Enterotoxigenic Escherichia coli CS6 gene products and their roles in CS6 structural protein assembly and cellular adherence

► We constructed nonpolar css gene-deletion mutants in the ETEC background. ► Each deletion mutant showed reduced adhesion to intestinal cells. ► Only CssA-CssB-CssC complex can be recognized by usher CssD. ► CssD transports CssA-CssB to the outer membrane as a colonization factor. ► All 4 Css proteins are necessary for proper CS6 expression and cell adhesion.