Function, localization and regulation of the Pseudomonas aeruginosa diguanylate cyclase response regulator WspR

Abstract

WspR is a hybrid response regulator-diguanylate cyclase that is phosphorylated by the Wsp signal transduction complex in response to growth of <italic>Pseudomonas aeruginosa</italic> on surfaces. Active WspR produces c-di-GMP, which in turn stimulates biofilm formation. Previous work demonstrated that when phosphorylated in response to growth on surfaces, WspR has a tendency to form oligomers that are visible in cells as subcellular clusters. In this study, I sought to determine the physiological relevance of WspR and its subcellular clustering, as well as the mechanism of how WspR forms subcellular clusters. My results confirm that WspR contributes specifically to production of the Pel polysaccharide. Cluster formation appears to be an intrinsic property of WspR. Analysis of six single amino acid variants of WspR show that the formation of WspR-P subcellular clusters is important for potentiating the diguanylate cyclase activity of WspR, making it more active in c-di-GMP production. Finally, I observed that c-di-GMP inhibition may play a role in the subcellular cluster formation of WspR. Oligomer formation visualized as subcellular clusters is a mechanism by which the activities of response regulator-diguanylate cyclases can be regulated. This work includes a supplementary movie depicting the movement of WspR subcellular clusters in a 5 s time frame.