title: Allosteric signalling in the outer membrane translocation domain of PapC usher.
abstract: PapC ushers are outer-membrane proteins enabling assembly and secretion of P pili in uropathogenic E. coli. Their translocation domain is a large β-barrel occluded by a plug domain, which is displaced to allow the translocation of pilus subunits across the membrane. Previous studies suggested that this gating mechanism is controlled by a β-hairpin and an α-helix. To investigate the role of these elements in allosteric signal communication, we developed a method combining evolutionary and molecular dynamics studies of the native translocation domain and mutants lacking the β-hairpin and/or the α-helix. Analysis of a hybrid residue interaction network suggests distinct regions (residue 'communities') within the translocation domain (especially around β12-β14) linking these elements, thereby modulating PapC gating. Antibiotic sensitivity and electrophysiology experiments on a set of alanine-substitution mutants confirmed functional roles for four of these communities. This study illuminates the gating mechanism of PapC ushers and its importance in maintaining outer-membrane permeability.
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, United Kingdom.
authors.forename: Irene
authors.initials: I
authors.lastname: Farabella
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, United States.
authors.forename: Thieng
authors.initials: T
authors.lastname: Pham
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, United States.
authors.forename: Nadine S
authors.initials: NS
authors.lastname: Henderson
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, United Kingdom.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Geibel
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, United Kingdom.
authors.forename: Gilles
authors.initials: G
authors.lastname: Phan
authors.affiliation: Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, United States.
authors.forename: David G
authors.initials: DG
authors.lastname: Thanassi
authors.affiliation: Department of Biology and Biochemistry, University of Houston, Houston, United States.
authors.forename: Anne H
authors.initials: AH
authors.lastname: Delcour
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, United Kingdom.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Waksman
authors.affiliation: Institute of Structural and Molecular Biology, Birkbeck College and University College London, London, United Kingdom.
authors.forename: Maya
authors.initials: M
authors.lastname: Topf
mesh_terms: D000409:Alanine / Q000737:chemistry / Q000378:metabolism; D000494:Allosteric Regulation; D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002463:Cell Membrane Permeability; D004917:Erythromycin / Q000494:pharmacology; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008564:Membrane Potentials; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D018272:Porins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D015398:Signal Transduction; D056689:Uropathogenic Escherichia coli / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014640:Vancomycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D029968:Escherichia coli Proteins; D018272:Porins; D021122:Protein Subunits; C111243:atpG protein, E coli; D004917:Erythromycin; D014640:Vancomycin; D000409:Alanine
keywords: E. coli; biophysics; dynamics; evolution; outer membrane protein; structural biology; structure