Key stress-response regulator that plays an important role in multiple regulatory networks in response to different stress conditions (By similarity). Probably controls the response to vancomycin treatment; vancomycin induces expression of the clp regulon (clpP1, clpP2 and clpC1) (PubMed:20025669). By vancomycin, requires sigE. Depletion experiments (via anti-sense RNA) show greatly reduced induction of the clp regulon (clpP1, clpP2 and clpC1) after vancomycin treatment.