Structural and genetic evidence for the close relationship between Escherichia coli O71 and Salmonella enterica O28 O-antigens

• Published in: FEMS immunology and medical microbiology 2010-07, Vol.59 (2), p.161-169
• Main Authors: Hu, Bo, Perepelov, Andrei V., Liu, Bin, Shevelev, Sergei D., Guo, Dan, Senchenkova, Sof'ya N., Shashkov, Alexander S., Feng, Lu, Knirel, Yuriy A., Wang, Lei
• Format: Article
• Language: English
• Subjects: Antigens; Backbone; Bacteria; Carbohydrate Sequence; Cell walls; Coliforms; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; E coli; Escherichia coli; Escherichia coli - chemistry; Escherichia coli - genetics; Escherichia coli - immunology; Gene clusters; Genes; Gram-negative bacteria; Homology; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Multigene Family; O Antigens - chemistry; O Antigens - genetics; O‐antigen gene cluster; O‐antigen structure; PCR assay; Salmonella; Salmonella enterica; Salmonella enterica - chemistry; Salmonella enterica - genetics; Salmonella enterica - immunology; Sequence Analysis, DNA; Sequence Homology; Synteny
• ISSN: 0928-8244; 1574-695X; 2049-632X
• DOI: 10.1111/j.1574-695X.2010.00676.x

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.