Mahé Y, Parle-McDermott A, Nourani A, Delahodde A, Lamprecht A, Kuchler K
Department of Molecular Genetics, University and Biocenter of Vienna, Vienna, Austria.
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.
酿酒酵母中的多药耐药性（PDR）可能源于ATP结合盒（ABC）外排泵（如Pdr5和Snq2）的过表达。转录因子基因PDR1和PDR3的突变也与PDR相关。我们在此表明，pdr1 - 3突变体表现出PDR表型，包括对诱变剂4 - 硝基喹啉 - N - 氧化物的抗性增强，4 - 硝基喹啉 - N - 氧化物是Snq2的已知底物而非Pdr5的底物。Northern分析和免疫印迹表明，SNQ2基因在pdr1 - 3功能获得性突变株中过表达10倍，而在Δpdr1缺失株中Snq2表达严重降低，与PDR1菌株相比，在Δpdr1Δpdr3双缺失株中几乎完全消失。然而，另一种与PDR无关的酵母ABC转运蛋白Ste6 a因子信息素转运蛋白的表达在pdr1 - 3突变细胞以及携带Δpdr1、Δpdr3或Δpdr1Δpdr3缺失的菌株中未受影响。最后，DNA足迹分析表明SNQ2启动子包含三个Pdr3结合位点。我们的结果确定SNQ2是Pdr1和Pdr3的一个新靶点，并证明pdr1 - 3突变株的PDR表型是由一种以上ABC药物外排泵的过表达导致的。
