title: Ferric iron reduction and iron assimilation in Saccharomyces cerevisiae.
abstract: We have used the yeast Saccharomyces cerevisiae as a model organism to study the role of ferric iron reduction in eucaryotic iron uptake. S. cerevisiae is able to utilize ferric chelates as an iron source by reducing the ferric iron to the ferrous form, which is subsequently internalized by the cells. A gene (FRE1) was identified which encodes a protein required for both ferric iron reduction and efficient ferric iron assimilation, thus linking these two activities. The predicted FRE1 protein appears to be a membrane protein and shows homology to the beta-subunit of the human respiratory burst oxidase. These data suggest that FRE1 is a structural component of the ferric reductase. Subcellular fractionation studies showed that the ferric reductase activity of isolated plasma membranes did not reflect the activity of the intact cells, implying that cellular integrity was necessary for function of the major S. cerevisiae ferric reductase. An NADPH-dependent plasma membrane ferric reductase was partially purified from plasma membranes. Preliminary evidence suggests that the cell surface ferric reductase may, in addition to mediating cellular iron uptake, help modulate the intracellular redox potential of the yeast cell.
authors.affiliation: Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
authors.forename: G J
authors.initials: GJ
authors.lastname: Anderson
authors.forename: E
authors.initials: E
authors.lastname: Lesuisse
authors.forename: A
authors.initials: A
authors.lastname: Dancis
authors.forename: D G
authors.initials: DG
authors.lastname: Roman
authors.forename: P
authors.initials: P
authors.lastname: Labbe
authors.forename: R D
authors.initials: RD
authors.lastname: Klausner
mesh_terms: D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D038181:FMN Reductase; D005290:Ferric Compounds / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005800:Genes, Fungal; D006801:Humans; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics; D009249:NADP / Q000494:pharmacology; D010084:Oxidation-Reduction; D016897:Respiratory Burst; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000378:metabolism*; D017385:Sequence Homology
chemical_list: D005290:Ferric Compounds; D009249:NADP; D007501:Iron; D038181:FMN Reductase; D009247:NADH, NADPH Oxidoreductases; C023903:ferric citrate iron reductase