Control of Protease Activity during Sporulation of Bacillus subtilis

Abstract

Pievious work with MAPI, a serine protease inhibitor, has shown that inactivation of membrane bound protease by MAPI resulted in inhibition of normal sporulation of Bacillus subtilis IFO 3027 [Shimizu et al., Agric. Biol Chem., 48, 365 (1984)]. In the cells cultured with MAPI, the cellular amount of IP-I, a cytoplasmic serine protease which is sensitive to EDTA was lower than the control cells. An endogenous proteinaceous inhibitor having specific inhibitory activity against IP-I was produced during the sporulation and its amount in the MAPI-treated cells was higher than that of control cells. The proteinaceous inhibitor was inactivated only by membrane bound protease. Consequently, IP-I was activated through degradation of proteinaceous inhibitor by membrane bound protease. It seems probable that the proteinaceous inhibitor and membrane bound protease are involved in the regulation of a protease system in sporulating cells of B. subtilis.