CtsR, a novel regulator of stress and heat shock response, controls clp and molecular chaperone gene expression in Gram-positive bacteria

clpP and clpC of Bacillus subtilis encode subunits of the Clp ATP-dependent protease and are required for stress survival, including growth at high te mperature!, They play essential roles in stationary phase adaptive response s such as the competence and sporulation developmental pathways, and belong to the so-called class III group of heat shock genes, whose anode of regul ation is unknown and whose expression its induced by heat shock or general stress conditions, The product of ctsR, the first gene of the clpC operon, has now been shown to act as a repressor of both clpP and clpC, as well as clpE, which encodes a novel member of the Hsp100 Clp ATPase family. The Cts R protein was purified and shown to bind specifically to the promoter regio ns of all three clp genes. Random mutagenesis, DNasel footprinting and DNA sequence deletions and comparisons were used to define a consensus CtsR rec ognition sequence as a directly repeated heptad upstream from the three clp genes, This target sequence was also found upstream from clp and other hea t shock genes of several Gram-positive bacteria, including Listeria monocyt ogenes, Streptococcus salivarius, S. pneumoniae, S. pyogenes, S. thermophil us, Enterococcus faecalis, Staphylococcus aureus, Leuconostoc oenos, Lactob acillus sake, Lactococcus lactis and Clostridium acetobutylicum. CtsR homol ogues were also identified in several of these bacteria, indicating that he at shock regulation by CtsR is highly conserved in Gram-positive bacteria.