Nur, a nickel-responsive regulator of the Fur family, regulates superoxide dismutases and nickel transport in Streptomyces coelicolor.
Nickel 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 Fe-containing 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 Deltanur 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 nickel-dependent 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.
School of Biological Sciences and Institute of Microbiology, Seoul National University, Korea.
Bo-Eun
BE
Ahn
Joonseok
J
Cha
Eun-Jin
EJ
Lee
Ah-Reum
AR
Han
Charles J
CJ
Thompson
Jung-Hye
JH
Roe
D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D001692:Biological Transport / Q000235:genetics; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D009532:Nickel / Q000378:metabolism*; D009876:Operon / Q000235:genetics; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics*
D018528:ATP-Binding Cassette Transporters; D012097:Repressor Proteins; D009532:Nickel; D013482:Superoxide Dismutase