title: A mutation in intracellular loop 4 affects the drug-efflux activity of the yeast multidrug resistance ABC transporter Pdr5p.
abstract: Multidrug resistance protein Pdr5p is a yeast ATP-binding cassette (ABC) transporter in the plasma membrane. It confers multidrug resistance by active efflux of intracellular drugs. However, the highly polymorphic Pdr5p from clinical strain YJM789 loses its ability to expel azole and cyclohexmide. To investigate the role of amino acid changes in this functional change, PDR5 chimeras were constructed by segmental replacement of homologous BY4741 PDR5 fragments. Functions of PDR5 chimeras were evaluated by fluconazole and cycloheximide resistance assays. Their expression, ATPase activity, and efflux efficiency for other substrates were also analyzed. Using multiple lines of evidence, we show that an alanine-to-methionine mutation at position 1352 located in the predicted short intracellular loop 4 significantly contributes to the observed transport deficiency. The degree of impairment is likely correlated to the size of the mutant residue.
authors.affiliation: College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China.
authors.forename: Xiaoxian
authors.initials: X
authors.lastname: Guo
authors.forename: Jingkai
authors.initials: J
authors.lastname: Li
authors.forename: Tanjun
authors.initials: T
authors.lastname: Wang
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Yudong
authors.initials: Y
authors.lastname: Li
authors.forename: Zhenglong
authors.initials: Z
authors.lastname: Gu
authors.forename: Xuming
authors.initials: X
authors.lastname: Mao
authors.forename: Wenjun
authors.initials: W
authors.lastname: Guan
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Li
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D000935:Antifungal Agents / Q000493:pharmacokinetics*; D003513:Cycloheximide / Q000494:pharmacology; D004252:DNA Mutational Analysis; D018432:Drug Resistance, Multiple / Q000235:genetics*; D015725:Fluconazole / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000502:physiology; D030781:Organisms, Genetically Modified; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D015003:Yeasts / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; C092438:PDR5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015725:Fluconazole; D003513:Cycloheximide