Abstract
In the Synechocystis sp. PCC 6803 genome, an ORF encoding a HrcA homolog is present and the DNA element CIRCE has been identified around the transcriptional start site of the two groEL genes, groEL1 and groEL2, suggesting that the groEL genes are controlled by the CIRCE/HrcA system. The HrcA repressor interacts with CIRCE and controls eubacterial dnaK and/or groEL operons.
We inactivated the hrcA gene in Synechocystis sp. PCC 6803. In the hrcA mutant, the groEL genes were derepressed at 30oC. But their expressions were not fully derepressed, suggesting that another level of heat shock control exists.
The inactivation of the hrcA gene did not affect the expression of other heat shock genes such as clpB, htpG, dnaK, hspA at a normal growth temperature. However, some change in the heat shock response of these genes was brought about by the mutation.
