transmembrane subunit that binds and oxidizes menaquinol. The transfer of an e- from menaquinol to the 4Fe:4S clusters and finally to the pterin-Mo active site generates a proton gradient used for ATP generation. DMSOR regulated predominantly at a transcriptional level. It is encoded by the dor gene and expressed when activated by a signal cascade, which is under the regulation of DorS, DorR, and DorC proteins. A study of lacZ fusions (reporter genes) to corresponding dorS, dorR, and dorC promoters concluded that expression of DorR and DorC increased in reduced oxygen environments, but DorS expression was unaffected by oxygen concentration. DorC expression also increased with increasing concentrations of DMSO. Environmental impact DMS, a product of DMSOR, is a component of the sulfur cycle. DMS is oxidized to Methanesulfonates, which nucleate cloud condensation over open oceans, where the alternative source of nucleation, dust, is absent. Cloud formation is a key component in increasing earth's albedo and regulating atmospheric temperature, thus this enzyme and the reaction it catalyzes could prove helpful on the climate control frontier. References Oxidoreductases EC 1.8.5