A Second PDZ-Containing Serine Protease Contributes to Activation of the Sporulation Transcription Factor σKinBacillus subtilis

Open Access
Publisher Website
Google Scholar
Abstract
Gene expression late during the process of sporulation in Bacillus subtilis is governed by a multistep, signal transduction pathway involving the transcription factor σK, which is derived by regulated proteolysis from the inactive proprotein pro-σK. Processing of pro-σK is triggered by a signaling protein known as SpoIVB, a serine protease that contains a region with similarity to the PDZ family of protein-protein interaction domains. Here we report the discovery of a second PDZ-containing serine protease called CtpB that contributes to the activation of the pro-σK processing pathway. CtpB is a sporulation-specific, carboxyl-terminal processing protease and shares several features with SpoIVB. We propose that CtpB acts to fine-tune the regulation of pro-σK processing, and we discuss possible models by which CtpB influences the σK activation pathway.