Regulatory role of transcription factor SutR (YdcN) in sulfur utilization in Escherichia coli.

Sulfur makes up 1 % of the dry mass of bacteria, and it is an abundant element (0.1 %) on earth. Sulfur in the environment is, however, mostly in oxidized forms and inaccessible to living organisms. At present, the entire assimilation pathway of external sulfur to sulfur-containing biomolecules and its regulation in Escherichia coli remain poorly understood, except for the metabolic pathway of cysteine synthesis, the first-step metabolite of sulfur assembly. During the search for regulation targets of uncharacterized transcription factors by Genomic SELEX screening, we found that the hitherto uncharacterized YdcN regulates a set of genes involved in the utilization of sulfur, including the generation of sulfate and its reduction, the synthesis of cysteine, the synthesis of enzymes containing Fe-S as cofactors, and the modification of tRNA with use of sulfur-containing substrates. Taking these findings together, we propose renaming YdcN as SutR (regulator of sulfur utilization).