title: Control of 26S proteasome expression by transcription factors regulating multidrug resistance in Saccharomyces cerevisiae.
abstract: In eukaryotic cells, intracellular proteolysis occurs mainly via the ubiquitin-proteasome system. Expression of the yeast proteasome is under the control of the transcription factor, Rpn4p (also known as Son1p/Ufd5p). We show here that the RPN4 gene promoter contains regulatory sequences that bind Pdr1p and Pdr3p, two homologous zinc finger-containing transcription factors, which mediate multiple drug resistance through the expression of membrane transporter proteins. Mutations in the RPN4 Pdr1p/Pdr3p binding sites lead to decreased expression of the proteasome RPT6 gene and to defective ubiquitin-mediated proteolysis. Pdr3p, but not Pdr1p, is required for normal levels of intracellular proteolysis, indicating that the two transcription factors have distinct functions in the control of RPN4 expression. The RPN4 promoter contains an additional sequence that binds Yap1p, a bZIP-type transcription factor that plays an important role in the oxidative stress response and multidrug resistance. We also show that the Yap1p response element is important in the transactivation of RPN4 by Yap1p. In yeast cells lacking Pdr1p, ubiquitin-Pro-beta-galactosidase, a short-lived protein used to assay proteasome activity, is stabilized by the loss of Yap1p. These data demonstrate that the ubiquitin-proteasome system is controlled by transcriptional regulators of multidrug resistance via RPN4 expression.
authors.affiliation: Unité de Biochimie Physiologique, Université Catholique de Louvain, Croix du Sud 2-20, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Owsianik
authors.forename: Lisabetta
authors.initials: L
authors.lastname: Balzi l
authors.forename: Michel
authors.initials: M
authors.lastname: Ghislain
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D026141:Drug Resistance, Multiple, Fungal; D015966:Gene Expression Regulation, Fungal; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D000935:Antifungal Agents; D004268:DNA-Binding Proteins; C085480:PDR1 protein, S cerevisiae; C089261:PDR3 protein, S cerevisiae; C119430:RPN4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C086677:YAP1 protein, S cerevisiae; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease