title: Mutations of charged amino acids at the cytoplasmic end of transmembrane helix 2 affect transport activity of the budding yeast multidrug resistance protein Pdr5p.
abstract: Pdr5p is a major ATP-binding cassette (ABC) transporter in Saccharomyces cerevisiae. It displays a sequence and functional homology to the pathogenic Candida albicans multidrug resistance protein Cdr1p. The transmembrane helices of Pdr5p act in substrate recognition, binding, translocation and eventual removal of toxic substances out of the plasma membrane via the formation of a binding pocket. In this study, we identify two novel Pdr5 mutants (E574K and E580K), which exhibit impaired substrate efflux functions. Both mutants remained hypersensitive to all tested Pdr5p substrates without affecting their protein expression levels, localization or ATPase activities. As E574 and E580 are both located adjacent to the predicted cytoplasmic end of transmembrane helix 2, this implies that such charged residues are functionally essential for Pdr5p. Molecular docking studies suggest the possibility that oppositely charged substitution at residue E574 may disturb the interaction between the substrates and Pdr5p, resulting in impaired transport activity. Our results present new evidence, suggesting that transmembrane helix 2 plays an important role for the efflux function of Pdr5p.
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Weiwang
authors.initials: W
authors.lastname: Dou
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhu
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Tanjun
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China College of Life Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Han
authors.initials: H
authors.lastname: Li
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolism Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China Zhejiang Provincial Key Laboratory for Microbial Biochemistry and Metabolism Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China guanwj@zju.edu.cn.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Guan
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D000935:Antifungal Agents / Q000378:metabolism* / Q000494:pharmacology; D062105:Molecular Docking Simulation; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D018528:ATP-Binding Cassette Transporters; D000935:Antifungal Agents; D050505:Mutant Proteins; C092438:PDR5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins
keywords: ABC transporter; Pdr5p; charged amino acid; drug resistance; transmembrane helix; yeast