Key stress-response regulator that plays an important role in multiple regulatory networks in response to different stress conditions (PubMed:20688819, PubMed:25899163). Involved in preservation of envelope integrity and tolerance to surface stress (PubMed:25899163). Essential for macrophage infection and facilitates intracellular growth of M.tuberculosis (PubMed:25899163, PubMed:20688819). Controls the expression of several protease and chaperone systems, including clpP1, clpP2, clpC1, ptrB, Rv1043c, acr2, clpB, Rv3269 and the clgR-pspA-rv2743c-rv2742c region (PubMed:20688819, PubMed:25899163, PubMed:23560081). Also plays an essential role in RecA/LexA-independent DNA repair mechanism by inducing expression of DNA repair genes in response to DNA damage (PubMed:21771781). Interacts with PspA. Expression requires SigE (PubMed:11489128, PubMed:25899163). Induced by carbonyl cyanide m-chlorophenyl hydrazone (CCCP) (PubMed:25899163). Induced in response to thioridazine (THZ) (PubMed:20386700). Inactivation of the gene increases M.tuberculosis susceptibility to the intramacrophage environment (PubMed:25899163, PubMed:20688819). Deletion mutant shows a significantly reduced ability to arrest the acidification of the phagosome (PubMed:20688819).