title: The yeast zinc finger regulators Pdr1p and Pdr3p control pleiotropic drug resistance (PDR) as homo- and heterodimers in vivo.
abstract: The transcription factors Pdr1p and Pdr3p from Saccharomyces cerevisiae mediate pleiotropic drug resistance (PDR) by controlling expression of ATP-binding cassette (ABC) transporters such as Pdr5p, Snq2p and Yor1p. Previous in vitro studies demonstrated that Pdr1p and Pdr3p recognize so-called pleiotropic drug resistance elements (PDREs) in the promoters of target genes. In this study, we show that both Pdr1p and Pdr3p are phosphoproteins; Pdr3p isoforms migrate as two bands in gel electrophoresis, reflecting two distinct phosphorylation states. Most importantly, native co-immunoprecipitation experiments, using functional epitope-tagged Pdr1p/Pdr3p variants, demonstrate that Pdr1p and Pdr3p can form both homo- and heterodimers in vivo. Furthermore, in vivo footprinting of PDRE-containing promoters demonstrate that Pdr1p/Pdr3p constitutively occupy both perfect and degenerate PDREs in vivo. Thus, in addition to interaction with other regulators, differential dimerization provides a plausible explanation for the observation that Pdr3p and Pdr1p can both positively and negatively control PDR promoters with different combinations of perfect and degenerate PDREs.
authors.affiliation: Institute of Medical Biochemistry, Department of Molecular Genetics, University of Vienna, Vienna BioCenter, A-1030 Vienna, Austria.
authors.forename: Yasmine M
authors.initials: YM
authors.lastname: Mamnun
authors.forename: Rudy
authors.initials: R
authors.lastname: Pandjaitan
authors.forename: Yannick
authors.initials: Y
authors.lastname: Mahé
authors.forename: Agnés
authors.initials: A
authors.lastname: Delahodde
authors.forename: Karl
authors.initials: K
authors.lastname: Kuchler
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D019281:Dimerization; D026141:Drug Resistance, Multiple, Fungal / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D011401:Promoter Regions, Genetic / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D016335:Zinc Fingers
chemical_list: D018528:ATP-Binding Cassette Transporters; D004268:DNA-Binding Proteins; C085480:PDR1 protein, S cerevisiae; C089261:PDR3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors