Structural and functional studies on an FtsH inhibitor from Bacillus subtilis

The small 3 kDa SpoVM protein is essential for development of the spore in Bacillus subtilis. Genetic and biochemical experiments have shown that the function of SpoVM is to inhibit the proteolytic activity of FtsH during spo rulation. We have used a combination of genetic and biophysical techniques to characterise the role of this small polypeptide. SpoVM was found to be w idespread in Bacillus as well as in two Clostridia species, suggesting that SpoVM provides a common mechanism for inactivating the FtsH protease durin g spore differentiation. Using site-specific mutagenesis, we have identifie d C-terminal residues of SpoVM essential for biological activity. Analysis of SpoVM's structure showed that it is able to assume an a-helical conforma tion in the presence of a lipid interface which may be important in interac ting with FtsH. (C) 2000 Elsevier Science B.V. All rights reserved.