title: Conserved Omp85 lid-lock structure and substrate recognition in FhaC.
abstract: Omp85 proteins mediate translocation of polypeptide substrates across and into cellular membranes. They share a common architecture comprising substrate-interacting POTRA domains, a C-terminal 16-stranded β-barrel pore and two signature motifs located on the inner barrel wall and at the tip of the extended L6 loop. The observation of two distinct conformations of the L6 loop in the available Omp85 structures previously suggested a functional role of conformational changes in L6 in the Omp85 mechanism. Here we present a 2.5 Å resolution structure of a variant of the Omp85 secretion protein FhaC, in which the two signature motifs interact tightly and form the conserved 'lid lock'. Reanalysis of previous structural data shows that L6 adopts the same, conserved resting state position in all available Omp85 structures. The FhaC variant structure further reveals a competitive mechanism for the regulation of substrate binding mediated by the linker to the N-terminal plug helix H1.
authors.affiliation: Biozentrum, University of Basel, Klingelbergstr. 70, Basel 4056, Switzerland.
authors.forename: Timm
authors.initials: T
authors.lastname: Maier
authors.affiliation: CNRS UMR8576, Unité Glycobiologie Structurale et Fonctionnelle, Villeneuve d'Ascq 59658, France.|Univ. Lille Nord de France, Lille, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Clantin
authors.affiliation: Biozentrum, University of Basel, Klingelbergstr. 70, Basel 4056, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Gruss
authors.affiliation: CNRS UMR8576, Unité Glycobiologie Structurale et Fonctionnelle, Villeneuve d'Ascq 59658, France.|Univ. Lille Nord de France, Lille, France.
authors.forename: Frédérique
authors.initials: F
authors.lastname: Dewitte
authors.affiliation: Univ. Lille Nord de France, Lille, France.|Institut Pasteur de Lille, Center for Infection and Immunity, Lille 59021, France.|CNRS UMR8204, Lille 59046, France.|INSERM U1019, Lille 59045, France.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Delattre
authors.affiliation: Univ. Lille Nord de France, Lille, France.|Institut Pasteur de Lille, Center for Infection and Immunity, Lille 59021, France.|CNRS UMR8204, Lille 59046, France.|INSERM U1019, Lille 59045, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Jacob-Dubuisson
authors.affiliation: Biozentrum, University of Basel, Klingelbergstr. 70, Basel 4056, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Hiller
authors.affiliation: CNRS UMR8576, Unité Glycobiologie Structurale et Fonctionnelle, Villeneuve d'Ascq 59658, France.|Univ. Lille Nord de France, Lille, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Villeret
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014961:X-Ray Diffraction
chemical_list: D001425:Bacterial Outer Membrane Proteins; C503914:BamA protein, E coli; D029968:Escherichia coli Proteins