A group of Escherichia coli and Salmonella enterica O antigens sharing a common backbone structure

Microbiology (Reading). 2007 Jul;153(Pt 7):2159-2167. doi: 10.1099/mic.0.2007/004192-0.

Abstract

The O-antigen moiety of the LPS is one of the most variable cell surface components of the Gram-negative bacterial outer membrane. Variation is due to the presence of different sugars and sugar linkages. Here, it is reported that a group of Escherichia coli O serogroups (O17, O44, O73, O77 and O106), and the Salmonella enterica serogroup O : 6,14 (H), share a common four-sugar backbone O-subunit structure, and possess almost identical O-antigen gene clusters. Whereas the E. coli O77 antigen does not have any substitutions, the other O antigens in this group differ by the addition of one or two glucose side branches at various positions of the backbone. The O-antigen gene clusters for all members of the group encode only the proteins required for biosynthesis of the common four-sugar backbone. The identification of three genes within a putative prophage in the E. coli O44 genome is also reported; these genes are presumably involved in the glucosylation of the basic tetrasaccharide unit. This was confirmed by deletion of one of the genes, which encodes a putative glucosyltransferase. Structural analysis of the O antigen produced by the mutant strain demonstrated the absence of glucosylation. An O-antigen structure shared by five E. coli and one S. enterica serogroups, all of which have a long evolutionary history, suggests that the common backbone may be important for the survival of E. coli strains in the environment, or for their pathogenicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Deoxy Sugars / analysis
  • Escherichia coli / chemistry*
  • Escherichia coli / genetics
  • Genes, Bacterial
  • Molecular Sequence Data
  • O Antigens / chemistry*
  • O Antigens / genetics*
  • Salmonella enterica / chemistry*
  • Salmonella enterica / genetics

Substances

  • Bacterial Proteins
  • Deoxy Sugars
  • O Antigens

Associated data

  • GENBANK/DQ000313
  • GENBANK/DQ000314
  • GENBANK/DQ000315