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Titolo:
A model for coupling of H+ and substrate fluxes based on "time-sharing" ofa common binding site
Autore:
Yerushalmi, H; Schuldiner, S;
Indirizzi:
Hebrew Univ Jerusalem, Alexander Silberman Inst Life Sci, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 -91904 Jerusalem, Israel
Titolo Testata:
BIOCHEMISTRY
fascicolo: 48, volume: 39, anno: 2000,
pagine: 14711 - 14719
SICI:
0006-2960(200012)39:48<14711:AMFCOH>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
METAL-TETRACYCLINE/H+ ANTIPORTER; VESICULAR MONOAMINE TRANSPORTER; PUTATIVE TRANSMEMBRANE HELICES; MULTIDRUG-RESISTANCE PROTEIN; MEMBRANE-SPANNING SEGMENTS; ESCHERICHIA-COLI; LACTOSE PERMEASE; MELIBIOSE PERMEASE; CHARGED RESIDUES; NEUROTRANSMITTER TRANSPORTERS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
69
Recensione:
Indirizzi per estratti:
Indirizzo: Schuldiner, S Hebrew Univ Jerusalem, Alexander Silberman Inst Life Sci, IL-91904 Jerusalem, Israel Hebrew Univ Jerusalem Jerusalem Israel IL-91904 em, Israel
Citazione:
H. Yerushalmi e S. Schuldiner, "A model for coupling of H+ and substrate fluxes based on "time-sharing" ofa common binding site", BIOCHEM, 39(48), 2000, pp. 14711-14719

Abstract

Both prokaryotic and eukaryotic cells contain an array of membrane transport systems maintaining the cellular homeostasis. Some of them (primary pumps) derive energy from redox reactions, ATP hydrolysis, or light absorption,whereas others (ion-coupled transporters) utilize ion electrochemical gradients for active transport. Remarkable progress has been made in understanding the molecular mechanism of coupling in some of these systems. In many cases carboxylic residues are essential for either binding or coupling. Herewe suggest a model for the molecular mechanism of coupling in EmrE, an Escherichia coli 12-kDa multidrug transporter, EmrE confers resistance to a variety of toxic cations by removing them from the cell interior in exchange for two protons. EmrE has only one membrane-embedded charged residue, Glu-14, which is conserved in more than 50 homologous proteins. We have used mutagenesis and chemical modification to show that Glu-14 is part of the substrate-binding site. Its role in proton binding and translocation was shown by a study of the effect of pH on ligand binding, uptake, efflux, and exchange reactions. The studies suggest that Glu-14 is an essential part of a binding site, which is common to substrates and protons. The occupancy of thissite by H+ and substrate is mutually exclusive and provides the basis of the simplest coupling for two fluxes.

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Documento generato il 10/04/20 alle ore 02:39:45