title: ERG6 and PDR5 regulate small lipophilic drug accumulation in yeast cells via distinct mechanisms.
abstract: Diagnosis and circumvention of multi-drug resistance requires an understanding of the underlying cellular mechanisms. In the model organism Saccharomyces cerevisiae, deletions of PDR5 or ERG6 increase sensitivity to many small lipophilic drugs. Pdr5p is a plasma membrane ATP-binding cassette transporter that actively exports drugs, thereby lowering their intracellular levels. The mechanism by which ERG6, an enzyme in sterol biosynthesis, affects drug accumulation is less clear. We show here that ERG6 limits the rate of passive drug diffusion across the membrane, without affecting Pdr5p-mediated drug export. Consistent with their action by distinct mechanisms, PDR5 and ERG6 effects on drug accumulation are additive.
authors.affiliation: Division of Biochemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Emter
authors.forename: Antje
authors.initials: A
authors.lastname: Heese-Peck
authors.forename: Anastasia
authors.initials: A
authors.lastname: Kralli
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D003513:Cycloheximide / Q000378:metabolism / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008780:Methyltransferases / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D012235:Rhodamines / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D018528:ATP-Binding Cassette Transporters; D005456:Fluorescent Dyes; D005656:Fungal Proteins; D008565:Membrane Proteins; C092438:PDR5 protein, S cerevisiae; D012235:Rhodamines; D029701:Saccharomyces cerevisiae Proteins; C026188:rhodamine 6G; D003513:Cycloheximide; D008780:Methyltransferases; C022670:delta 24-sterol methyltransferase