Structural Basis for the Differential Regulatory Roles of the PDZ Domain in C-Terminal Processing Proteases.

Carboxyl (C)-terminal processing proteases (CTPs) participate in protective and regulatory proteolysis in bacteria. The PDZ domain is central to the activity of CTPs but plays inherently different regulatory roles. For example, the PDZ domain inhibits the activity of the signaling protease CtpB by blocking the active site but is required for the activation of Prc (or Tsp), a tail-specific protease that degrades SsrA-tagged proteins.