title: Initial assembly steps of a translocase for folded proteins.
abstract: The so-called Tat (twin-arginine translocation) system transports completely folded proteins across cellular membranes of archaea, prokaryotes and plant chloroplasts. Tat-directed proteins are distinguished by a conserved twin-arginine (RR-) motif in their signal sequences. Many Tat systems are based on the membrane proteins TatA, TatB and TatC, of which TatB and TatC are known to cooperate in binding RR-signal peptides and to form higher-order oligomeric structures. We have now elucidated the fine architecture of TatBC oligomers assembled to form closed intramembrane substrate-binding cavities. The identification of distinct homonymous and heteronymous contacts between TatB and TatC suggest that TatB monomers coalesce into dome-like TatB structures that are surrounded by outer rings of TatC monomers. We also show that these TatBC complexes are approached by TatA protomers through their N-termini, which thereby establish contacts with TatB and membrane-inserted RR-precursors.
authors.affiliation: 1] Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, 79104 Freiburg, Germany [2] Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104 Freiburg, Germany [3] Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Anne-Sophie
authors.initials: AS
authors.lastname: Blümmel
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Haag
authors.affiliation: 1] Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, 79104 Freiburg, Germany [2] Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Eimer
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Müller
authors.affiliation: Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, 79104 Freiburg, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Fröbel
mesh_terms: D000595:Amino Acid Sequence; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017510:Protein Folding; D000069294:Twin-Arginine-Translocation System / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000069294:Twin-Arginine-Translocation System