title: Early contacts between substrate proteins and TatA translocase component in twin-arginine translocation.
abstract: Twin-arginine translocation (Tat) is a unique protein transport pathway in bacteria, archaea, and plastids. It mediates the transmembrane transport of fully folded proteins, which harbor a consensus twin-arginine motif in their signal sequences. In Gram-negative bacteria and plant chloroplasts, three membrane proteins, named TatA, TatB, and TatC, are required to enable Tat translocation. Available data suggest that TatA assembles into oligomeric pore-like structures that might function as the protein conduit across the lipid bilayer. Using site-specific photo-cross-linking, we have investigated the molecular environment of TatA under resting and translocating conditions. We find that monomeric TatA is an early interacting partner of functionally targeted Tat substrates. This interaction with TatA likely precedes translocation of Tat substrates and is influenced by the proton-motive force. It strictly depends on the presence of TatB and TatC, the latter of which is shown to make contacts with the transmembrane helix of TatA.
authors: Institute of Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Zellforschung (ZBMZ), University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
authors: Julia
authors: J
authors: Fröbel
authors: Institute of Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Zellforschung (ZBMZ), University of Freiburg, 79104 Freiburg, Germany; Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
authors: Patrick
authors: P
authors: Rose
authors: Institute of Biochemistry and Molecular Biology, Zentrum für Biochemie und Molekulare Zellforschung (ZBMZ), University of Freiburg, 79104 Freiburg, Germany. Electronic address: matthias.mueller@biochemie.uni-freiburg.de.
authors: Matthias
authors: M
authors: Müller
mesh_terms: D001120:Arginine / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D026901:Membrane Transport Proteins / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D017510:Protein Folding; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D021381:Protein Transport
chemical_list: D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; C499697:TatA protein, E coli; C473116:TatB protein, E coli; C461379:TatC protein, E coli; D001120:Arginine