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Lei Wang - One of the best experts on this subject based on the ideXlab platform.

  • 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
    Journal of Bacteriology, 2011
    Co-Authors: Bin Liu, Lu Feng, Lei Wang, Yanfang Han, John S Allingham, Walter A Szarek, Inka Brockhausen
    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.

  • structural and genetic characterization of Shigella boydii type 17 o antigen and confirmation of two new genes involved in the synthesis of glucolactilic acid
    Biochemical and Biophysical Research Communications, 2006
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, A. V. Perepelov, Sergei D. Shevelev, Quan Wang, Dan Qin, Yi Ren, Lei Wang
    Abstract:

    Shigella strains are human pathogens and normally identified based on their O antigens. The chemical structure and gene cluster of Shigella boydii type 17 O antigen were studied. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen of S. boydii type 17 has a linear trisaccharide O unit, which consists of two residues of N-acetylgalactosamine (GalNAc) and a 4-O-[(R)-1-carboxyethyl]-d-glucose (glucolactilic acid). The O antigen gene cluster of S. boydii type 17 was sequenced and genes encoding UDP-N-acetylglucosamine C4 epimerase for GalNAc synthesis, O unit flippase, O antigen polymerase, and glycosyltransferases were putatively identified based on sequence similarities and the presence of conserved motifs. Two genes, whose functions could not be clearly indicated by homology search, were confirmed to be involved in the synthesis of glucolactilic acid by mutation and structural verification of the O antigens from the mutants. To our knowledge, this is the first time that genes involved in the synthesis of glucolactilic acid have been reported. Two genes specific to S. boydii type 17 were also identified.

  • Structural and genetic characterization of the Shigella boydii type 18 O antigen
    Gene, 2005
    Co-Authors: Lu Feng, Yuriy A. Knirel, Alexander S Shashkov, Sof'ya N. Senchenkova, Bin Liu, Sergei D. Shevelev, Dan Liu, Wei Wang, Lei Wang
    Abstract:

    Abstract Shigella strains are important human pathogens and are normally identified by their O antigens. O antigen is an essential part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria and plays a role in pathogenicity. Structural and genetic organization of the Shigella boydii type 18 O antigen was investigated. As judged by sugar and methylation analyses and NMR spectroscopy data, the O antigen has a linear pentasaccharide repeating unit (O unit), which consists of three l -rhamnose residues, and one residue each of d -galacturonic acid ( d -GalA) and N-acetylgalactosamine ( d -GalNAc), and the following structure of the O unit was established. →3)-β- l -Rhap-(1→4)-α- l -Rhap-(1→2)-α- l -Rhap-(1→2)-α- d -GalpA-(1→3)-α- d -GalpNAc-(1→ The O antigen gene cluster of S. boydii type 18, which contains nine open reading frames (ORFs), was found between galF and gnd. Based on homology, all of the ORFs were identified as O antigen synthesis genes, involved in the synthesis of rhamnose, transfer of sugars, and processing of O unit. Genes specific for S. boydii type 18 were identified, which can be potentially used for the development of a PCR-based assay for the identification and detection of this strain.

  • structural and genetic characterization of the Shigella boydii type 10 and type 6 o antigens
    Journal of Bacteriology, 2005
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, Peter R. Reeves, Dan Liu, Jinghua Yang, Qi Jin, Jiansong Cheng, Lei Wang
    Abstract:

    Comparison of the O antigens of Shigella boydii types 10 and 6 by chemical analysis and nuclear magnetic resonance spectroscopy showed that their structures are similar, with the only difference being the presence or absence of d-ribofuranose, which is the immunodominant sugar in S. boydii type 10. In S. boydii type 6, a residue previously reported as alpha-d-GlcpA, was shown to be beta-d-GlcpA as in S. boydii type 10. S. boydii types 10 and 6 are reported not to cross-react serologically, and the role of d-ribofuranose in the specificity of S. boydii was confirmed by making a mutant of type 10 that lacked d-ribofuranose. However, S. boydii type 11, which has a d-ribofuranose but with different linkage does show cross-reaction with type 10. The O-antigen gene loci of S. boydii types 10 and 6 were shown to be virtually identical except that orf8 (wbaM), which was confirmed as the ribofuranosyltransferase gene, is interrupted by IS629 in type 6. Therefore, it is proposed that the O-antigen gene cluster of S. boydii type 6 was derived from type 10 by an IS element insertion.

  • the o antigen gene cluster of Shigella boydii o11 and functional identification of its wzy gene
    Fems Microbiology Letters, 2004
    Co-Authors: Jiang Tao, Lu Feng, Hongjie Guo, Lei Wang
    Abstract:

    Shigella strains are human pathogens and their identification is usually based on their O-antigens. The O-antigen gene cluster of Shigella boydii O11 was sequenced. All the expected genes for the synthesis of the O-antigen were identified on the basis of homology and genes for the biosynthesis of dTDP-l-Rhamnose, genes encoding sugar transferases, as well as genes encoding O unit flippase (wzx) and O-antigen polymerase (wzy). The identity of the putative wzy gene was confirmed by showing that a wzy deficient mutant strain of S. boydii O11 produced a semi-rough LPS phenotype. The predicted wzx gene has an opposite transcription direction to that of all of the other genes in the S. boydii O11 O-antigen gene cluster. This unusual feature for the wzx gene has only previously been reported in S. boydii O6. Further comparison revealed an evolutionary relationship between O6 and O11 O-antigen gene clusters. Adjacent-gene PCR showed that Escherichia coli O105 and S. boydii O11, which share the identical O-antigen, also have the same genes and organization for their respective O-antigen gene clusters. Three genes specific for the S. boydii O11 and E. coli O105 gene clusters were identified.

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

  • Structure and genetics of the O-antigen of Escherichia coli O169 related to the O-antigen of Shigella boydii type 6.
    Carbohydrate Research, 2015
    Co-Authors: A. V. Perepelov, Alexander S Shashkov, Xi Guo, Andrei V. Filatov, Andrej Weintraub, Göran Widmalm, Yuriy A. Knirel
    Abstract:

    The O-polysaccharide (O-antigen) of Escherichia coli O169 was studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The following structure of the branched hexasaccharide repeating unit was established: [Formula: see text] The O-polysaccharide of E. coli O169 differs from that of Shigella boydii type 6 only in the presence of a side-chain glucose residue. A comparison of the O-antigen biosynthesis gene clusters between the galF to gnd genes in the genomes of the two bacteria revealed their close relationship. The glycosyltransferase gene responsible for the formation of the β-D-Glcp-(1 → 6)-α-D-Galp linkage in the O-antigen was identified in the gene cluster.

  • structural and genetic characterization of Shigella boydii type 17 o antigen and confirmation of two new genes involved in the synthesis of glucolactilic acid
    Biochemical and Biophysical Research Communications, 2006
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, A. V. Perepelov, Sergei D. Shevelev, Quan Wang, Dan Qin, Yi Ren, Lei Wang
    Abstract:

    Shigella strains are human pathogens and normally identified based on their O antigens. The chemical structure and gene cluster of Shigella boydii type 17 O antigen were studied. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen of S. boydii type 17 has a linear trisaccharide O unit, which consists of two residues of N-acetylgalactosamine (GalNAc) and a 4-O-[(R)-1-carboxyethyl]-d-glucose (glucolactilic acid). The O antigen gene cluster of S. boydii type 17 was sequenced and genes encoding UDP-N-acetylglucosamine C4 epimerase for GalNAc synthesis, O unit flippase, O antigen polymerase, and glycosyltransferases were putatively identified based on sequence similarities and the presence of conserved motifs. Two genes, whose functions could not be clearly indicated by homology search, were confirmed to be involved in the synthesis of glucolactilic acid by mutation and structural verification of the O antigens from the mutants. To our knowledge, this is the first time that genes involved in the synthesis of glucolactilic acid have been reported. Two genes specific to S. boydii type 17 were also identified.

  • Structural and molecular characterization of Shigella boydii type 16 O antigen.
    Gene, 2006
    Co-Authors: Bin Liu, Alexander S Shashkov, Lu Feng, Sof'ya N. Senchenkova, A. V. Perepelov, Sergei D. Shevelev, Yajuan Zhu, Ming Zou, Yuriy A. Knirel
    Abstract:

    Shigella is a well-known human pathogen causing dysentery and their typing is solely based on the O antigens. We investigated the chemical structure and gene cluster of Shigella boydii type 16 O antigen. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen has an O-acetylated branched pentasaccharide repeating O unit, which consists of two D-mannose residues (D-Man), one residue each of D-glucuronic acid (D-GlcA), N-acetylglucosamine (D-GlcNAc) and D-galactose (D-Gal), and the structure of the O unit was established. The O antigen gene cluster of S. boydii type 16 was identified and shown to contain putative genes for the synthesis of GDP-D-Man, genes encoding sugar transferases, O unit flippase (Wzx) and O antigen polymerase (Wzy) as expected. The function of the wzy gene was characterized by mutation test. Genes specific to S. boydii type 16 O antigen gene cluster were identified by screening 186 Escherichia coli and Shigella type strains, and can be used to develop PCR assays for detection of type 16 strains.

  • Structural and genetic characterization of the Shigella boydii type 18 O antigen
    Gene, 2005
    Co-Authors: Lu Feng, Yuriy A. Knirel, Alexander S Shashkov, Sof'ya N. Senchenkova, Bin Liu, Sergei D. Shevelev, Dan Liu, Wei Wang, Lei Wang
    Abstract:

    Abstract Shigella strains are important human pathogens and are normally identified by their O antigens. O antigen is an essential part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria and plays a role in pathogenicity. Structural and genetic organization of the Shigella boydii type 18 O antigen was investigated. As judged by sugar and methylation analyses and NMR spectroscopy data, the O antigen has a linear pentasaccharide repeating unit (O unit), which consists of three l -rhamnose residues, and one residue each of d -galacturonic acid ( d -GalA) and N-acetylgalactosamine ( d -GalNAc), and the following structure of the O unit was established. →3)-β- l -Rhap-(1→4)-α- l -Rhap-(1→2)-α- l -Rhap-(1→2)-α- d -GalpA-(1→3)-α- d -GalpNAc-(1→ The O antigen gene cluster of S. boydii type 18, which contains nine open reading frames (ORFs), was found between galF and gnd. Based on homology, all of the ORFs were identified as O antigen synthesis genes, involved in the synthesis of rhamnose, transfer of sugars, and processing of O unit. Genes specific for S. boydii type 18 were identified, which can be potentially used for the development of a PCR-based assay for the identification and detection of this strain.

  • structural and genetic characterization of the Shigella boydii type 10 and type 6 o antigens
    Journal of Bacteriology, 2005
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, Peter R. Reeves, Dan Liu, Jinghua Yang, Qi Jin, Jiansong Cheng, Lei Wang
    Abstract:

    Comparison of the O antigens of Shigella boydii types 10 and 6 by chemical analysis and nuclear magnetic resonance spectroscopy showed that their structures are similar, with the only difference being the presence or absence of d-ribofuranose, which is the immunodominant sugar in S. boydii type 10. In S. boydii type 6, a residue previously reported as alpha-d-GlcpA, was shown to be beta-d-GlcpA as in S. boydii type 10. S. boydii types 10 and 6 are reported not to cross-react serologically, and the role of d-ribofuranose in the specificity of S. boydii was confirmed by making a mutant of type 10 that lacked d-ribofuranose. However, S. boydii type 11, which has a d-ribofuranose but with different linkage does show cross-reaction with type 10. The O-antigen gene loci of S. boydii types 10 and 6 were shown to be virtually identical except that orf8 (wbaM), which was confirmed as the ribofuranosyltransferase gene, is interrupted by IS629 in type 6. Therefore, it is proposed that the O-antigen gene cluster of S. boydii type 6 was derived from type 10 by an IS element insertion.

Lu Feng - One of the best experts on this subject based on the ideXlab platform.

  • 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
    Journal of Bacteriology, 2011
    Co-Authors: Bin Liu, Lu Feng, Lei Wang, Yanfang Han, John S Allingham, Walter A Szarek, Inka Brockhausen
    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.

  • structural and genetic characterization of Shigella boydii type 17 o antigen and confirmation of two new genes involved in the synthesis of glucolactilic acid
    Biochemical and Biophysical Research Communications, 2006
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, A. V. Perepelov, Sergei D. Shevelev, Quan Wang, Dan Qin, Yi Ren, Lei Wang
    Abstract:

    Shigella strains are human pathogens and normally identified based on their O antigens. The chemical structure and gene cluster of Shigella boydii type 17 O antigen were studied. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen of S. boydii type 17 has a linear trisaccharide O unit, which consists of two residues of N-acetylgalactosamine (GalNAc) and a 4-O-[(R)-1-carboxyethyl]-d-glucose (glucolactilic acid). The O antigen gene cluster of S. boydii type 17 was sequenced and genes encoding UDP-N-acetylglucosamine C4 epimerase for GalNAc synthesis, O unit flippase, O antigen polymerase, and glycosyltransferases were putatively identified based on sequence similarities and the presence of conserved motifs. Two genes, whose functions could not be clearly indicated by homology search, were confirmed to be involved in the synthesis of glucolactilic acid by mutation and structural verification of the O antigens from the mutants. To our knowledge, this is the first time that genes involved in the synthesis of glucolactilic acid have been reported. Two genes specific to S. boydii type 17 were also identified.

  • Structural and molecular characterization of Shigella boydii type 16 O antigen.
    Gene, 2006
    Co-Authors: Bin Liu, Alexander S Shashkov, Lu Feng, Sof'ya N. Senchenkova, A. V. Perepelov, Sergei D. Shevelev, Yajuan Zhu, Ming Zou, Yuriy A. Knirel
    Abstract:

    Shigella is a well-known human pathogen causing dysentery and their typing is solely based on the O antigens. We investigated the chemical structure and gene cluster of Shigella boydii type 16 O antigen. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen has an O-acetylated branched pentasaccharide repeating O unit, which consists of two D-mannose residues (D-Man), one residue each of D-glucuronic acid (D-GlcA), N-acetylglucosamine (D-GlcNAc) and D-galactose (D-Gal), and the structure of the O unit was established. The O antigen gene cluster of S. boydii type 16 was identified and shown to contain putative genes for the synthesis of GDP-D-Man, genes encoding sugar transferases, O unit flippase (Wzx) and O antigen polymerase (Wzy) as expected. The function of the wzy gene was characterized by mutation test. Genes specific to S. boydii type 16 O antigen gene cluster were identified by screening 186 Escherichia coli and Shigella type strains, and can be used to develop PCR assays for detection of type 16 strains.

  • Structural and genetic characterization of the Shigella boydii type 18 O antigen
    Gene, 2005
    Co-Authors: Lu Feng, Yuriy A. Knirel, Alexander S Shashkov, Sof'ya N. Senchenkova, Bin Liu, Sergei D. Shevelev, Dan Liu, Wei Wang, Lei Wang
    Abstract:

    Abstract Shigella strains are important human pathogens and are normally identified by their O antigens. O antigen is an essential part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria and plays a role in pathogenicity. Structural and genetic organization of the Shigella boydii type 18 O antigen was investigated. As judged by sugar and methylation analyses and NMR spectroscopy data, the O antigen has a linear pentasaccharide repeating unit (O unit), which consists of three l -rhamnose residues, and one residue each of d -galacturonic acid ( d -GalA) and N-acetylgalactosamine ( d -GalNAc), and the following structure of the O unit was established. →3)-β- l -Rhap-(1→4)-α- l -Rhap-(1→2)-α- l -Rhap-(1→2)-α- d -GalpA-(1→3)-α- d -GalpNAc-(1→ The O antigen gene cluster of S. boydii type 18, which contains nine open reading frames (ORFs), was found between galF and gnd. Based on homology, all of the ORFs were identified as O antigen synthesis genes, involved in the synthesis of rhamnose, transfer of sugars, and processing of O unit. Genes specific for S. boydii type 18 were identified, which can be potentially used for the development of a PCR-based assay for the identification and detection of this strain.

  • structural and genetic characterization of the Shigella boydii type 10 and type 6 o antigens
    Journal of Bacteriology, 2005
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, Peter R. Reeves, Dan Liu, Jinghua Yang, Qi Jin, Jiansong Cheng, Lei Wang
    Abstract:

    Comparison of the O antigens of Shigella boydii types 10 and 6 by chemical analysis and nuclear magnetic resonance spectroscopy showed that their structures are similar, with the only difference being the presence or absence of d-ribofuranose, which is the immunodominant sugar in S. boydii type 10. In S. boydii type 6, a residue previously reported as alpha-d-GlcpA, was shown to be beta-d-GlcpA as in S. boydii type 10. S. boydii types 10 and 6 are reported not to cross-react serologically, and the role of d-ribofuranose in the specificity of S. boydii was confirmed by making a mutant of type 10 that lacked d-ribofuranose. However, S. boydii type 11, which has a d-ribofuranose but with different linkage does show cross-reaction with type 10. The O-antigen gene loci of S. boydii types 10 and 6 were shown to be virtually identical except that orf8 (wbaM), which was confirmed as the ribofuranosyltransferase gene, is interrupted by IS629 in type 6. Therefore, it is proposed that the O-antigen gene cluster of S. boydii type 6 was derived from type 10 by an IS element insertion.

Sof'ya N. Senchenkova - One of the best experts on this subject based on the ideXlab platform.

  • structural and genetic characterization of Shigella boydii type 17 o antigen and confirmation of two new genes involved in the synthesis of glucolactilic acid
    Biochemical and Biophysical Research Communications, 2006
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, A. V. Perepelov, Sergei D. Shevelev, Quan Wang, Dan Qin, Yi Ren, Lei Wang
    Abstract:

    Shigella strains are human pathogens and normally identified based on their O antigens. The chemical structure and gene cluster of Shigella boydii type 17 O antigen were studied. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen of S. boydii type 17 has a linear trisaccharide O unit, which consists of two residues of N-acetylgalactosamine (GalNAc) and a 4-O-[(R)-1-carboxyethyl]-d-glucose (glucolactilic acid). The O antigen gene cluster of S. boydii type 17 was sequenced and genes encoding UDP-N-acetylglucosamine C4 epimerase for GalNAc synthesis, O unit flippase, O antigen polymerase, and glycosyltransferases were putatively identified based on sequence similarities and the presence of conserved motifs. Two genes, whose functions could not be clearly indicated by homology search, were confirmed to be involved in the synthesis of glucolactilic acid by mutation and structural verification of the O antigens from the mutants. To our knowledge, this is the first time that genes involved in the synthesis of glucolactilic acid have been reported. Two genes specific to S. boydii type 17 were also identified.

  • Structural and molecular characterization of Shigella boydii type 16 O antigen.
    Gene, 2006
    Co-Authors: Bin Liu, Alexander S Shashkov, Lu Feng, Sof'ya N. Senchenkova, A. V. Perepelov, Sergei D. Shevelev, Yajuan Zhu, Ming Zou, Yuriy A. Knirel
    Abstract:

    Shigella is a well-known human pathogen causing dysentery and their typing is solely based on the O antigens. We investigated the chemical structure and gene cluster of Shigella boydii type 16 O antigen. As judged by sugar and methylation analyses along with NMR spectroscopy data, the O antigen has an O-acetylated branched pentasaccharide repeating O unit, which consists of two D-mannose residues (D-Man), one residue each of D-glucuronic acid (D-GlcA), N-acetylglucosamine (D-GlcNAc) and D-galactose (D-Gal), and the structure of the O unit was established. The O antigen gene cluster of S. boydii type 16 was identified and shown to contain putative genes for the synthesis of GDP-D-Man, genes encoding sugar transferases, O unit flippase (Wzx) and O antigen polymerase (Wzy) as expected. The function of the wzy gene was characterized by mutation test. Genes specific to S. boydii type 16 O antigen gene cluster were identified by screening 186 Escherichia coli and Shigella type strains, and can be used to develop PCR assays for detection of type 16 strains.

  • Structural and genetic characterization of the Shigella boydii type 18 O antigen
    Gene, 2005
    Co-Authors: Lu Feng, Yuriy A. Knirel, Alexander S Shashkov, Sof'ya N. Senchenkova, Bin Liu, Sergei D. Shevelev, Dan Liu, Wei Wang, Lei Wang
    Abstract:

    Abstract Shigella strains are important human pathogens and are normally identified by their O antigens. O antigen is an essential part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria and plays a role in pathogenicity. Structural and genetic organization of the Shigella boydii type 18 O antigen was investigated. As judged by sugar and methylation analyses and NMR spectroscopy data, the O antigen has a linear pentasaccharide repeating unit (O unit), which consists of three l -rhamnose residues, and one residue each of d -galacturonic acid ( d -GalA) and N-acetylgalactosamine ( d -GalNAc), and the following structure of the O unit was established. →3)-β- l -Rhap-(1→4)-α- l -Rhap-(1→2)-α- l -Rhap-(1→2)-α- d -GalpA-(1→3)-α- d -GalpNAc-(1→ The O antigen gene cluster of S. boydii type 18, which contains nine open reading frames (ORFs), was found between galF and gnd. Based on homology, all of the ORFs were identified as O antigen synthesis genes, involved in the synthesis of rhamnose, transfer of sugars, and processing of O unit. Genes specific for S. boydii type 18 were identified, which can be potentially used for the development of a PCR-based assay for the identification and detection of this strain.

  • structural and genetic characterization of the Shigella boydii type 10 and type 6 o antigens
    Journal of Bacteriology, 2005
    Co-Authors: Sof'ya N. Senchenkova, Yuriy A. Knirel, Alexander S Shashkov, Lu Feng, Peter R. Reeves, Dan Liu, Jinghua Yang, Qi Jin, Jiansong Cheng, Lei Wang
    Abstract:

    Comparison of the O antigens of Shigella boydii types 10 and 6 by chemical analysis and nuclear magnetic resonance spectroscopy showed that their structures are similar, with the only difference being the presence or absence of d-ribofuranose, which is the immunodominant sugar in S. boydii type 10. In S. boydii type 6, a residue previously reported as alpha-d-GlcpA, was shown to be beta-d-GlcpA as in S. boydii type 10. S. boydii types 10 and 6 are reported not to cross-react serologically, and the role of d-ribofuranose in the specificity of S. boydii was confirmed by making a mutant of type 10 that lacked d-ribofuranose. However, S. boydii type 11, which has a d-ribofuranose but with different linkage does show cross-reaction with type 10. The O-antigen gene loci of S. boydii types 10 and 6 were shown to be virtually identical except that orf8 (wbaM), which was confirmed as the ribofuranosyltransferase gene, is interrupted by IS629 in type 6. Therefore, it is proposed that the O-antigen gene cluster of S. boydii type 6 was derived from type 10 by an IS element insertion.

  • structural and genetic characterization of the Shigella boydii type 13 o antigen
    Journal of Bacteriology, 2004
    Co-Authors: Lu Feng, Yuriy A. Knirel, Alexander S Shashkov, Sof'ya N. Senchenkova, Peter R. Reeves, Guang Zhao, Jinghua Yang, Jiang Tao, Hongjie Guo, Lei Wang
    Abstract:

    Shigella is an important human pathogen. It is generally agreed that Shigella and Escherichia coli constitute a single species; the only exception is Shigella boydii type 13, which is more distantly related to E. coli and other Shigella forms and seems to represent another species. This gives S. boydii type 13 an important status in evolution. O antigen is the polysaccharide part of the lipopolysaccharide in the outer membrane of gram-negative bacteria and plays an important role in pathogenicity. The chemical structure and genetic organization of the S. boydii type 13 O antigen were investigated. The O polysaccharide was found to be acid labile owing to the presence of a glycosyl phosphate linkage in the main chain. The structure of the linear pentasaccharide phosphate repeating unit (O unit) was established by nuclear magnetic resonance spectroscopy, including two-dimensional COSY, TOCSY, ROESY, and H-detected 1H,13C and 1H,31P HMQC experiments, along with chemical methods. The O antigen gene cluster of S. boydii type 13 was located and sequenced. Genes for synthesis of UDP-2-acetamido-2,6-dideoxy-l-glucose and genes that encode putative sugar transferases, O unit flippase, and O antigen polymerase were identified. Seven genes were found to be specific to S. boydii type 13. The S. boydii type 13 O antigen gene cluster has higher levels of sequence similarity with Vibrio cholerae gene clusters and may be evolutionarily related to these gene clusters.

Anup Kumar Misra - One of the best experts on this subject based on the ideXlab platform.

  • straightforward sequential and one pot synthesis of a pentasaccharide repeating unit corresponding to the cell wall o antigen of Shigella boydii type 18
    Tetrahedron, 2019
    Co-Authors: Pradip Shit, Arin Gucchait, Anup Kumar Misra
    Abstract:

    Abstract Synthesis of a pentasaccharide repeating unit corresponding to the cell of wall O-antigen Shigella boydii type 18 has been achieved by sequential as well as iterative glycosylations in one-pot. Use of p-methoxybenzyl group (PMB) as an in situ removable protecting group allowed obtaining the desired pentasaccharide derivative in a generalized glycosylation condition and in one-pot condition. Synthesis of a beta-L-rhamnosidic linkage present in the molecule has been successfully achieved using l -rhamnosyl thioglycoside donor having a picoloyl group at remote C-3 position influencing beta selectivity in the glycosylation. A combination of N-iodosuccinimide (NIS) and perchloric acid supported over silica (HClO4–SiO2) has been used as thiophilic glycosylation promoter in all glycosylation reactions. TEMPO mediated selective oxidation of the primary hydroxyl group has been carried out at the late stage of the synthetic strategy.

  • Convergent synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9
    Beilstein journal of organic chemistry, 2011
    Co-Authors: Abhishek Santra, Anup Kumar Misra
    Abstract:

    A convenient synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9 has been achieved in excellent yield using a [2 + 2] block glycosylation strategy. TEMPO-mediated selective oxidation of the primary alcohol of the tetrasaccharide derivative 8 to the carboxylic group followed by deprotection of the functional groups furnished target tetrasaccharide 1 as its 4-methoxyphenyl glycoside in high yield.

  • convergent synthesis of the pentasaccharide repeating unit of the o antigen of Shigella boydii type 14
    Tetrahedron-asymmetry, 2011
    Co-Authors: Rajib Panchadhayee, Anup Kumar Misra
    Abstract:

    Abstract An efficient synthesis of the pentasaccharide repeating unit of the O-antigen of Shigella boydii type 14 is reported. A one-pot, two step iterative glycosylation and [3+2] block synthetic strategy have been adopted for the construction of the pentasaccharide derivative 11 , which was then transformed into target compound 1 after a series of functional group transformations. The primary hydroxyl group has been selectively oxidized to a carboxylic acid functionality without affecting the secondary hydroxyl groups. HClO 4 –SiO 2 has been used as a solid acid substitute in all glycosylation and functional group transformations. The yields were excellent in all glycosylation steps.

  • Synthesis of tri- and pentasaccharide fragments corresponding to the O-antigen of Shigella boydii type 6
    Tetrahedron-asymmetry, 2010
    Co-Authors: Abhishek Santra, Anup Kumar Misra
    Abstract:

    Abstract A convenient synthetic strategy for the synthesis of the acidic pentasaccharide repeating unit and its trisaccharide fragment corresponding to the O-antigen of Shigella boydii type 6 has been successfully developed. A stereoselective sequential glycosylation method has been exploited to obtain the target tri- and pentasaccharide derivatives. Most of the synthetic intermediates were solid and prepared in high yields from commercially available reducing sugars following a series of protection–deprotection reactions. A late-stage TEMPO mediated selective oxidation reaction finally resulted in the pentasaccharide containing a glucuronic acid unit. A 2-(4-methoxyphenoxy) ethyl group has been chosen as the anomeric protecting group to provide trisaccharide and pentasaccharide derivatives linked to an ethylene glycol linker.