title: Cytoplasmic localization of sterol transcription factors Upc2p and Ecm22p in S. cerevisiae.
abstract: Ergosterol homeostasis is a critical process for fungal cells. Paralogous zinc cluster transcription factors Upc2p and Ecm22p are major regulators of ergosterol biosynthesis in Saccharomyces cerevisiae. Upc2p and Ecm22p sense and respond to sterol depletion but their mechanism of activation has not been defined. Subcellular localization and functional expression of Upc2p-GFP and Ecm22p-GFP was monitored by fluorescence microscopy and flow cytometry in live yeast cells. Both fusion proteins localized to intracellular membranes and to perinuclear foci. Perinuclear localization of Upc2p-GFP and Ecm22p-GFP was increased when ergosterol biosynthesis was blocked by azole drug treatment. Nuclear localization in response to sterol depletion is consistent with the hypothesis that Upc2p and Ecm22p are trafficked from a membrane to the nucleus as a post-translational mechanism of sterol sensing.
authors.affiliation: Department of Global Health, School of Medicine and School of Public Health and Community Medicine, University of Washington, USA.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Marie
authors.forename: Sarah
authors.initials: S
authors.lastname: Leyde
authors.forename: Theodore C
authors.initials: TC
authors.lastname: White
mesh_terms: D001393:Azoles / Q000494:pharmacology; D003593:Cytoplasm / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D004875:Ergosterol / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001393:Azoles; C465208:ECM22 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C113958:UPC2 protein, S cerevisiae; D049452:Green Fluorescent Proteins; D004875:Ergosterol