title: Protonation of a glutamate residue modulates the dynamics of the drug transporter EmrE.
abstract: Secondary active transport proteins play a central role in conferring bacterial multidrug resistance. In this work, we investigated the proton-coupled transport mechanism for the Escherichia coli drug efflux pump EmrE using NMR spectroscopy. Our results show that the global conformational motions necessary for transport are modulated in an allosteric fashion by the protonation state of a membrane-embedded glutamate residue. These observations directly correlate with the resistance phenotype for wild-type EmrE and the E14D mutant as a function of pH. Furthermore, our results support a model in which the pH gradient across the inner membrane of E. coli may be used on a mechanistic level to shift the equilibrium of the transporter in favor of an inward-open resting conformation poised for drug binding.
authors.affiliation: Department of Chemistry, New York University, New York, New York, USA.
authors.forename: Anindita
authors.initials: A
authors.lastname: Gayen
authors.affiliation: Department of Chemistry, New York University, New York, New York, USA.
authors.forename: Maureen
authors.initials: M
authors.lastname: Leninger
authors.affiliation: Department of Chemistry, New York University, New York, New York, USA.
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Traaseth
mesh_terms: D017920:Antiporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004996:Ethidium / Q000494:pharmacology; D005971:Glutamates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011487:Protein Conformation; D011522:Protons
chemical_list: D017920:Antiporters; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; D005971:Glutamates; D008081:Liposomes; D011522:Protons; C075436:EmrE protein, E coli; D004996:Ethidium