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Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion

Proteins are co-translationally inserted into the bacterial plasma membrane via the SecYEG translocon by lateral release of hydrophobic transmembrane segments into the phospholipid bilayer. The trigger for lateral opening of the translocon is not known. Here we monitor lateral opening by photo-induc...

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Autores principales: Ge, Yan, Draycheva, Albena, Bornemann, Thomas, Rodnina, Marina V., Wintermeyer, Wolfgang
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Pub. Group 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4218953/
https://www.ncbi.nlm.nih.gov/pubmed/25314960
http://dx.doi.org/10.1038/ncomms6263
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author Ge, Yan
Draycheva, Albena
Bornemann, Thomas
Rodnina, Marina V.
Wintermeyer, Wolfgang
author_facet Ge, Yan
Draycheva, Albena
Bornemann, Thomas
Rodnina, Marina V.
Wintermeyer, Wolfgang
author_sort Ge, Yan
collection PubMed
description Proteins are co-translationally inserted into the bacterial plasma membrane via the SecYEG translocon by lateral release of hydrophobic transmembrane segments into the phospholipid bilayer. The trigger for lateral opening of the translocon is not known. Here we monitor lateral opening by photo-induced electron transfer (PET) between two fluorophores attached to the two SecY helices at the rim of the gate. In the resting translocon, the fluorescence is quenched, consistent with a closed conformation. Ribosome binding to the translocon diminishes PET quenching, indicating opening of the gate. The effect is larger with ribosomes exposing hydrophobic transmembrane segments and vanishes at low temperature. We propose a temperature-dependent dynamic equilibrium between closed and open conformations of the translocon that is shifted towards partially and fully open by ribosome binding and insertion of a hydrophobic peptide, respectively. The combined effects of ribosome and peptide binding allow for co-translational membrane insertion of successive transmembrane segments.
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spelling pubmed-42189532014-11-06 Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion Ge, Yan Draycheva, Albena Bornemann, Thomas Rodnina, Marina V. Wintermeyer, Wolfgang Nat Commun Article Proteins are co-translationally inserted into the bacterial plasma membrane via the SecYEG translocon by lateral release of hydrophobic transmembrane segments into the phospholipid bilayer. The trigger for lateral opening of the translocon is not known. Here we monitor lateral opening by photo-induced electron transfer (PET) between two fluorophores attached to the two SecY helices at the rim of the gate. In the resting translocon, the fluorescence is quenched, consistent with a closed conformation. Ribosome binding to the translocon diminishes PET quenching, indicating opening of the gate. The effect is larger with ribosomes exposing hydrophobic transmembrane segments and vanishes at low temperature. We propose a temperature-dependent dynamic equilibrium between closed and open conformations of the translocon that is shifted towards partially and fully open by ribosome binding and insertion of a hydrophobic peptide, respectively. The combined effects of ribosome and peptide binding allow for co-translational membrane insertion of successive transmembrane segments. Nature Pub. Group 2014-10-15 /pmc/articles/PMC4218953/ /pubmed/25314960 http://dx.doi.org/10.1038/ncomms6263 Text en Copyright © 2014, Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved. http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Ge, Yan
Draycheva, Albena
Bornemann, Thomas
Rodnina, Marina V.
Wintermeyer, Wolfgang
Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title_full Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title_fullStr Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title_full_unstemmed Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title_short Lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
title_sort lateral opening of the bacterial translocon on ribosome binding and signal peptide insertion
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4218953/
https://www.ncbi.nlm.nih.gov/pubmed/25314960
http://dx.doi.org/10.1038/ncomms6263
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