Structural and genetic evidence for the close relationship between Escherichia coli O71 and Salmonella enterica O28 O-antigens.
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.
Hu
Bo
B
Nankai University, Tianjin, China.
Perepelov
Andrei V
AV
Liu
Bin
B
Shevelev
Sergei D
SD
Guo
Dan
D
Senchenkova
Sof'ya N
SN
Shashkov
Alexander S
AS
Feng
Lu
L
Knirel
Yuriy A
YA
Wang
Lei
L
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
D004269:DNA, Bacterial; D019081:O Antigens