The ATP-binding cassette multidrug transporter Snq2 of Saccharomyces cerevisiae: a novel target for the transcription factors Pdr1 and Pdr3

Mol Microbiol. 1996 Apr;20(1):109-17. doi: 10.1111/j.1365-2958.1996.tb02493.x.


Pleiotropic drug resistance (PDR) in the yeast Saccharomyces cerevisiae can arise from overexpression of ATP-binding cassette (ABC) efflux pumps such as Pdr5 and Snq2. Mutations in the transcription factor genes PDR1 and PDR3 are also associated with PDR. We show here that a pdr1-3 mutant exhibits a PDR phenotype, including elevated resistance to the mutagen 4-nitroquinoline-N-oxide, a known substrate for Snq2 but not for Pdr5. Northern analysis and immunoblotting demonstrated that the SNQ2 gene is 10-fold overexpressed in a pdr1-3 gain-of-function mutant strain, whereas Snq2 expression is severely reduced in a delta pdr1 deletion strain, and almost abolished in a delta pdr1 delta pdr3 double disruptant when compared to the PDR1 strain. However, expression of the Ste6 a-factor pheromone transporter, another yeast ABC transporter not associated with PDR, is unaffected in pdr1-3 mutant cells and in strains carrying delta pdr1, delta pdr3, or delta pdr1 delta pdr3 deletions. Finally, DNA footprint analysis revealed that the SNQ2 promoter contains three binding sites for Pdr3. Our results identify SNQ2 as a novel target for both Pdr1 and Pdr3, and demonstrate that the PDR phenotype of a pdr1-3 mutant strain results from overexpression of more than one ABC drug-efflux pump.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 4-Nitroquinoline-1-oxide / pharmacology
  • ATP-Binding Cassette Transporters / genetics*
  • ATP-Binding Cassette Transporters / metabolism
  • Antifungal Agents / pharmacology
  • Binding Sites
  • Cycloheximide / pharmacology
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Drug Resistance, Microbial / genetics*
  • Drug Resistance, Multiple / genetics
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • Glycoproteins*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mutagens / pharmacology
  • Mutation
  • Promoter Regions, Genetic
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / drug effects
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • ATP-Binding Cassette Transporters
  • Antifungal Agents
  • DNA-Binding Proteins
  • Fungal Proteins
  • Glycoproteins
  • Membrane Proteins
  • Mutagens
  • PDR1 protein, S cerevisiae
  • PDR3 protein, S cerevisiae
  • PDR5 protein, S cerevisiae
  • Recombinant Fusion Proteins
  • SNQ2 protein, S cerevisiae
  • STE6 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Trans-Activators
  • Transcription Factors
  • 4-Nitroquinoline-1-oxide
  • Cycloheximide