title: Dynamic interplay of membrane-proximal POTRA domain and conserved loop L6 in Omp85 transporter FhaC.
abstract: Omp85 transporters mediate protein insertion into, or translocation across, membranes. They have a conserved architecture, with POTRA domains that interact with substrate proteins, a 16-stranded transmembrane β barrel, and an extracellular loop, L6, folded back in the barrel pore. Here using electrophysiology, in vivo biochemical approaches and electron paramagnetic resonance, we show that the L6 loop of the Omp85 transporter FhaC changes conformation and modulates channel opening. Those conformational changes involve breaking the conserved interaction between the tip of L6 and the inner β-barrel wall. The membrane-proximal POTRA domain also exchanges between several conformations, and the binding of FHA displaces this equilibrium. We further demonstrate a dynamic, physical communication between the POTRA domains and L6, which must take place via the β barrel. Our findings thus link all three essential components of Omp85 transporters and indicate that they operate in a concerted fashion in the transport cycle.
authors.affiliation: Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.|Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.|CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.|INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Guérin
authors.affiliation: PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR9214, 371 av. G. Giraud, 34295, Montpellier cedex 05, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Saint
authors.affiliation: Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.|Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.|CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.|INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Baud
authors.affiliation: PhyMedExp, University of Montpellier, INSERM U1046, CNRS UMR9214, 371 av. G. Giraud, 34295, Montpellier cedex 05, France.
authors.forename: Albano C
authors.initials: AC
authors.lastname: Meli
authors.affiliation: Aix-Marseille Université, CNRS, BIP (UMR 7281), 31 chemin J. Aiguier, 13402, Marseille cedex 20, France.
authors.forename: Emilien
authors.initials: E
authors.lastname: Etienne
authors.affiliation: Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.|Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.|CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.|INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Locht
authors.affiliation: Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.|CNRS UMR8516, Bat. C4, 59658, Villeneuve d'Ascq, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Vezin
authors.affiliation: Institut Pasteur de Lille, CIIL, 1 rue Calmette, 59019, Lille Cedex, France.|Université de Lille, 1 rue G. Lefebvre, 59000, Lille, France.|CNRS UMR 8204, 2 rue des Canonniers, 59046, Lille, France.|INSERM U1019, 6 rue Pr. Laguesse, 59045, Lille, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Jacob-Dubuisson
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001886:Bordetella pertussis / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; C503914:BamA protein, E coli; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; C098052:fhaC protein, Bordetella pertussis