Complex interplay among regulators of drug resistance genes in Saccharomyces cerevisiae.
The Gal4p family of yeast zinc cluster proteins comprises regulators of multidrug resistance genes. For example, Pdr1p and Pdr3p bind as homo- or heterodimers to pleiotropic drug response elements (PDREs) found in promoters of target genes. Other zinc cluster activators of multidrug resistance genes include Stb5p and Yrr1p. To better understand the interplay among these activators, we have performed native co-immunoprecipitation experiments using strains expressing tagged zinc cluster proteins from their natural chromosomal locations. Interestingly, Stb5p is found predominantly as a Pdr1p heterodimer and shows little homodimerization. No interactions of Stb5p with Pdr3p or Yrr1p could be detected in our assays. In contrast to Stb5p, Yrr1p is only detected as a homodimer. Similar results were obtained using glutathione S-transferase pull-down assays. Importantly, the purified DNA binding domains of Stb5p and Pdr1p bound to a PDRE as heterodimers in vitro. These results suggest that the DNA binding domains of Pdr1p and Stb5p are sufficient for heterodimerization. Our data demonstrate a complex interplay among these activators and suggest that Pdr1p is a master drug regulator involved in recruiting other zinc cluster proteins to fine tune the regulation of multidrug resistance genes.
Akache
Bassel
B
Department of Medicine, Royal Victoria Hospital, McGill University, Montréal, Québec H3A 1A1, Canada.
MacPherson
Sarah
S
Sylvain
Marc-André
MA
Turcotte
Bernard
B
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D015153:Blotting, Western; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D025141:Drug Resistance, Fungal; D018432:Drug Resistance, Multiple; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D008954:Models, Biological; D005810:Multigene Family; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*; D015032:Zinc / Q000737:chemistry
D018528:ATP-Binding Cassette Transporters; C466995:PDR11 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C488251:Stb5 protein, S cerevisiae; D014157:Transcription Factors; C481277:Yrr1 protein, S cerevisiae; D004247:DNA; D005982:Glutathione Transferase; D015032:Zinc