A probable intramembrane site-2 protease (S2P) that cleaves type-2 transmembrane proteins within their membrane-spanning domains. Cleaves PbpB (PBP3, FtsI); cleavage is inhibited by Wag31-PbpB interaction. Probably also cleaves anti-sigma factors RskA, RslA and RsmA. Regulated intramembrane proteolysis (RIP) occurs when an extracytoplasmic signal (possibly oxidative stress) triggers a concerted proteolytic cascade to transmit information and elicit cellular responses. The membrane-spanning regulatory substrate protein (includes anti-sigma factors RskA, RslA, RsmA, and PbpB in M.tuberculosis) is first cut extracytoplasmically (site-1 protease, S1P), then within the membrane itself (site-2 protease, S2P, this entry), while cytoplasmic proteases finish degrading the regulatory protein, liberating the effector protein (ECF sigma factors SigK, SigL and SigM) (Probable). Not essential. Cells have altered colony morphology, lacking cording associated with virulence. Belongs to the peptidase M50B family.