Negative regulation of the gene for Fe-containing superoxide dismutase by an Ni-responsive factor in Streptomyces coelicolor

In Streptomyces coelicolor, transcription of the sodF genes, encoding Fe-co ntaining superoxide dismutases, is negatively regulated by nickel. Gel mobi lity shift assays,vith sodF1 promoter fragments and cell extracts from the A3(2) strain indicate the presence of a nickel-responsive DNA-binding prote in, most likely a transcriptional repressor. The boundary for the Ni-respon sive cis-acting region was identified both in vitro and vivo. Ni does not r egulate the level of the putative repressor but only the binding competence of this protein.