title: Identification of an iron permease, cFTR1, in cyanobacteria involved in the iron reduction/re-oxidation uptake pathway.
abstract: Cyanobacteria are globally important primary producers and abundant in many iron-limited aquatic environments. The ways in which they take up iron are largely unknown, but reduction of Fe3+is an important step in the process. Here we report a special iron permease in Synechocystis, cFTR1, that is required for Fe3+uptake following Fe2+re-oxidation. The expression of cFTR1 is induced by iron starvation, and a mutant lacking the gene is abnormally sensitive to iron starvation. The cFTR1 protein localizes to the plasma membrane and contains the iron-binding motif "REXXE". Point-directed mutagenesis of the REXXE motif results in a sensitivity to Fe-deficiency. Measurements of iron (55Fe) uptake rate show that cFTR1 takes up Fe3+rather than Fe2+. The function of cFTR1 in Synechocystis could be genetically complemented by the iron permease, Ftr1p, of Saccharomyces cerevisiae, that is known to transport Fe3+produced by the oxidation of Fe2+via a multicopper oxidase. Unlike yeast Ftr1p, cyanobacterial cFTR1 probably obtains Fe3+primarily from the oxidation of Fe2+by oxygen. Growth assays show that the cFTR1 is required during oxygenic, photoautotrophic growth but not when oxygen production is inhibited during photoheterotrophic growth. In cyanobacteria, iron reduction/re-oxidation uptake pathway may represent their adaptation to oxygenated environments.
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Qiu
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Wen-Jing
authors.initials: WJ
authors.lastname: Lou
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Zheng-Ke
authors.initials: ZK
authors.lastname: Li
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Hai-Bo
authors.initials: HB
authors.lastname: Jiang
authors.affiliation: Department of Biology, McGill University, 1205 Docteur Penfield, Montreal, Québec, H3A 1B1, Canada.
authors.forename: Neil M
authors.initials: NM
authors.lastname: Price
authors.affiliation: School of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan, Hubei, 430079, People's Republic of China.
authors.forename: Bao-Sheng
authors.initials: BS
authors.lastname: Qiu
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D010084:Oxidation-Reduction; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D046939:Synechocystis / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D029701:Saccharomyces cerevisiae Proteins; D007501:Iron