Regulation of hydrogenase genes by sulfur-responsive regulator, SurR, in Thermococcus onnurineus NA1

Abstract

SurR (sulfur response regulator) is a regulator which has been known to respond to elemental sulfur and to regulate hydrogenase genes in Pyrococcus furiosus. While P. furiosus contains only four hydrogenases (Mbh, Mbx, SulfI and SulfII), T. onnurineus NA1 has four more hydrogenases, Mfh1, Mfh2, Mch and Frh. T. onnurineus NA1 contains a SurR homolog and its binding site(GTTn3AAC) are conserved in the upstream region of 6 hydrogenase genes (frh, mbh, mbx, mfh2, sulfI, sulfII). To investigate the regulation of these hydrogenases by SurR, an in-frame deletion mutant of surR was constructed and the translation levels of hydrogenases were confirmed by western blotting. The regulation of expression of hydrogenases with SurR-binding sites was clearly demonstrated. Based on the expression pattern of hydrogenase genes, the role of SurR was determined as an activator or a repressor. Intriguingly, the expression pattern of sulfI and mbh in the presence of sulfur in T. onnurineus NA1 was different from that in P. furiosus. onnurineus NA1 has four more hydrogenases, Mfh1, Mfh2, Mch and Frh. T. onnurineus NA1 contains a SurR homolog and its binding site(GTTn3AAC) are conserved in the upstream region of 6 hydrogenase genes (frh, mbh, mbx, mfh2, sulfI, sulfII). To investigate the regulation of these hydrogenases by SurR, an in-frame deletion mutant of surR was constructed and the translation levels of hydrogenases were confirmed by western blotting. The regulation of expression of hydrogenases with SurR-binding sites was clearly demonstrated. Based on the expression pattern of hydrogenase genes, the role of SurR was determined as an activator or a repressor. Intriguingly, the expression pattern of sulfI and mbh in the presence of sulfur in T. onnurineus NA1 was different from that in P. furiosus.