It was recently found that one ECF sigma factor, SigV, in Bacillus subtilis is induced by lysozyme stress. Activity of SigV is inhibited by a membrane bound anti-sigma factor RsiV. Many ECF sigma factors are activated by two successive proteolytic events known as site 1 and site 2 cleavage of the anti-sigma factor in response to antimicrobial peptides and other agents that damage the cell envelope. These two sites are cleaved by specific proteases that function to destroy the anti-sigma factor. Site 2 cleavage of the anti-sigma factor, RsiV , is achieved by a protease called rasP/YluC , but the protease responsible for site 1 cleavage remains unknown. We presume that there is a site 1 where regulation occurs because generally site 2 cleavage occurs as a passive consequence of the first cleavage event. In order to find out about this site 1 protease we have performed transposon mutagenesis to look for mutants that don't turn on sigV in response to lysozyme stress and find genes that are required for activation of sigV.