The anti-sigma factor for extracytoplasmic function (ECF) sigma factor sigma-W (SigW). Holds SigW, its cognate ECF sigma factor, in an inactive form until released by regulated intramembrane proteolysis (RIP). SigW and RsiW mediate cell response to cell wall stress (PubMed:12207695). RIP occurs when an extracytoplasmic signal triggers a concerted proteolytic cascade to transmit information and elicit cellular responses. The membrane-spanning regulatory substrate protein is first cut periplasmically (site-1 protease, S1P, PrsW) (PubMed:16816000, PubMed:17020587), then within the membrane itself (site-2 protease, S2P, RasP) (PubMed:15130127), while cytoplasmic proteases finish degrading the anti-sigma factor, liberating sigma-W (PubMed:16899079). Binds 1 Zn(2+) ion per subunit. Absence of the Zn(2+) (in a residue 1-80 fragment) does not prevent interaction with SigW, nor does it change the overall conformation of RsiW, although a disulfide bond can form between Cys-3 and Cys-37 (PubMed:28319136). Forms a heterodimer with cognate sigma factor SigW, which probably prevents SigW from binding to DNA (PubMed:28319136). Site-2 clipped RsiW is released from the membrane to the cytoplasm (PubMed:16899079). By different stresses causing damage to the cell envelope, such as alkaline shock (PubMed:11454200), salt shock (PubMed:11544224), phage infection and certain antibiotics that affect cell wall biosynthesis (PubMed:12207695, PubMed:15870467). The cytoplasmic domain is able to inactivate SigW and the extracellular and transmembrane domains are crucial for sensing and transducing the signal that triggers SigW activation (PubMed:15130127). The N-terminus binds the zinc ion and is followed by a long helix (about residues 40-80) that fits into a hydrophobic surface groove on SigW, probably blocking its ability to interact with the -10 and -35 promoter elements (PubMed:28319136). Is processed by successive proteolytic events. First, the extracellular region of RsiW is cleaved by PrsW (site-1 cleavage) in response to cell envelope stresses (PubMed:16816000, PubMed:17020587). In a reconstituted E.coli system PrsW cuts between Ala-168 and Ser-169 followed by trimming by E.coli Tsp; the endogenous extracellular exopeptidase responsible for the event in B.subtilis has not been identified (PubMed:19889088). Next, it undergoes cleavage at an intramembrane site (site-2 cleavage) mediated by RasP (PubMed:15130127). This cleavage uncovers a cryptic proteolytic tag with conserved alanine residues in the transmembrane segment, that is recognized mainly by the ClpXP protease, which completely degrades the protein in the cytoplasm and leads to the induction of the sigma-W-controlled genes (PubMed:16899079). Belongs to the zinc-associated anti-sigma factor (ZAS) superfamily. Anti-sigma-W factor family.