Analysis of orthologous hrcA genes in Escherichia coli and Bacillus subtilis.

The hrcA gene codes for a transcriptional repressor protein interacting with the CIRCE operator thereby reducing expression of the groE operon of more than 120 bacterial species. At least in Bacillus subtilis, the activity of the HrcA protein is modulated by the GroE chaperonin system. We amplified the hrcA gene from five different bacterial species and analyzed its activity in Escherichia coli and Bacillus subtilis. While those from Clostridium acetobutylicum and Staphylococcus aureus turned out to be active, those of Helicobacter pylori, Lactococcus lactis and Thermotoga maritima were inactive in E. coli, but that of T. maritima turned out to repress expression of the reporter gene in B. subtilis. All these results strongly suggest to us a specific recognition of HrcA by the GroE chaperonin system.