Role of the Two Adaptor Proteins in the Chp Chemosensory System of Pseudomonas Aeruginosa

Abstract

The Chp chemosensory system in Pseudomonas aeruginosa controls two outputs: twitching motility (surface-mediated movement via Type IV pili) and intracellular adenosine 3’, 5’-cyclic monophosphate (cAMP) levels (by modulating the activity of major adenylate cyclase CyaB). This study was done to investigate the roles of the two adaptor proteins, PilI and ChpC in connecting one methyl-accepting protein (MCP) to one histidine kinase. We assayed -galactosidase activity as an indicator of the relative levels of intracellular cAMP and measured twitching motility. We also studied the interaction of the adaptor proteins within the Chp chemosensory system. Our bacterial adenylate cyclase two-hybrid analysis showed that PilI and ChpC interacted with each other, but did not show interaction with themselves or with the MCP. Both adaptor proteins were required for the proper functioning of the system. However, PilI played a much bigger role than ChpC in regulating both twitching motility and cAMP levels.