title: Genetic organization of the O7-specific lipopolysaccharide biosynthesis cluster of Escherichia coli VW187 (O7:K1).
abstract: In previous studies the authors cloned and characterized the DNA sequence of the regions at both ends of the O7-specific lipopolysaccharide (LPS) biosynthesis cluster of Escherichia coli VW187 (O7:K1), and identified the biosynthetic genes for dTDP-rhamnose and GDP-mannose, as well as one of the candidate glycosyltransferases. In this work the complete DNA sequence of a 6.9 kb intervening region is presented. Seven new ORFs were identified. All the functions required for the synthesis and transfer of the O7 LPS were assigned on the basis of complementation experiments of transposon insertion mutants, and amino acid sequence homology to proteins involved in LPS synthesis of other bacteria. Of the seven ORFs, two encoded membrane proteins that were homologous to the O-antigen translocase (Wzx) and polymerase (Wxy), two were involved in the biosynthesis of dTDP-N-acetylviosamine, and the remaining three showed homologies to sugar transferases. The O antigen chain length regulator gene wzz was also identified in the vicinity of the O7 polysaccharide cluster. O7-specific DNA primers were designed and tested for serotyping of O7 E. coli strains.
authors.affiliation: Department of Microbiology and Immunology, and Division of Clinical Microbiology, University of Western Ontario, London, Ontario, N6A 5C1, Canada1.
authors.forename: Cristina L
authors.initials: CL
authors.lastname: Marolda
authors.affiliation: Instituto de Investigaciones Bioquı́micas, Fundación Campomar, Antonio Machado 151, 1405 Buenos Aires, Argentina2.|Department of Microbiology and Immunology, and Division of Clinical Microbiology, University of Western Ontario, London, Ontario, N6A 5C1, Canada1.
authors.forename: Mario F
authors.initials: MF
authors.lastname: Feldman
authors.affiliation: Department of Microbiology and Immunology, and Division of Clinical Microbiology, University of Western Ontario, London, Ontario, N6A 5C1, Canada1.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Valvano
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002240:Carbohydrate Sequence; D002352:Carrier Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000276:immunology; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016695:Glycosyltransferases / Q000235:genetics; D006602:Hexosyltransferases / Q000235:genetics; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D016254:Mutagenesis, Insertional; D019081:O Antigens / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D016133:Polymerase Chain Reaction / Q000379:methods; D017422:Sequence Analysis, DNA; D012703:Serotyping
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D008565:Membrane Proteins; D019081:O Antigens; C117254:RfbX protein, Pseudomonas; D016695:Glycosyltransferases; D006602:Hexosyltransferases; C085652:O-antigen polymerase