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High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane

Permeabilization of the outer mitochondrial membrane by pore‐forming Bcl2 proteins is a crucial step for the induction of apoptosis. Despite a large set of data suggesting global conformational changes within pro‐apoptotic Bak during pore formation, high‐resolution structural details in a membrane e...

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Autores principales: Sperl, Laura E, Rührnößl, Florian, Schiller, Anita, Haslbeck, Martin, Hagn, Franz
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8521305/
https://www.ncbi.nlm.nih.gov/pubmed/34523144
http://dx.doi.org/10.15252/embj.2020107159
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author Sperl, Laura E
Rührnößl, Florian
Schiller, Anita
Haslbeck, Martin
Hagn, Franz
author_facet Sperl, Laura E
Rührnößl, Florian
Schiller, Anita
Haslbeck, Martin
Hagn, Franz
author_sort Sperl, Laura E
collection PubMed
description Permeabilization of the outer mitochondrial membrane by pore‐forming Bcl2 proteins is a crucial step for the induction of apoptosis. Despite a large set of data suggesting global conformational changes within pro‐apoptotic Bak during pore formation, high‐resolution structural details in a membrane environment remain sparse. Here, we used NMR and HDX‐MS (Hydrogen deuterium exchange mass spectrometry) in lipid nanodiscs to gain important high‐resolution structural insights into the conformational changes of Bak at the membrane that are dependent on a direct activation by BH3‐only proteins. Furthermore, we determined the first high‐resolution structure of the Bak transmembrane helix. Upon activation, α‐helix 1 in the soluble domain of Bak dissociates from the protein and adopts an unfolded and dynamic potentially membrane‐bound state. In line with this finding, comparative protein folding experiments with Bak and anti‐apoptotic BclxL suggest that α‐helix 1 in Bak is a metastable structural element contributing to its pro‐apoptotic features. Consequently, mutagenesis experiments aimed at stabilizing α‐helix 1 yielded Bak variants with delayed pore‐forming activity. These insights will contribute to a better mechanistic understanding of Bak‐mediated membrane permeabilization.
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spelling pubmed-85213052021-10-29 High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane Sperl, Laura E Rührnößl, Florian Schiller, Anita Haslbeck, Martin Hagn, Franz EMBO J Articles Permeabilization of the outer mitochondrial membrane by pore‐forming Bcl2 proteins is a crucial step for the induction of apoptosis. Despite a large set of data suggesting global conformational changes within pro‐apoptotic Bak during pore formation, high‐resolution structural details in a membrane environment remain sparse. Here, we used NMR and HDX‐MS (Hydrogen deuterium exchange mass spectrometry) in lipid nanodiscs to gain important high‐resolution structural insights into the conformational changes of Bak at the membrane that are dependent on a direct activation by BH3‐only proteins. Furthermore, we determined the first high‐resolution structure of the Bak transmembrane helix. Upon activation, α‐helix 1 in the soluble domain of Bak dissociates from the protein and adopts an unfolded and dynamic potentially membrane‐bound state. In line with this finding, comparative protein folding experiments with Bak and anti‐apoptotic BclxL suggest that α‐helix 1 in Bak is a metastable structural element contributing to its pro‐apoptotic features. Consequently, mutagenesis experiments aimed at stabilizing α‐helix 1 yielded Bak variants with delayed pore‐forming activity. These insights will contribute to a better mechanistic understanding of Bak‐mediated membrane permeabilization. John Wiley and Sons Inc. 2021-09-15 2021-10-18 /pmc/articles/PMC8521305/ /pubmed/34523144 http://dx.doi.org/10.15252/embj.2020107159 Text en © 2021 The Authors. Published under the terms of the CC BY NC ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ (https://creativecommons.org/licenses/by-nc-nd/4.0/) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
spellingShingle Articles
Sperl, Laura E
Rührnößl, Florian
Schiller, Anita
Haslbeck, Martin
Hagn, Franz
High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title_full High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title_fullStr High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title_full_unstemmed High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title_short High‐resolution analysis of the conformational transition of pro‐apoptotic Bak at the lipid membrane
title_sort high‐resolution analysis of the conformational transition of pro‐apoptotic bak at the lipid membrane
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8521305/
https://www.ncbi.nlm.nih.gov/pubmed/34523144
http://dx.doi.org/10.15252/embj.2020107159
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