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Elastic network model‐based normal mode analysis reveals the conformational couplings in the tripartite AcrAB‐TolC multidrug efflux complex
Author(s) -
Wang Beibei,
Weng Jingwei,
Fan Kangnian,
Wang Wenning
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.23143
Subject(s) - trimer , efflux , allosteric regulation , transmembrane domain , biophysics , transmembrane protein , chemistry , docking (animal) , membrane , biology , biochemistry , dimer , receptor , medicine , nursing , organic chemistry
The AcrAB‐TolC drug efflux system, energized by proton movement down the transmembrane electrochemical gradient, is responsible for the resistance of the organism to a wide range of drugs. Experimental data suggest functional roles of each part of the assembly, but the detailed working mechanism of this machinery remains elusive. We used elastic network‐based normal mode analysis (NMA) to explore the conformational dynamics of the AcrAB‐TolC complex. The intrinsic flexibilities of the pore domain in AcrB monomer conform to the previously proposed three‐step functionally rotating mechanism for asymmetric AcrB trimer. Conformational couplings across monomers in the AcrB trimer were observed, and the coupling between the transmembrane domain and the other parts of AcrB are strengthened through trimeric assembly. In the tripartite AcrAB‐TolC assembly obtained through molecular docking, concerted motions were observed not only at the direct contact interfaces between various components but also between distant parts of the whole complex. The presence of AcrA was shown to significantly strengthen the motional couplings between AcrB and TolC. Overall, NMA revealed an allosteric network in the AcAB‐TolC efflux system, which provides hints to our understanding of its detailed working mechanism. Proteins 2011; © 2011 Wiley‐Liss, Inc.