Nur, a nickel‐responsive regulator of the Fur family, regulates superoxide dismutases and nickel transport in Streptomyces coelicolor

Abstract

SummaryNickel serves as a cofactor for various microbial enzymes including superoxide dismutase (SOD) found in Streptomyces spp. In Streptomyces coelicolor , nickel represses and induces production of Fecontaining and Ni-containing SODs, respectively, primarily at the transcriptional level. We identified the nickel-responsive regulator (Nur), a Fur (ferric-uptake regulator) homologue, which binds to the promoter region of the sodF gene encoding FeSOD in the presence of nickel. Disruption of the nur gene caused constitutive expression of FeSOD and no induction of NiSOD in the presence of nickel. The intracellular level of nickel was higher in a D nur mutant than in the wild type, suggesting that Nur also regulates nickel uptake in S. coelicolor . A putative nickel-transporter gene cluster ( nikABCDE ) was identified in the genome database. Its transcription was negatively regulated by Nur in the presence of nickel. Purified Nur protein bound to the nikA promoter region in a nickeldependent way. These results support the action of Nur as a regulator of nickel homeostasis and antioxidative response in S. coelicolor , and add a novel nickel-responsive member to the list of versatile metal-specific regulators of the Fur family.

Zinc-Responsive Regulation of Alternative Ribosomal Protein Genes inStreptomyces coelicolorInvolves Zur and σR

“…Zur is one of four members of the Fur family of metalloregulators in S. coelicolor. The other characterized members are FurS and CatR, which are thought to be redox-responsive regulators that control the expression of antioxidant genes, and Nur, which controls nickel uptake (1,19,33). The regulation of several C Ϫ R proteins by Zur in S. coelicolor concurs with results from studies of B. subtilis and M. tuberculosis (2,29).…”

The Zinc-Responsive Regulator Zur Controls a Zinc Uptake System and Some Ribosomal Proteins inStreptomyces coelicolorA3(2)

“…Other than iron, the list of specific metals that bind to Fur family regulators and hence specifically regulate their own homeostasis is increasing. Examples of the metalspecific Fur family regulators are Zur for zinc (39), Mur for manganese (13), and Nur for nickel (2). In E. coli, Zur is known to exhibit sensitivity to femtomolar levels of free intracellular zinc (36) and regulates the high-affinity zinc uptake system ZnuACB (40).…”

Expression of BfrH, a Putative Siderophore Receptor of Bordetella bronchiseptica , Is Regulated by Iron, Fur1, and the Extracellular Function Sigma Factor EcfI

“…PerR, the third Fur homologue in B. subtilis, represses the peroxide regulon (27). In S. coelicolor, FurA and CatR control expression of peroxidase and catalase A, respectively (1,27,63). Nur, which is implicated in nickel homeostasis, and Zur were recently described for S. coelicolor (1,63).…”

“…In S. coelicolor, FurA and CatR control expression of peroxidase and catalase A, respectively (1,27,63). Nur, which is implicated in nickel homeostasis, and Zur were recently described for S. coelicolor (1,63). To determine the roles of fur1 and fur2 in expression of ecfIR-bfrH in B. bronchiseptica, attempts were made to engineer deletion mutants of each of the genes.…”