title: Iron homeostasis in the fission yeast Schizosaccharomyces pombe.
abstract: Schizosaccharomyces pombe has acquisition processes for iron, an essential nutrient. One pathway consists to produce, excrete, and capture siderophore-iron complexes. A second pathway requires enzymatic reduction of ferric iron at the cell surface prior to uptake by a permease-oxidase complex. Genes encoding proteins involved in iron assimilation are transcriptionally regulated as a function of iron availability. Under high iron conditions, the GATA-type regulator Fep1 represses the expression of iron uptake genes. The repressor function of Fep1 requires the presence of the Tup11 or Tup12 transcriptional co-repressor. Under low iron conditions, two regulatory mechanisms occur. First, the iron transport genes are highly induced. Second, there is a transcription factor cascade implicating the heteromeric CCAAT-binding complex that turns off a set of genes encoding iron-utilizing proteins, presumably to avoid a futile expenditure of energy in producing iron-using proteins that lack the necessary cofactor to function. Thus, collectively, these regulatory responses to variations in iron concentrations ensure that iron is present within cells for essential biochemical reactions, yet prevent the accumulation of iron or iron-using proteins to deleterious levels.
authors.affiliation: Département de Biochimie, Faculté de médecine, Université de Sherbrooke, 3001 12e Ave Nord, Sherbrooke, QC, Canada J1H 5N4. Simon.Labbe@USherbrooke.ca
authors.forename: Simon
authors.initials: S
authors.lastname: Labbé
authors.forename: Benoit
authors.initials: B
authors.lastname: Pelletier
authors.forename: Alexandre
authors.initials: A
authors.lastname: Mercier
mesh_terms: D001692:Biological Transport / Q000502:physiology; D050980:GATA Transcription Factors / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D010084:Oxidation-Reduction; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C459859:Fep1 protein, S pombe; D050980:GATA Transcription Factors; D029702:Schizosaccharomyces pombe Proteins; D007501:Iron