title: Functional implications of an intermeshing cogwheel-like interaction between TolC and MacA in the action of macrolide-specific efflux pump MacAB-TolC.
abstract: Macrolide-specific efflux pump MacAB-TolC has been identified in diverse gram-negative bacteria including Escherichia coli. The inner membrane transporter MacB requires the outer membrane factor TolC and the periplasmic adaptor protein MacA to form a functional tripartite complex. In this study, we used a chimeric protein containing the tip region of the TolC α-barrel to investigate the role of the TolC α-barrel tip region with regard to its interaction with MacA. The chimeric protein formed a stable complex with MacA, and the complex formation was abolished by substitution at the functionally essential residues located at the MacA α-helical tip region. Electron microscopic study delineated that this complex was made by tip-to-tip interaction between the tip regions of the α-barrels of TolC and MacA, which correlated well with the TolC and MacA complex calculated by molecular dynamics. Taken together, our results demonstrate that the MacA hexamer interacts with TolC in a tip-to-tip manner, and implies the manner by which MacA induces opening of the TolC channel.
authors.affiliation: Department of Manufacturing Pharmacy, Research Institute for Drug Development, Pusan National University, Busan 609-735, Republic of Korea.
authors.forename: Yongbin
authors.initials: Y
authors.lastname: Xu
authors.forename: Saemee
authors.initials: S
authors.lastname: Song
authors.forename: Arne
authors.initials: A
authors.lastname: Moeller
authors.forename: Nahee
authors.initials: N
authors.lastname: Kim
authors.forename: Shunfu
authors.initials: S
authors.lastname: Piao
authors.forename: Se-Hoon
authors.initials: SH
authors.lastname: Sim
authors.forename: Mooseok
authors.initials: M
authors.lastname: Kang
authors.forename: Wookyung
authors.initials: W
authors.lastname: Yu
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Cho
authors.forename: Iksoo
authors.initials: I
authors.lastname: Chang
authors.forename: Kangseok
authors.initials: K
authors.lastname: Lee
authors.forename: Nam-Chul
authors.initials: NC
authors.lastname: Ha
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics / Q000378:metabolism*; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D018942:Macrolides / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; C533519:MacAB protein, E coli; D018942:Macrolides; D026901:Membrane Transport Proteins; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; C073126:tolC protein, E coli