Abstract
Photosynthesis produces both oxygen and reducing power, which readily react with each other to generate ROS. Previously, we have shown that treatment of Synechocystis cells with methyl viologen or H2O2 in high light induces expression of suf operon genes and suggested that Sll0088 is a transcriptional repressor (SufR) that responds to ROS. In this study, we disrupted sll0088 gene in Synechocystis and found an additional target gene by DNA microarray analysis. We overexpressed and purified its homolog Tlr0491 protein of Thermosynechococcus elongatus BP-1. It was suggested that Tlr0491 binds an iron-sulfur cluster. We coexpressed Tlr0491 with the suf genes of E. coli that facilitates biogenesis of various iron-sulfur clusters. The native Tlr0491 protein, thus obtained, showed the absorption spectrum peculiar to 2Fe-2S type. We confirmed DNA-binding affinity of Tlr0491 with various target genes and also found specific binding to a consensus sequence of the target promoters.
