title: Elastic network model-based normal mode analysis reveals the conformational couplings in the tripartite AcrAB-TolC multidrug efflux complex.
abstract: 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.
authors: Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry and Institute of Biomedical Sciences, Fudan University, Shanghai, People's Republic of China.
authors: Beibei
authors: B
authors: Wang
authors: Jingwei
authors: J
authors: Weng
authors: Kangnian
authors: K
authors: Fan
authors: Wenning
authors: W
authors: Wang
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D017433:Protein Structure, Secondary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008074:Lipoproteins; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; C083497:AcrA protein, E coli; C083496:AcrB protein, E coli; C073126:tolC protein, E coli