Partitioning protein ParP directly links chemotaxis to biofilm dispersal in Pseudomonas aeruginosa.

Abstract

The recent characterization of partitioning proteins in the localization of chemotaxis signal transduction systems was proposed to have broad implications for polarly-flagellated non-enterobacteriaceae gamma-proteobacteria. These studies showed that the loss of either partitioning protein resulted in equivalent reductions in swimming motility and chemotaxis protein localization and inheritance. However, the role of these chemotaxis partitioning proteins outside of Vibrio spp. remains untested. Our studies on the chemotaxis partitioning proteins in Pseudomonas aeruginosa revealed an unexpected role for the partitioning protein ParP. While the P. aeruginosa ParC and ParP homologs are needed for wild type swimming motility, the loss of ParP results in a greater swimming defect compared to the parC mutant. Our studies revealed that the Par-like proteins directly interact with each other and the chemotaxis system, and ParP interacts with DipA. Deletion of dipA results in a similar defect in swimming motility as the parP mutant. ParP has an interdependence for polar cluster formation, but not localization, with both CheA and DipA, and CheA cluster formation is partially dependent on ParP. Due to the direct interactions and interdependence of cluster formation of ParP and DipA, and the similar phenotypes of the parP and dipA mutants, further investigation into the role of ParP in biofilm dispersion is warranted.\n\nImportanceImpaired chemotaxis protein cluster formation or inheritance reduces chemotaxis which can have an impact on of the virulence of a bacterium. In some gamma-proteobacteria there are systems in place to ensure that chemotaxis proteins, like chromosomes and plasmids, are localized for optimal chemotaxis and that daughter cells inherit their own clusters for use after cell division. Par-like proteins have been implicated in the partitioning and localization of chemotaxis proteins and the chemotactic ability of Vibrio spp. and Rhodobacter sphaeroides [1-3]. We propose that Par-like proteins can do more than localize chemotaxis proteins to the poles of the cells. In P. aeruginosa, they bring together other key proteins involved in regulating flagellar-based motility, and we propose they function as a critical link between biofilm dispersal and motility.