Evolutionary origins and sequence of the Escherichia coli O4O-antigen gene cluster

Escherichia coli express many types of O antigen, present in the outer membrane of the Gram-negative bacterial cell wall. O-Antigen biosynthesis genes are clustered together and differences seen in O-antigen types are due to genetic variation within this gene cluster. Sequencing of the E coli O4 O-antigen gene cluster revealed a similar gene order and high levels of similarity to that of E coli O26; indicating a common ancestor. These lateral transfer events observed within O-antigen gene clusters may occur as part of the evolution of the pathogenic clones. (C) 2005 Published by Elsevier B.V. on behalf of the Federation of European Microbiological Societies.