1887

Abstract

Bacteria undergo a complex programme of differential gene expression in response to stress. In , it was recently shown that CtsR, a negative transcriptional regulator, mediates stress-induced expression of components of the Clp protease complex. In this study, a gene was identified in the Gram-positive bacterium that encodes a 17 kDa product with 38% identity to the CtsR protein of . By Northern analyses it was found that in a strain carrying a large internal deletion of , including the region encoding a putative helix–turn–helix motif, the amounts of , , and mRNAs were increased 3–8-fold compared to those present in wild-type MG1363. In another mutant strain in which only one-third of CtsR was deleted, leaving the putative DNA-binding domain and the C-terminal 29 amino acids intact, only minor derepression of gene expression was observed and, furthermore, all the genes were still induced by heat. These results indicate that the amino acids of CtsR involved in temperature sensing are located either close to the DNA-binding domain or in the C-terminal part of the protein. Thus, in in addition to , CtsR is a key regulator of heat-shock-induced gene expression, suggesting that the presence of CtsR-homologous DNA-binding sites observed in many Gram-positive bacteria reflects functional heat-shock regulatory systems.

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2000-06-01
2019-10-17
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