title: Structural and genetic evidence for the close relationship between Escherichia coli O71 and Salmonella enterica O28 O-antigens.
abstract: O-antigen is the most variable cell wall constituent of Gram-negative bacteria. Escherichia coli and Salmonella enterica are closely related species. In this work, we present structural and genetic evidence for the close relationship between O-antigens of E. coli O71 and S. enterica O28. The E. coli O71 O-antigen was found to consist of tetrasaccharide-repeating units containing d-GalpNAc, d-Galp, l-Rhap, and d-Quip3NAc, with multiple O-acetyl lateral groups. It is very similar to the known structure of the S. enterica O28 O-antigen, which has the same backbone units, but with a lateral Glc residue instead of O-acetyl groups. The O-antigen gene clusters of E. coli O71 and S. enterica O28 were sequenced and found to contain the same genes with high-level similarity. All of the genes expected for the synthesis of the common backbone structure of the two O-antigens were identified based on homology. It is proposed that the two gene clusters had originated from the same ancestor, and diverged by acquiring prophage genes to carry out side-chain modifications. This is a new pair of the closely related E. coli and S. enterica O-serogroups. The serogroup-specific genes of E. coli O71 and S. enterica O28 were also identified.
authors.affiliation: Nankai University, Tianjin, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Hu
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Perepelov
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Sergei D
authors.initials: SD
authors.lastname: Shevelev
authors.forename: Dan
authors.initials: D
authors.lastname: Guo
authors.forename: Sof'ya N
authors.initials: SN
authors.lastname: Senchenkova
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Shashkov
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 / Q000276:immunology*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D005810:Multigene Family; D019081:O Antigens / Q000737:chemistry* / Q000235:genetics*; D019779:Salmonella enterica / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D026801:Synteny
chemical_list: D004269:DNA, Bacterial; D019081:O Antigens