Involved in the degradation of anti-sigma-W factor RsiW. Responsible for Site-1 cleavage of the RsiW anti-sigma factor. This results, after two other proteolytic steps catalyzed by the RasP and ClpXP proteases, in the release of SigW and the transcription activation of the genes under the control of the sigma-W factor. Seems to be responsible for sensing antimicrobial peptides that damage the cell membrane and other agents that cause cell envelope stress. Therefore it is a protease governing regulated intramembrane proteolysis and resistance to antimicrobial peptides in B.subtilis. Loss of expression of the SigW regulon (PubMed:17020587). Belongs to the protease PrsW family.