title: The inverse autotransporter intimin exports its passenger domain via a hairpin intermediate.
abstract: Autotransporter proteins comprise a large family of virulence factors that consist of a β-barrel translocation unit and an extracellular effector or passenger domain. The β-barrel anchors the protein to the outer membrane of Gram-negative bacteria and facilitates the transport of the passenger domain onto the cell surface. By inserting an epitope tag into the N terminus of the passenger domain of the inverse autotransporter intimin, we generated a mutant defective in autotransport. Using this stalled mutant, we could show that (i) at the time point of stalling, the β-barrel appears folded; (ii) the stalled autotransporter is associated with BamA and SurA; (iii) the stalled intimin is decorated with large amounts of SurA; (iv) the stalled autotransporter is not degraded by periplasmic proteases; and (v) inverse autotransporter passenger domains are translocated by a hairpin mechanism. Our results suggest a function for the BAM complex not only in insertion and folding of the β-barrel but also for passenger translocation.
authors.affiliation: From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and.
authors.forename: Philipp
authors.initials: P
authors.lastname: Oberhettinger
authors.affiliation: the Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway.
authors.forename: Jack C
authors.initials: JC
authors.lastname: Leo
authors.affiliation: the Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway.
authors.forename: Dirk
authors.initials: D
authors.lastname: Linke
authors.affiliation: From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and.
authors.forename: Ingo B
authors.initials: IB
authors.lastname: Autenrieth
authors.affiliation: From the Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Strasse 6, 72076 Tübingen, Germany and monika.schuetz@med.uni-tuebingen.de.
authors.forename: Monika S
authors.initials: MS
authors.lastname: Schütz
mesh_terms: D018829:Adhesins, Bacterial / Q000737:chemistry / Q000502:physiology*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000737:chemistry; D000939:Epitopes / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D018832:Molecular Chaperones / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010447:Peptide Hydrolases / Q000737:chemistry; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013499:Surface Properties
chemical_list: D018829:Adhesins, Bacterial; D003432:Cross-Linking Reagents; D000939:Epitopes; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; C073819:eaeA protein, E coli; D010447:Peptide Hydrolases
keywords: Adhesin; Bacterial Pathogenesis; Intimin, Type Ve Secretion, Autotransporter, beta Barrel Protein, Hairpin; Membrane Protein; Microbial Pathogenesis; Microbiology; Outer Membrane