title: The RcnRA (YohLM) system of Escherichia coli: a connection between nickel, cobalt and iron homeostasis.
abstract: The transporter RcnA has previously been implicated in Ni(II) and Co(II) detoxification in E. coli probably through efflux. Here we demonstrate that the divergently described rcnA and rcnR gene products constitute a link between nickel, cobalt and iron homeostasis. Deletion of the rcnA gene resulted in increased cellular nickel, cobalt and iron concentrations. Expression of rcnA was induced by Ni(II) or Co(II). Overproduction of rcnR inhibited induction of rcnA by metal cations but RcnR did not bind to the rcnA promoter in vitro. When rcnR or fur, the gene of the global repressor of iron homeostasis, was deleted, expression of rcnA was also induced by iron. The promoter region of rcnA was positive in a Fur titration (FURTA) in vivo assay indicative of Fur binding. Thus, rcnA is part of the Fur regulon of E. coli. The implications of a connection between the homoeostasis of closely related transition metals are discussed.
authors.affiliation: Molecular Microbiology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06099, Halle/Saale, Germany.
authors.forename: Doreen
authors.initials: D
authors.lastname: Koch
authors.forename: Dietrich H
authors.initials: DH
authors.lastname: Nies
authors.forename: Gregor
authors.initials: G
authors.lastname: Grass
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology; D003035:Cobalt / Q000378:metabolism* / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology*; D007501:Iron / Q000378:metabolism* / Q000502:physiology; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D009532:Nickel / Q000378:metabolism* / Q000502:physiology; D018085:Regulon / Q000502:physiology; D012097:Repressor Proteins / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C501738:RcnA protein, E coli; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D003035:Cobalt; D009532:Nickel; D007501:Iron