title: Conserved features in TamA enable interaction with TamB to drive the activity of the translocation and assembly module.
abstract: The biogenesis of membranes from constituent proteins and lipids is a fundamental aspect of cell biology. In the case of proteins assembled into bacterial outer membranes, an overarching question concerns how the energy required for protein insertion and folding is accessed at this remote location of the cell. The translocation and assembly module (TAM) is a nanomachine that functions in outer membrane biogenesis and virulence in diverse bacterial pathogens. Here we demonstrate the interactions through which TamA and TamB subunits dock to bridge the periplasm, and unite the outer membrane aspects to the inner membrane of the bacterial cell. We show that specific functional features in TamA have been conserved through evolution, including residues surrounding the lateral gate and an extensive surface of the POTRA domains. Analysis by nuclear magnetic resonance spectroscopy and small angle X-ray scattering document the characteristic structural features of these POTRA domains and demonstrate rigidity in solution. Quartz crystal microbalance measurements pinpoint which POTRA domain specifically docks the TamB subunit of the nanomachine. We speculate that the POTRA domain of TamA functions as a lever arm in order to drive the activity of the TAM, assembling proteins into bacterial outer membranes.
authors.affiliation: 1] Department of Microbiology, Monash University, Clayton 3800, Australia [2] Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
authors.forename: Joel
authors.initials: J
authors.lastname: Selkrig
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Belousoff
authors.affiliation: Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Headey
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia.
authors.forename: Eva
authors.initials: E
authors.lastname: Heinz
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia.
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiota
authors.affiliation: 1] Department of Microbiology, Monash University, Clayton 3800, Australia [2] Department of Materials Engineering, Monash University, Clayton 3800, Australia.
authors.forename: Hsin-Hui
authors.initials: HH
authors.lastname: Shen
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
authors.forename: Simone A
authors.initials: SA
authors.lastname: Beckham
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia.
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Bamert
authors.affiliation: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Minh-Duy
authors.initials: MD
authors.lastname: Phan
authors.affiliation: Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schembri
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Australia.
authors.forename: Matthew C J
authors.initials: MC
authors.lastname: Wilce
authors.affiliation: Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville 3052, Australia.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Scanlon
authors.affiliation: Department of Microbiology &Immunology, University of Melbourne, Parkville 3052, Australia.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Strugnell
authors.affiliation: Department of Microbiology, Monash University, Clayton 3800, Australia.
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000502:physiology; D017124:Conserved Sequence; D019143:Evolution, Molecular; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary
chemical_list: D001425:Bacterial Outer Membrane Proteins