DtxR, an iron-dependent transcriptional repressor that regulates the expression of siderophore gene clusters in Thermobifida fusca.

Thermobifida fusca is an aerobic, moderately thermophilic, filamentous soil bacterium. Iron is an essential metal involved in the vital metabolic functions in microorganisms. Thermobifida fusca was found to survive in the iron-deficiency condition and produce siderophores which synthesized to acquire iron. The iron transport was regulated by DtxR, a prototypic member of a superfamily of transition metal ion-activated transcriptional regulators. Tfu_0249 was found to be working as DtxR in T. fusca. The promoter regions of the three gene clusters related to the iron transport bound and regulated by Tfu_0249 were identified by bioinformatics analysis. The gel shift assays confirmed that Tfu_0249 bound the binding sites firmly on the upstream of three gene clusters. By comparing the binding sites of three clusters and gel shift assay, TWAGGTWAGSCTWACCTWA was found to be recognized and bound by Tfu_0249 to control iron transport in T. fusca.