Regulation of the furA and catC operon, encoding a ferric uptake regulatorhomologue and catalase-peroxidase, respectively, in Streptomyces coelicolor A3(2)

We isolated the catC gene, encoding catalase-peroxidase in Streptomyces coe licolor, using sequence homology with the katG gene from Escherichia coli. Upstream of the catC gene, an open reading frame (furA) encoding a homologu e of ferric uptake regulator (Fur) was identified. S1 mapping analysis indi cated that the furA gene was cotranscribed with the catC gene. The transcri ptional start site of the furA-catC mRNA was mapped to the translation star t codon ATG of the furA gene. The putative promoter contains consensus -10 and -35 elements similar to those recognized by sigma(HrdB), th, major sigm a factor of S. coelicolor. The transcripts were produced maximally at late- exponential phase and decreased at the stationary phase in liquid culture. The change in the amount of mRNA was consistent with that of CatC protein a nd enzyme activity. When the furA gene was introduced into S. lividans on a multicopy plasmid, the increased production of catC transcripts and protei n product at late growth phase was inhibited, implying a role for FurA as t he negative regulator of the furA-catC operon. FurA protein hound to its ow n promoter region between -59 and -39 nucleotides from the transcription st art site. The binding affinity of FurA increased under reducing conditions and in the presence of metals such as Ni2+, Mn2+, Zn2+, or Fe2+. Addition o f these metals to the growth medium decreased the production of CatC protei n, consistent with the role of FurA as a metal-dependent repressor.