6 of GlcNAc and the latter lacking O-acetylation. Functional analysis revealed a correlation between the serotype-specific PEtN modification pattern and the lpt-O variation in different serotypes: lpt-O(RII) in serotype Xv is better tuned for phosphorylation of Rha(II) and lpt-O(RIII) in serotypes Yv and 4av for phosphorylation of Rha(III). These data enhance our knowledge of S. flexneri serotype conversion mechanisms and help to understand the biosynthesis process of the new O-Antigen variants.

  • Structure and gene cluster of the o Antigen of escherichia coli o110 containing an amide of d galacturonic acid with d allothreonine
    Carbohydrate Research, 2013
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Lu Feng, Lei Wang, Quan Wang, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O110. The following Structure of the linear tetrasaccharide O-unit of the O-polysaccharide was established by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy: Download : Download full-size image where aThr indicates allothreonine. The O-Antigen gene cluster of E. coli O110 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-Antigen Structure.

Sofya N Senchenkova - One of the best experts on this subject based on the ideXlab platform.

  • a gene cluster at an unusual chromosomal location responsible for the novel o Antigen synthesis in escherichia coli o62 by the abc transporter dependent pathway
    Glycobiology, 2017
    Co-Authors: Xi Hou, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Bin Liu, Xi Guo, Lei Wang
    Abstract:

    The O-Antigen is a part of the outer membrane of Gram-negative bacteria and is related to bacterial virulence. It is one of the most variable cell constituents, and its structural diversity is almost entirely due to genetic variation of the O-Antigen gene cluster. In this study, the O-Antigen Structure of Escherichia coli O62 was elucidated by chemical analysis and nuclear magnetic resonance spectroscopy, but showing not consistent with the O-Antigen gene cluster between conserved genes galF and gnd reported earlier. The complete genome of E. coli O62 was then sequenced and analyzed, and another O-Antigen gene cluster was found and characterized that correlated perfectly with the established O-Antigen Structure. A deletion and complementation experiment confirmed the functionality of the novel gene cluster and demonstrated that the O62-Antigen is synthesized by the ABC transporter-dependent system. To our knowledge, this is the first report that the O-Antigen gene cluster is positioned at a novel locus in E. coli. Comparative analysis indicated that E. coli O62 likely originated from E. coli O68 via an IS event resulting in the repression of the O68-Antigen synthesis, followed by the acquisition of a novel O-Antigen gene cluster from Enterobacter aerogenes.

  • Structure elucidation and analysis of biosynthesis genes of the o Antigen of escherichia coli o131 containing n acetylneuraminic acid
    Carbohydrate Research, 2016
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Bin Liu, Xi Guo, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) of Escherichia coli O131 was studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following Structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: →8)-α-Neup5Ac-(2 → 6)-β- D -Galp-(1 → 6)-β-D-Galp-(1 → 3)-β-D-GalpNAc-(1→ The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the E. coli O131-Antigen Structure.

  • identification of an o acyltransferase gene oacb that mediates 3 and 4 o acetylation of rhamnose iii in shigella flexneri o Antigens
    Journal of Bacteriology, 2014
    Co-Authors: Jianping Wang, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Ruiting Lan, Yiting Wang, Xia Luo, Qiangzheng Sun
    Abstract:

    O Antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O Antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-Rhap(III)-(1→2)-α-l-Rhap(II)-(1→3)-α-l-Rhap(I)-(1→3)-β-d-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, two new O-Antigen modifications, namely, O-acetylation at position 3 or 4 of Rha(III) and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on Rha(III) was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on Rha(III), revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-Antigen Structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-Antigen backbone Structure. The oacB gene is carried by a transposon-like Structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-Antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-Antigen modifications and shed light on the origin of new O-Antigen variants.

  • o Antigen Structure of shigella flexneri serotype yv and effect of the lpt o gene variation on phosphoethanolamine modification of s flexneri o Antigens
    Glycobiology, 2013
    Co-Authors: Yuriy A Knirel, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Ruiting Lan, Jianping Wang, Yan Wang, Yanwen Xiong, Qiangzheng Sun
    Abstract:

    Shigella flexneri is the major human pathogen causing shigellosis. O-Antigens of all S. flexneri serotypes (except for serotype 6) share the →2)-α-l-Rhap(III)-(1 → 2)-α-l-Rhap(II)-(1 → 3)-α-l-Rhap(I)-(1 → 3)-β-d-GlcpNAc-(1→ basic O-unit, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation at various positions. Recently, in serotype X and 4a variants called Xv and 4av, respectively, O-Antigen modification with phosphoethanolamine (PEtN) has been identified, which is encoded by a plasmid-borne gene (lpt-O) for a PEtN-transferase and confers the monoclonal antibody IV-1(MASF IV-1) determinant to the bacteria. In this study, we elucidated the O-Antigen Structure of serotype Yv, another MASF IV-1-positive novel variant of S. flexneri. The serotype Yv O-Antigen has the same basic carbohydrate backbone Structure as that of the "classical" serotype Y, but differs in the presence of PEtN at position 3 of Rha(III) (major) or both Rha(II) and Rha(III) (minor). This pattern is similar to that of serotype 4av, but different from the pattern of serotype Xv, which is characterized by major PEtN modification on Rha(II). In serotype Yv, mono- and bisphosphorylated O-units generate a block-copolymeric Structure, the former being partially O-acetylated at position 6 of GlcNAc and the latter lacking O-acetylation. Functional analysis revealed a correlation between the serotype-specific PEtN modification pattern and the lpt-O variation in different serotypes: lpt-O(RII) in serotype Xv is better tuned for phosphorylation of Rha(II) and lpt-O(RIII) in serotypes Yv and 4av for phosphorylation of Rha(III). These data enhance our knowledge of S. flexneri serotype conversion mechanisms and help to understand the biosynthesis process of the new O-Antigen variants.

  • Structure and gene cluster of the o Antigen of escherichia coli o110 containing an amide of d galacturonic acid with d allothreonine
    Carbohydrate Research, 2013
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Lu Feng, Lei Wang, Quan Wang, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O110. The following Structure of the linear tetrasaccharide O-unit of the O-polysaccharide was established by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy: Download : Download full-size image where aThr indicates allothreonine. The O-Antigen gene cluster of E. coli O110 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-Antigen Structure.

Yuriy A Knirel - One of the best experts on this subject based on the ideXlab platform.

  • a gene cluster at an unusual chromosomal location responsible for the novel o Antigen synthesis in escherichia coli o62 by the abc transporter dependent pathway
    Glycobiology, 2017
    Co-Authors: Xi Hou, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Bin Liu, Xi Guo, Lei Wang
    Abstract:

    The O-Antigen is a part of the outer membrane of Gram-negative bacteria and is related to bacterial virulence. It is one of the most variable cell constituents, and its structural diversity is almost entirely due to genetic variation of the O-Antigen gene cluster. In this study, the O-Antigen Structure of Escherichia coli O62 was elucidated by chemical analysis and nuclear magnetic resonance spectroscopy, but showing not consistent with the O-Antigen gene cluster between conserved genes galF and gnd reported earlier. The complete genome of E. coli O62 was then sequenced and analyzed, and another O-Antigen gene cluster was found and characterized that correlated perfectly with the established O-Antigen Structure. A deletion and complementation experiment confirmed the functionality of the novel gene cluster and demonstrated that the O62-Antigen is synthesized by the ABC transporter-dependent system. To our knowledge, this is the first report that the O-Antigen gene cluster is positioned at a novel locus in E. coli. Comparative analysis indicated that E. coli O62 likely originated from E. coli O68 via an IS event resulting in the repression of the O68-Antigen synthesis, followed by the acquisition of a novel O-Antigen gene cluster from Enterobacter aerogenes.

  • Structure elucidation and analysis of biosynthesis genes of the o Antigen of escherichia coli o131 containing n acetylneuraminic acid
    Carbohydrate Research, 2016
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Bin Liu, Xi Guo, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) of Escherichia coli O131 was studied by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy. The following Structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: →8)-α-Neup5Ac-(2 → 6)-β- D -Galp-(1 → 6)-β-D-Galp-(1 → 3)-β-D-GalpNAc-(1→ The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in agreement with the E. coli O131-Antigen Structure.

  • identification of an o acyltransferase gene oacb that mediates 3 and 4 o acetylation of rhamnose iii in shigella flexneri o Antigens
    Journal of Bacteriology, 2014
    Co-Authors: Jianping Wang, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Yuriy A Knirel, Ruiting Lan, Yiting Wang, Xia Luo, Qiangzheng Sun
    Abstract:

    O Antigen (O polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of Gram-negative bacteria. Most O Antigens of Shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-Rhap(III)-(1→2)-α-l-Rhap(II)-(1→3)-α-l-Rhap(I)-(1→3)-β-d-GlcpNAc-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. The known modifications include glucosylation on various sugar residues, O-acetylation on Rha(I), and phosphorylation with phosphoethanolamine on Rha(II) or/and Rha(III). Recently, two new O-Antigen modifications, namely, O-acetylation at position 3 or 4 of Rha(III) and position 6 of GlcNAc, have been identified in several S. flexneri serotypes. In this work, the genetic basis for the 3/4-O-acetylation on Rha(III) was elucidated. Bioinformatic analysis of the genome of S. flexneri serotype 2a strain Sf301, which carries 3/4-O-acetylation on Rha(III), revealed an O-acyltransferase gene designated oacB. Genetic studies combined with O-Antigen Structure analysis demonstrated that this gene is responsible for the 3/4-O-acetylation in serotypes 1a, 1b, 2a, 5a, and Y but not serotype 6, which has a different O-Antigen backbone Structure. The oacB gene is carried by a transposon-like Structure located in the proA-adrA region on the chromosome, which represents a novel mechanism of mobilization of O-Antigen modification factors in S. flexneri. These findings enhance our knowledge of S. flexneri O-Antigen modifications and shed light on the origin of new O-Antigen variants.

  • o Antigen Structure of shigella flexneri serotype yv and effect of the lpt o gene variation on phosphoethanolamine modification of s flexneri o Antigens
    Glycobiology, 2013
    Co-Authors: Yuriy A Knirel, Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Ruiting Lan, Jianping Wang, Yan Wang, Yanwen Xiong, Qiangzheng Sun
    Abstract:

    Shigella flexneri is the major human pathogen causing shigellosis. O-Antigens of all S. flexneri serotypes (except for serotype 6) share the →2)-α-l-Rhap(III)-(1 → 2)-α-l-Rhap(II)-(1 → 3)-α-l-Rhap(I)-(1 → 3)-β-d-GlcpNAc-(1→ basic O-unit, whereas differences between the serotypes are conferred by phage-encoded glucosylation and/or O-acetylation at various positions. Recently, in serotype X and 4a variants called Xv and 4av, respectively, O-Antigen modification with phosphoethanolamine (PEtN) has been identified, which is encoded by a plasmid-borne gene (lpt-O) for a PEtN-transferase and confers the monoclonal antibody IV-1(MASF IV-1) determinant to the bacteria. In this study, we elucidated the O-Antigen Structure of serotype Yv, another MASF IV-1-positive novel variant of S. flexneri. The serotype Yv O-Antigen has the same basic carbohydrate backbone Structure as that of the "classical" serotype Y, but differs in the presence of PEtN at position 3 of Rha(III) (major) or both Rha(II) and Rha(III) (minor). This pattern is similar to that of serotype 4av, but different from the pattern of serotype Xv, which is characterized by major PEtN modification on Rha(II). In serotype Yv, mono- and bisphosphorylated O-units generate a block-copolymeric Structure, the former being partially O-acetylated at position 6 of GlcNAc and the latter lacking O-acetylation. Functional analysis revealed a correlation between the serotype-specific PEtN modification pattern and the lpt-O variation in different serotypes: lpt-O(RII) in serotype Xv is better tuned for phosphorylation of Rha(II) and lpt-O(RIII) in serotypes Yv and 4av for phosphorylation of Rha(III). These data enhance our knowledge of S. flexneri serotype conversion mechanisms and help to understand the biosynthesis process of the new O-Antigen variants.

  • Structure and gene cluster of the o Antigen of escherichia coli o110 containing an amide of d galacturonic acid with d allothreonine
    Carbohydrate Research, 2013
    Co-Authors: Andrei V Perepelov, Sofya N Senchenkova, Alexander S Shashkov, Lu Feng, Lei Wang, Quan Wang, Yuriy A Knirel
    Abstract:

    Abstract The O-polysaccharide (O-Antigen) was isolated by mild acid degradation of the lipopolysaccharide (LPS) of Escherichia coli O110. The following Structure of the linear tetrasaccharide O-unit of the O-polysaccharide was established by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy: Download : Download full-size image where aThr indicates allothreonine. The O-Antigen gene cluster of E. coli O110 was sequenced. The gene functions were tentatively assigned by comparison with sequences in the available databases and found to be in full agreement with the O-Antigen Structure.