Genetic Organization of the Escherichia coli K10 Capsule Gene Cluster: Identification and Characterization of Two Conserved Regions in Group III Capsule Gene Clusters Encoding Polysaccharide Transport Functions

Analysis of the Escherichia coli K10 capsule gene cluster identified two regions, regions 1 and 3, conserved between different group III capsule gene clusters. Region 1 encodes homologues of KpsD, KpsM, KpsT, and KpsE proteins, and region 3 encodes homologues of the KpsC and KpsS proteins. An rfaH mutation abolished K10 capsule production, suggesting that expression of the K10 capsule was regulated by RfaH in a manner analogous to group II capsule gene clusters. An IS3 element and a φR73-like prophage, both of which may have played a role in the acquisition of group III capsule gene clusters, were detected flanking the K10 capsule genes.