title: Fep1 represses expression of the fission yeast Schizosaccharomyces pombe siderophore-iron transport system.
abstract: When iron repletes, Schizosaccharomyces pombe cells repress transcription of genes encoding components involved in the reductive iron transport system. Fep1 mediates this transcriptional control by interacting specifically with GATA-type cis-acting elements. To further investigate the role that Fep1 plays in iron homeostasis, we searched for additional Fep1-regulated genes. We found that str1+ is subject to negative transcriptional regulation, which is exerted through binding of Fep1 to a single GATA element in the str1+ promoter. Introduction of str1+ into a Saccharomyces cerevisiae fet3Delta arn1-4Delta strain led to assimilation of iron from ferrichrome, revealing that Str1 functions as a siderophore-iron transporter in S.pombe. We also identified two additional target genes of Fep1, named str2+ and str3+. We demonstrate that the str1+, str2+ and str3+ genes share a common promoter element, 5'-(A/T)GATAA-3'. We found that the N-terminal 241 residue segment of Fep1 expressed in Escherichia coli specifically interacts with the 5'-(A/T)GATAA-3' element present in each of these promoters. Consistent with this, constitutive high level str1+, str2+ and str3+ gene expression was observed in a fep1Delta mutant strain. Taken together, these results demonstrate that Fep1 occupies a central role in coordinating transcriptional regulation of genes encoding components of the reductive and non-reductive iron transport systems in fission yeast.
authors.affiliation: Département de Biochimie, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada.
authors.forename: Benoit
authors.initials: B
authors.lastname: Pelletier
authors.forename: Jude
authors.initials: J
authors.lastname: Beaudoin
authors.forename: Caroline C
authors.initials: CC
authors.lastname: Philpott
authors.forename: Simon
authors.initials: S
authors.lastname: Labbé
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D027682:Cation Transport Proteins / Q000096:biosynthesis / Q000235:genetics*; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D050980:GATA Transcription Factors; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000502:physiology*; D020218:Response Elements; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D016415:Sequence Alignment; D017262:Siderophores / Q000378:metabolism*; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C459859:Fep1 protein, S pombe; D050980:GATA Transcription Factors; D012097:Repressor Proteins; D029702:Schizosaccharomyces pombe Proteins; D017262:Siderophores; C476429:Str1 protein, S pombe; D014157:Transcription Factors; D007501:Iron