Stress induction of clpC in Bacillus subtilis and its involvement in stress tolerance.

A member of the clpC subfamily of stress response-related Clp ATPases was cloned from Bacillus subtilis. The B. subtilis clpC gene was induced in response to various stresses, including heat shock. Its product was identified as a general stress protein (Gsp12) described previously. A dramatic increase in the amount of clpC mRNA immediately after exposure to multiple stresses suggested regulation on a transcriptional level. Induction by heat shock was independent of the alternative sigma factor SigB, indicating a new mechanism of heat shock induction in B. subtilis. A clpC insertional mutant had an impaired tolerance for heat shock and salt stress. Furthermore, the mutation triggered the formation of elongated cells, a phenomenon particularly pronounced during stress.