title: The late-annotated small ORF LSO1 is a target gene of the iron regulon of Saccharomyces cerevisiae.
abstract: We have identified a new downstream target gene of the Aft1/2-regulated iron regulon in budding yeast Saccharomyces cerevisiae, the late-annotated small open reading frame LSO1. LSO1 transcript is among the most highly induced from a transcriptome analysis of a fet3-1 mutant grown in the presence of the iron chelator bathophenanthrolinedisulfonic acid. LSO1 has a paralog, LSO2, which is constitutively expressed and not affected by iron availability. In contrast, we find that the LSO1 promoter region contains three consensus binding sites for the Aft1/2 transcription factors and that an LSO1-lacZ reporter is highly induced under low-iron conditions in a Aft1-dependent manner. The expression patterns of the Lso1 and Lso2 proteins mirror those of their mRNAs. Both proteins are localized to the nucleus and cytoplasm, but become more cytoplasmic upon iron deprivation consistent with a role in iron transport. LSO1 and LSO2 appear to play overlapping roles in the cellular response to iron starvation since single lso1 and lso2 mutants are sensitive to iron deprivation and this sensitivity is exacerbated when both genes are deleted.
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado, 80045.
authors.forename: Xiuxiang
authors.initials: X
authors.lastname: An
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado, 80045.
authors.forename: Caiguo
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado, 80045.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Sclafani
authors.affiliation: Division of Hematology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, 80045.
authors.forename: Paul
authors.initials: P
authors.lastname: Seligman
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, Colorado, 80045.
authors.forename: Mingxia
authors.initials: M
authors.lastname: Huang
mesh_terms: D001665:Binding Sites; D015966:Gene Expression Regulation, Fungal; D007501:Iron / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D018085:Regulon; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D007501:Iron
keywords: Cell cycle; iron; regulon; transcriptome; yeast