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

Abstract

Biofilm formation enhances the survival and persistence of the facultative human pathogenVibrio choleraein natural ecosystems and its transmission during seasonal cholera outbreaks. A major component of theV. choleraebiofilm matrix is theVibriopolysaccharide (VPS), which is essential for development of three-dimensional biofilm structures. Thevpsgenes are clustered in two regions, thevps-I cluster (vpsU,vpsA–K, VC0916–27) and thevps-II cluster (vpsL–Q, VC0934–39), separated by an intergenic region containing therbmgene cluster that encodes biofilm matrix proteins. In-frame deletions of thevpsclusters and genes encoding matrix proteins drastically altered biofilm formation phenotypes. To determine which genes within thevpsgene clusters are required for biofilm formation and VPS synthesis, we generated in-frame deletion mutants for all thevpsgenes. Many of these mutants exhibited reduced capacity to produce VPS and biofilms. Infant mouse colonization assays revealed that mutants lacking eithervpsclusters orrbmA(encoding secreted matrix protein RbmA) exhibited a defect in intestinal colonization compared to the wild-type. Understanding the roles of the variousvpsgene products will aid in the biochemical characterization of the VPS biosynthetic pathway and elucidate howvpsgene products contribute to VPS biosynthesis, biofilm formation and virulence inV. cholerae.