title: Prenyl-flavonoids as potent inhibitors of the Pdr5p multidrug ABC transporter from Saccharomyces cerevisiae.
abstract: The Pdr5p multidrug ABC ("ATP-binding cassette) transporter was highly overexpressed in plasma membranes from a yeast strain exhibiting both pdr1-3 gain-of-function mutation in the transcription factor-encoding gene PDR1 and disruption of genes encoding other plasma membrane ABC transporters. Solubilized and purified Pdr5p displayed a tryptophan-characteristic intrinsic fluorescence, whose quenching was used to monitor interactions with substrates and effectors. The transporter exhibited a magnesium-dependent binding affinity for ATP and its fluorescent analogue 2'(3')-N-methylanthraniloyl-ATP, producing a marked fluorescence resonance-energy transfer. It also bound a series of known drug substrates and modulators. Interestingly, yeast Pdr5p interacted with flavonoids recently found to bind to cancer cell P-glycoprotein and to the protozoan parasite multidrug transporter. The extent of high-affinity binding of prenyl-flavonoids to purified Pdr5p was correlated to their efficiency to inhibit energy-dependent quenching of rhodamine 6G fluorescence catalyzed by Pdr5p-enriched plasma membranes. The hydrophobic flavonoid derivative 6-(3, 3-dimethylallyl)galangin was the most efficient, with a K(i) of 0.18 microM for competitive inhibition of the MgATP-dependent quenching of rhodamine 6G fluorescence. In contrast, inhibition of either ATP or UTP hydrolysis occurred at much higher concentrations and appeared to be noncompetitive. Prenyl-flavonoids therefore behave as potent inhibitors of drug binding to the yeast Pdr5p ABC transporter.
authors.affiliation: Laboratoire de Biochimie Structurale et Fonctionnelle, Institut de Biologie et Chimie des Prot¿eines, UPR 412 du Centre National de la Recherche Scientifique, Lyon, France.
authors.forename: G
authors.initials: G
authors.lastname: Conseil
authors.forename: A
authors.initials: A
authors.lastname: Decottignies
authors.forename: J M
authors.initials: JM
authors.lastname: Jault
authors.forename: G
authors.initials: G
authors.lastname: Comte
authors.forename: D
authors.initials: D
authors.lastname: Barron
authors.forename: A
authors.initials: A
authors.lastname: Goffeau
authors.forename: A
authors.initials: A
authors.lastname: Di Pietro
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005419:Flavonoids / Q000494:pharmacology*; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015394:Molecular Structure; D011485:Protein Binding / Q000187:drug effects; D011755:Pyrophosphatases / Q000378:metabolism; D012235:Rhodamines; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors; D014364:Tryptophan / Q000737:chemistry
chemical_list: D018528:ATP-Binding Cassette Transporters; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D005656:Fungal Proteins; D008565:Membrane Proteins; C085480:PDR1 protein, S cerevisiae; C092438:PDR5 protein, S cerevisiae; D012235:Rhodamines; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C026188:rhodamine 6G; D014364:Tryptophan; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D011755:Pyrophosphatases; C023278:uridine triphosphatase; D008274:Magnesium