Hyperactive forms of the Pdr1p transcription factor fail to respond to positive regulation by the hsp70 protein Pdr13p.
Multidrug resistance in Saccharomyces cerevisiae is commonly associated with the overproduction of ATP-binding cassette transporter proteins such as Pdr5p or Yor1p. The Cys6-Zn(II)2 cluster-containing transcription factors Pdr1p and Pdr3p are key regulators of expression of these pleiotropic drug resistance (PDR) loci. Previous experiments have demonstrated that the Hsp70 protein encoded by the PDR13 gene is a positive regulator of Pdr1p function. We have examined the mechanism underlying the control of Pdr1p by Pdr13p. Expression of deletion, insertion and amino acid substitution mutant variants of Pdr1p suggest that the centre region of the transcription factor is the target for Pdr13p-mediated positive regulation. Immunological and fusion protein analyses demonstrate that Pdr13p is located in the cytoplasm, while Pdr1p is found in the nucleus. Biochemical fractionation experiments indicate that Pdr13p is associated with a high-molecular-weight complex and suggest the association of some fraction of Pdr13p with ribosomes.
Hallstrom
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Molecular Biology Program and the Department of Physiology and Biophysics, 5-430 Bowen Science Building, University of Iowa, Iowa City, IA 52242, USA.
Moye-Rowley
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D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D002499:Centrifugation, Density Gradient; D003513:Cycloheximide / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial / Q000235:genetics; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D049452:Green Fluorescent Proteins; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D017354:Point Mutation; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors
D000935:Antifungal Agents; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D008164:Luminescent Proteins; C085480:PDR1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D003513:Cycloheximide