title: Functional expression of mouse mdr1 in Escherichia coli.
abstract: We describe functional expression of the mouse multidrug-resistance protein (P-glycoprotein; P-gp) in an Escherichia coli mutant defective in the outer membrane protease ompT. Heterologously expressed mdr1 appears as an unglycosylated species with an apparent molecular mass of 140 kDa in the membrane of the mutant. Unglycosylated mdr1 retains the ability to bind the photoactivatable drug analog [125I]iodoarylazidoprazosin and confers resistance to tetraphenylphosphonium (TPP+) and tetraphenylarsonium (TPA+), known mdr1 substrates. In vivo resistance is linked to reduced cellular accumulation and energy-dependent efflux of the lipophilic cations. Surprisingly, discrete mutations in the predicted nucleotide binding folds of mdr1 that abolish drug resistance in mammalian cells have no apparent effect on TPA+ efflux via mdr1 in E. coli.
authors.affiliation: Howard Hughes Medical Institute, Department of Physiology, University of California, Los Angeles 90024-1662.
authors.forename: E
authors.initials: E
authors.lastname: Bibi
authors.forename: P
authors.initials: P
authors.lastname: Gros
authors.forename: H R
authors.initials: HR
authors.lastname: Kaback
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000668:Ampicillin Resistance / Q000235:genetics; D000818:Animals; D001152:Arsenicals / Q000378:metabolism / Q000494:pharmacology; D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004351:Drug Resistance / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000378:metabolism; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009861:Onium Compounds / Q000378:metabolism / Q000494:pharmacology; D009943:Organophosphorus Compounds / Q000378:metabolism / Q000494:pharmacology; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D001152:Arsenicals; D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D009861:Onium Compounds; D009943:Organophosphorus Compounds; D011994:Recombinant Proteins; C009439:tetraphenylarsonium; D007544:Isopropyl Thiogalactoside; C013289:tetraphenylphosphonium