Two-Component System Response Regulator ompR Regulates Mussel Settlement through Exopolysaccharides.

The outer membrane protein (OMP) is a kind of biofilm matrix component that widely exists in Gram-negative bacteria. However, the mechanism of OMP involved in the settlement of molluscs is still unclear. In this study, the mussel was selected as a model to explore the function of , a two-component system response regulator, on biofilm-forming capacity and the mussel settlement. The motility of the Δ strain was increased, the biofilm-forming capacity was decreased, and the inducing activity of the Δ biofilms in plantigrades decreased significantly ( < 0.05). The extracellular α-polysaccharide and β-polysaccharide of the Δ strain decreased by 57.27% and 62.63%, respectively. The inactivation of the gene decreased the gene expression and had no impact on expression or c-di-GMP levels. Adding recombinant OmpW protein caused the recovery of biofilm-inducing activities, accompanied by the upregulation of exopolysaccharides. The findings deepen the understanding of the regulatory mechanism of bacterial two-component systems and the settlement of benthic animals.