Figure 2. Model of lysozyme-mediated σ^V activation.

A. In the absence of lysozyme, RsiV (red) binds σ^V (green). Two amphipathic helices of RsiV (short red cylinders) are embedded in the membrane. B. Lysozyme (blue ribbon diagram) binds the C-terminal extracytoplasmic portion of RsiV (red ribbon diagram) and alters the structure of RsiV such that the amphipathic helices are no longer membrane-embedded. C. Signal peptidase (grey) can recognize and cleave RsiV at site-1 within the first amphipathic helix. D. The site-2 protease (RasP/Eep in purple) cleaves the site-1 cleavage product within the transmembrane domain. E. Cytoplasmic proteases (light blue) further degrade the RsiV site-2 cleavage product. F. σ^V (green), no longer bound to RsiV, is free to interact with RNA polymerase and σ^V promoters.