Abstract
Photosynthetic organisms, such as cyanobacteria, must be able to respond to oxidative stress. We have reported several transcriptional regulators such as an oxidant-inducible PerR-like transcriptional regulator Slr1738 and ROS-inducible transcriptional regulator SufR. In the course of microarray screening of Synechocystis sp. PCC 6803, we found that genes from sll1158 to sll1161 were strongly induced by hydrogen peroxide stress under the high light conditions. On the Synechocystis genome, a LysR-type transcriptional regulator, Slr1245, is located immediately upstream of the sll1158 gene in the divergent direction. The Δslr1245 mutant did not induce the genes from sll1158 to sll1161 upon the hydrogen peroxide stress. Gel shift assay confirmed that the Slr1245 protein bound to an upstream promoter region of sll1158. These results suggest that Slr1245 is the hydrogen peroxide-responsive transcriptional activator to induce expression of the genes from sll1158 to sll1161. Further studies are being done to know the physiological role of these genes and the hydrogen-peroxide-sensing mechanism of Slr1245.
