title: Structural and genetic characterization of Escherichia coli O99 antigen.
abstract: O-antigen is part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria, and contributes the major antigenic variability to the cell surface. Screening for the Escherichia coli O-serogroup is the conventional method for identifying E. coli clones. In this study, we investigated the structural characteristics of the E. coli O99 O-antigen and the organization of the genes involved in its synthesis. On the basis of sugar and methylation analysis and nuclear magnetic resonance spectroscopy data, we established the structure of the branched hexasaccharide repeat unit of the O-polysaccharide. This unit consists of four d-rhamnose (d-Rha) moieties in the backbone and two d-glucose (d-Glc) moieties in the side chain, as shown below: [carbohydrate structure: see text]. The O-antigen gene cluster of E. coli O99, which was located between galF and gnd, was found to contain putative genes for the synthesis of d-Rha, genes encoding sugar transferases, and ATP-binding cassette (ABC) transporter genes (wzm and wzt). Our findings indicate that in E. coli O99, the synthesis and translocation of the O-antigen occurs by an ABC transporter-dependent process.
authors.affiliation: N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Perepelov
authors.forename: Dan
authors.initials: D
authors.lastname: Li
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Sof'ya N
authors.initials: SN
authors.lastname: Senchenkova
authors.forename: Dan
authors.initials: D
authors.lastname: Guo
authors.forename: Sergei D
authors.initials: SD
authors.lastname: Shevelev
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
authors.forename: Xi
authors.initials: X
authors.lastname: Guo
authors.forename: Lu
authors.initials: L
authors.lastname: Feng
authors.forename: Yuriy A
authors.initials: YA
authors.lastname: Knirel
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
mesh_terms: D002240:Carbohydrate Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics; D023061:Gene Order; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D005810:Multigene Family; D019081:O Antigens / Q000737:chemistry* / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D019081:O Antigens