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The SecA motor generates mechanical force during protein translocation

The Sec translocon moves proteins across lipid bilayers in all cells. The Sec channel enables passage of unfolded proteins through the bacterial plasma membrane, driven by the cytosolic ATPase SecA. Whether SecA generates mechanical force to overcome barriers to translocation posed by structured sub...

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Autores principales: Gupta, Riti, Toptygin, Dmitri, Kaiser, Christian M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393111/
https://www.ncbi.nlm.nih.gov/pubmed/32732903
http://dx.doi.org/10.1038/s41467-020-17561-2
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author Gupta, Riti
Toptygin, Dmitri
Kaiser, Christian M.
author_facet Gupta, Riti
Toptygin, Dmitri
Kaiser, Christian M.
author_sort Gupta, Riti
collection PubMed
description The Sec translocon moves proteins across lipid bilayers in all cells. The Sec channel enables passage of unfolded proteins through the bacterial plasma membrane, driven by the cytosolic ATPase SecA. Whether SecA generates mechanical force to overcome barriers to translocation posed by structured substrate proteins is unknown. Here, we kinetically dissect Sec-dependent translocation by monitoring translocation of a folded substrate protein with tunable stability at high time resolution. We find that substrate unfolding constitutes the rate-limiting step during translocation. Using single-molecule force spectroscopy, we also define the response of the protein to mechanical force. Relating the kinetic and force measurements reveals that SecA generates at least 10 piconewtons of mechanical force to actively unfold translocating proteins, comparable to cellular unfoldases. Combining biochemical and single-molecule measurements thus allows us to define how the SecA motor ensures efficient and robust export of proteins that contain stable structure.
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spelling pubmed-73931112020-08-12 The SecA motor generates mechanical force during protein translocation Gupta, Riti Toptygin, Dmitri Kaiser, Christian M. Nat Commun Article The Sec translocon moves proteins across lipid bilayers in all cells. The Sec channel enables passage of unfolded proteins through the bacterial plasma membrane, driven by the cytosolic ATPase SecA. Whether SecA generates mechanical force to overcome barriers to translocation posed by structured substrate proteins is unknown. Here, we kinetically dissect Sec-dependent translocation by monitoring translocation of a folded substrate protein with tunable stability at high time resolution. We find that substrate unfolding constitutes the rate-limiting step during translocation. Using single-molecule force spectroscopy, we also define the response of the protein to mechanical force. Relating the kinetic and force measurements reveals that SecA generates at least 10 piconewtons of mechanical force to actively unfold translocating proteins, comparable to cellular unfoldases. Combining biochemical and single-molecule measurements thus allows us to define how the SecA motor ensures efficient and robust export of proteins that contain stable structure. Nature Publishing Group UK 2020-07-30 /pmc/articles/PMC7393111/ /pubmed/32732903 http://dx.doi.org/10.1038/s41467-020-17561-2 Text en © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Gupta, Riti
Toptygin, Dmitri
Kaiser, Christian M.
The SecA motor generates mechanical force during protein translocation
title The SecA motor generates mechanical force during protein translocation
title_full The SecA motor generates mechanical force during protein translocation
title_fullStr The SecA motor generates mechanical force during protein translocation
title_full_unstemmed The SecA motor generates mechanical force during protein translocation
title_short The SecA motor generates mechanical force during protein translocation
title_sort seca motor generates mechanical force during protein translocation
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393111/
https://www.ncbi.nlm.nih.gov/pubmed/32732903
http://dx.doi.org/10.1038/s41467-020-17561-2
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