title: Assembling the Tat protein translocase.
abstract: The twin-arginine protein translocation system (Tat) transports folded proteins across the bacterial cytoplasmic membrane and the thylakoid membranes of plant chloroplasts. The Tat transporter is assembled from multiple copies of the membrane proteins TatA, TatB, and TatC. We combine sequence co-evolution analysis, molecular simulations, and experimentation to define the interactions between the Tat proteins ofEscherichia coliat molecular-level resolution. In the TatBC receptor complex the transmembrane helix of each TatB molecule is sandwiched between two TatC molecules, with one of the inter-subunit interfaces incorporating a functionally important cluster of interacting polar residues. Unexpectedly, we find that TatA also associates with TatC at the polar cluster site. Our data provide a structural model for assembly of the active Tat translocase in which substrate binding triggers replacement of TatB by TatA at the polar cluster site. Our work demonstrates the power of co-evolution analysis to predict protein interfaces in multi-subunit complexes.
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Felicity
authors.initials: F
authors.lastname: Alcock
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Stansfeld
authors.affiliation: Department of Chemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Hajra
authors.initials: H
authors.lastname: Basit
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, United Kingdom.
authors.forename: Johann
authors.initials: J
authors.lastname: Habersetzer
authors.affiliation: Department of Chemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Matthew Ab
authors.initials: MA
authors.lastname: Baker
authors.affiliation: Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, United Kingdom.
authors.forename: Tracy
authors.initials: T
authors.lastname: Palmer
authors.affiliation: Department of Chemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Mark I
authors.identifier: 0000-0002-5692-8313
authors.initials: MI
authors.lastname: Wallace
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
authors.forename: Ben C
authors.identifier: 0000-0001-9685-4067
authors.initials: BC
authors.lastname: Berks
mesh_terms: D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008954:Models, Biological; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C499697:TatA protein, E coli; C473116:TatB protein, E coli; C461379:TatC protein, E coli
keywords: E. coli; Tat protein transport; biochemistry; biophysics; membrane protein; sequence co-evolution; structural biology; twin-arginine