Multiple flavonoid-binding sites within multidrug resistance protein MRP1.
Recombinant nucleotide-binding domains (NBDs) from human multidrug resistance protein MRP1 were overexpressed in bacteria and purified to measure their direct interaction with high-affinity flavonoids, and to evaluate a potential correlation with inhibition of MRP1-mediated transport activity and reversion of cellular multidrug resistance. Among different classes of flavonoids, dehydrosilybin exhibited the highest affinity for both NBDs, the binding to N-terminal NBD1 being prevented by ATP. Dehydrosilybin increased vanadate-induced 8-N3-[alpha-32P]ADP trapping, indicating stimulation of ATPase activity. In contrast, dehydrosilybin strongly inhibited leukotriene C4 (LTC4) transport by membrane vesicles from MRP1-transfected cells, independently of reduced glutathione, and chemosensitized cell growth to vincristine. Hydrophobic C-isoprenylation of dehydrosilybin increased the binding affinity for NBD1, but outsite the ATP site, lowered the increase in vanadate-induced 8-N3-[alpha-32P]ADP trapping, weakened inhibition of LTC4 transport which became glutathione dependent, and induced some cross-resistance. The overall results indicate multiple binding sites for dehydrosilybin and its derivatives, on both cytosolic and transmembrane domains of MRP1.
Trompier
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D
Institut de Biologie et Chimie des Protéines, UMR5086 CNRS/Université Claude Bernard-Lyon I, IFR128 BioSciences Lyon-Gerland, 7 Passage du Vercors, 69367 Lyon, France.
Baubichon-Cortay
H
H
Chang
X-B
XB
Maitrejean
M
M
Barron
D
D
Riordon
J R
JR
Di Pietro
A
A
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D001665:Binding Sites; D003001:Cloning, Molecular; D006224:Cricetinae; D005419:Flavonoids / Q000378:metabolism*; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D014750:Vincristine / Q000494:pharmacology
D000244:Adenosine Diphosphate; D000972:Antineoplastic Agents, Phytogenic; D005419:Flavonoids; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D014750:Vincristine