Role of Vibrio polysaccharide (vps) genes in VPS production, biofilm formation and Vibrio cholerae pathogenesis

Biofilm formation enhances the survival and persistence of the facultative human pathogen Vibrio cholerae in natural ecosystems and its transmission during seasonal cholera outbreaks. A major component of the V. cholerae biofilm matrix is the Vibrio polysaccharide (VPS), which is essential for development of three-dimensional biofilm structures. The vps genes are clustered in two regions, the vps-I cluster (vpsU, vpsA-K, VC0916-27) and the vps-II cluster (vpsL-Q, VC0934-39), separated by an intergenic region containing the rbm gene cluster that encodes biofilm matrix proteins. In-frame deletions of the vps clusters and genes encoding matrix proteins drastically altered biofilm formation phenotypes. To determine which genes within the vps gene clusters are required for biofilm formation and VPS synthesis, we generated in-frame deletion mutants for all the vps genes. Many of these mutants exhibited reduced capacity to produce VPS and biofilms. Infant mouse colonization assays revealed that mutants lacking either vps clusters or rbmA (encoding secreted matrix protein RbmA) exhibited a defect in intestinal colonization compared to the wild-type. Understanding the roles of the various vps gene products will aid in the biochemical characterization of the VPS biosynthetic pathway and elucidate how vps gene products contribute to VPS biosynthesis, biofilm formation and virulence in V. cholerae.