Abstract
At levels of 10μg/ml (≈ 10-5 m), MAPI, a peptidealdehyde type serine protease inhibitor, selectively inhibited sporulation of B. subtilis without appreciably altering exponential growth. The strongest inhibition ofsporulation is observed when the inhibitor is added within the first 3-4 hr of sporulation.
Using [14C]MAPI, the existence of an MAPI-binding substance was investigated. More than 50%of the incorporated MAPIformed a complex with a constituent of the membrane. This substance was identified as the membrane bound protease [Shimizu et al., Agric. Biol Chem., 47, 1 775 (1 983)] from chromatographic and enzymatic properties. These results strongly suggested that the inhibition of sporulation of MAPImay be due to repression of proteolytic activity of the membranebound enzyme through the complex formation. They also suggested that all the essential function of the enzymewas complete before t4.
