HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 280, Issue 44, 36857-36864, November 4, 2005

This Article Full Text Full Text (PDF) All Versions of this Article: 280/44/36857    most recent M503266200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dalmas, O. Articles by Jault, J.-M. Search for Related Content PubMed PubMed Citation Articles by Dalmas, O. Articles by Jault, J.-M. Social Bookmarking                      What's this?

The Q-loop Disengages from the First Intracellular Loop during the Catalytic Cycle of the Multidrug ABC Transporter BmrA^*

Olivier Dalmas1, Cédric Orelle1, Anne-Emmanuelle Foucher, Christophe Geourjon, Serge Crouzy, Attilio Di Pietro, and Jean-Michel Jault2

From the Institut de Biologie et Chimie des Protéines, Unité Mixte de Recherche 5086 CNRS-UCBL1 and IFR 128, 7 Passage du Vercors, 69367 Lyon Cedex 07, France and Laboratoire de Biophysique Moléculaire et Cellulaire, DRDC, Unité Mixte de Recherche 5090 CNRS/Commissariat à l'Energie Atomique/UJF, Commissariat à l'Energie Atomique 17 Rue des Martyrs, Btiment K, 38054 Grenoble Cedex 9, France

The ATP-binding cassette is the most abundant family of transporters including many medically relevant members and gathers both importers and exporters involved in the transport of a wide variety of substrates. Although three high resolution three-dimensional structures have been obtained for a prototypic exporter, MsbA, two have been subjected to much criticism. Here, conformational changes of BmrA, a multidrug bacterial transporter structurally related to MsbA, have been studied. A three-dimensional model of BmrA, based on the "open" conformation of Escherichia coli MsbA, was probed by simultaneously introducing two cysteine residues, one in the first intracellular loop of the transmembrane domain and the other in the Q-loop of the nucleotide-binding domain (NBD). Intramolecular disulfide bonds could be created in the absence of any effectors, which prevented both drug transport and ATPase activity. Interestingly, addition of ATP/Mg plus vanadate strongly prevented this bond formation in a cysteine double mutant, whereas ATP/Mg alone was sufficient when the ATPase-inactive E504Q mutation was also introduced, in agreement with additional BmrA models where the ATP-binding sites are positioned at the NBD/NBD interface. Furthermore, cross-linking between the two cysteine residues could still be achieved in the presence of ATP/Mg plus vanadate when homobifunctional cross-linkers separated by more than 13 Å were added. Altogether, these results give support to the existence, in the resting state, of a monomeric conformation of BmrA similar to that found within the open MsbA dimer and show that a large motion is required between intracellular loop 1 and the nucleotide-binding domain for the proper functioning of a multidrug ATP-binding cassette transporter.

Received for publication, March 24, 2005 , and in revised form, July 29, 2005.

^* This work was supported by CNRS Grant PGP 2002 (to A. D. P.), a CNRS Young Investigator ATIP Program grant (to J.-M. J.), and ACI IMPBio Grant IMPB027 from the Ministère de la Recherche (to A. D. P. and J.-M. J.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Recipients of fellowships from both the Ministère de la Recherche and Fondation pour la Recherche Médicale.

² To whom correspondence should be addressed. Tel.: 33-4-38-78-31-19; Fax: 33-4-38-78-54-87; E-mail: jean-michel.jault{at}cea.fr.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				M. Grote, E. Bordignon, Y. Polyhach, G. Jeschke, H.-J. Steinhoff, and E. Schneider A Comparative Electron Paramagnetic Resonance Study of the Nucleotide-Binding Domains' Catalytic Cycle in the Assembled Maltose ATP-Binding Cassette Importer Biophys. J., September 15, 2008; 95(6): 2924 - 2938. [Abstract] [Full Text] [PDF]

				A. L. Davidson, E. Dassa, C. Orelle, and J. Chen Structure, Function, and Evolution of Bacterial ATP-Binding Cassette Systems Microbiol. Mol. Biol. Rev., June 1, 2008; 72(2): 317 - 364. [Abstract] [Full Text] [PDF]

				M. L. Daus, M. Grote, P. Muller, M. Doebber, A. Herrmann, H.-J. Steinhoff, E. Dassa, and E. Schneider ATP-driven MalK Dimer Closure and Reopening and Conformational Changes of the "EAA" Motifs Are Crucial for Function of the Maltose ATP-binding Cassette Transporter (MalFGK2) J. Biol. Chem., August 3, 2007; 282(31): 22387 - 22396. [Abstract] [Full Text] [PDF]

				M. Herget, G. Oancea, S. Schrodt, M. Karas, R. Tampe, and R. Abele Mechanism of Substrate Sensing and Signal Transmission within an ABC Transporter: USE OF A TROJAN HORSE STRATEGY J. Biol. Chem., February 9, 2007; 282(6): 3871 - 3880. [Abstract] [Full Text] [PDF]