title: Structural analysis of a signal peptide inside the ribosome tunnel by DNP MAS NMR.
abstract: Proteins are synthesized in cells by ribosomes and, in parallel, prepared for folding or targeting. While ribosomal protein synthesis is progressing, the nascent chain exposes amino-terminal signal sequences or transmembrane domains that mediate interactions with specific interaction partners, such as the signal recognition particle (SRP), the SecA-adenosine triphosphatase, or the trigger factor. These binding events can set the course for folding in the cytoplasm and translocation across or insertion into membranes. A distinction of the respective pathways depends largely on the hydrophobicity of the recognition sequence. Hydrophobic transmembrane domains stabilize SRP binding, whereas less hydrophobic signal sequences, typical for periplasmic and outer membrane proteins, stimulate SecA binding and disfavor SRP interactions. In this context, the formation of helical structures of signal peptides within the ribosome was considered to be an important factor. We applied dynamic nuclear polarization magic-angle spinning nuclear magnetic resonance to investigate the conformational states of the disulfide oxidoreductase A (DsbA) signal peptide stalled within the exit tunnel of the ribosome. Our results suggest that the nascent chain comprising the DsbA signal sequence adopts an extended structure in the ribosome with only minor populations of helical structure.
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.; Freie Universität Berlin, Fachbereich BCP, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Sascha
authors.initials: S
authors.lastname: Lange
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.
authors.forename: W Trent
authors.identifier: 0000-0003-4111-8868
authors.initials: WT
authors.lastname: Franks
authors.affiliation: Center for Molecular Biology of the University of Heidelberg (ZMBH), Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.; DKFZ-ZMBH Alliance and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany.
authors.forename: Nandhakishore
authors.initials: N
authors.lastname: Rajagopalan
authors.affiliation: Center for Molecular Biology of the University of Heidelberg (ZMBH), Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.; DKFZ-ZMBH Alliance and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany.
authors.forename: Kristina
authors.identifier: 0000-0002-1465-6882
authors.initials: K
authors.lastname: Döring
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.; Freie Universität Berlin, Fachbereich BCP, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Michel A
authors.initials: MA
authors.lastname: Geiger
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.; Freie Universität Berlin, Fachbereich BCP, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Arne
authors.initials: A
authors.lastname: Linden
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.
authors.forename: Barth-Jan
authors.initials: BJ
authors.lastname: van Rossum
authors.affiliation: Center for Molecular Biology of the University of Heidelberg (ZMBH), Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.; DKFZ-ZMBH Alliance and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Kramer
authors.affiliation: Center for Molecular Biology of the University of Heidelberg (ZMBH), Im Neuenheimer Feld 282, Heidelberg D-69120, Germany.; DKFZ-ZMBH Alliance and German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, Heidelberg D-69120, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Bukau
authors.affiliation: Leibniz Institut für Molekulare Pharmakologie im Forschungsverbund Berlin e.V. (FMP), Campus Berlin-Buch, Robert-Roessle-Str. 10, D-13125 Berlin, Germany.; Freie Universität Berlin, Fachbereich BCP, Takustr. 3, 14195 Berlin, Germany.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Oschkinat
mesh_terms: D000595:Amino Acid Sequence; D008279:Magnetic Resonance Imaging / Q000379:methods*; D021382:Protein Sorting Signals / Q000235:genetics; D011994:Recombinant Proteins; D012270:Ribosomes / Q000737:chemistry* / Q000235:genetics
chemical_list: D021382:Protein Sorting Signals; D011994:Recombinant Proteins
keywords: MAS NMR; Protein structure; co-translational folding; dynamic nuclear polarisation; ribosome; signal peptide