title: Allosteric transitions of the maltose transporter studied by an elastic network model.
abstract: The maltose transporter from Escherichia coli is one of the ATP-binding cassette (ABC) transporters that utilize the energy from ATP hydrolysis to translocate substrates across cellular membranes. Until 2011, three crystal structures have been determined for maltose transporter at different states in the process of transportation. Here, based on these crystal structures, the allosteric pathway from the resting state (inward-facing) to the catalytic intermediate state (outward-facing) is studied by applying an adaptive anisotropic network model. The results suggest that the allosteric transitions proceed in a coupled way. The closing of the nucleotide-binding domains occurs first, and subsequently this conformational change is propagated to the transmembrane domains (TMD) via the EAA and EAS loops, and then to the maltose-binding protein, which facilitates the translocation of the maltose. It is also found that there exist nonrigid-body and asymmetric movements in the TMD. The cytoplasmic gate may only play the role of allosteric propagation during the transition from the pretranslocation to outward-facing states. In addition, the results show that the movment of the helical subdomain towards the RecA-like subdomain mainly occurs in the earlier stages of the transition. These results can provide some insights into the understanding of the mechanism of ABC transporters.
authors.affiliation: College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China.
authors.forename: Chun Hua
authors.initials: CH
authors.lastname: Li
authors.forename: Yong Xiao
authors.initials: YX
authors.lastname: Yang
authors.forename: Ji Guo
authors.initials: JG
authors.lastname: Su
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Jian Jun
authors.initials: JJ
authors.lastname: Tan
authors.forename: Xiao Yi
authors.initials: XY
authors.lastname: Zhang
authors.forename: Cun Xin
authors.initials: CX
authors.lastname: Wang
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000378:metabolism; D000465:Algorithms; D016880:Anisotropy; D001665:Binding Sites; D001692:Biological Transport; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008320:Maltose / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D019897:Periplasm / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D018528:ATP-Binding Cassette Transporters; D029968:Escherichia coli Proteins; C461599:maltose transport system, E coli; D008320:Maltose
keywords: allosteric transitions; elastic network model; maltose transporter