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Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response
Free-living microorganisms are subjected to drastic changes in osmolarity. To avoid lysis under sudden osmotic down-shock, bacteria quickly expel small metabolites through the tension-activated channels MscL, MscS, and MscK. We examined five chromosomal knockout strains, ∆mscL, ∆mscS, a double knock...
Autores principales: | , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Rockefeller University Press
2023
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10082366/ https://www.ncbi.nlm.nih.gov/pubmed/37022337 http://dx.doi.org/10.1085/jgp.202213168 |
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author | Moller, Elissa Britt, Madolyn Schams, Anthony Cetuk, Hannah Anishkin, Andriy Sukharev, Sergei |
author_facet | Moller, Elissa Britt, Madolyn Schams, Anthony Cetuk, Hannah Anishkin, Andriy Sukharev, Sergei |
author_sort | Moller, Elissa |
collection | PubMed |
description | Free-living microorganisms are subjected to drastic changes in osmolarity. To avoid lysis under sudden osmotic down-shock, bacteria quickly expel small metabolites through the tension-activated channels MscL, MscS, and MscK. We examined five chromosomal knockout strains, ∆mscL, ∆mscS, a double knockout ∆mscS ∆mscK, and a triple knockout ∆mscL ∆mscS ∆mscK, in comparison to the wild-type parental strain. Stopped-flow experiments confirmed that both MscS and MscL mediate fast osmolyte release and curb cell swelling, but osmotic viability assays indicated that they are not equivalent. MscS alone was capable of rescuing the cell population, but in some strains, MscL did not rescue and additionally became toxic in the absence of both MscS and MscK. Furthermore, MscS was upregulated in the ∆mscL strain, suggesting either a crosstalk between the two genes/proteins or the influence of cell mechanics on mscS expression. The data shows that for the proper termination of the permeability response, the high-threshold (MscL) and the low-threshold (MscS/MscK) channels must act sequentially. In the absence of low-threshold channels, at the end of the release phase, MscL should stabilize membrane tension at around 10 mN/m. Patch-clamp protocols emulating the tension changes during the release phase indicated that the non-inactivating MscL, residing at its own tension threshold, flickers and produces a protracted leakage. The MscS/MscK population, when present, stays open at this stage to reduce tension below the MscL threshold and silence the large channel. When MscS reaches its own threshold, it inactivates and thus ensures proper termination of the hypoosmotic permeability response. This functional interplay between the high- and low-threshold channels is further supported by the compromised osmotic survival of bacteria expressing non-inactivating MscS mutants. |
format | Online Article Text |
id | pubmed-10082366 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-100823662023-10-06 Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response Moller, Elissa Britt, Madolyn Schams, Anthony Cetuk, Hannah Anishkin, Andriy Sukharev, Sergei J Gen Physiol Article Free-living microorganisms are subjected to drastic changes in osmolarity. To avoid lysis under sudden osmotic down-shock, bacteria quickly expel small metabolites through the tension-activated channels MscL, MscS, and MscK. We examined five chromosomal knockout strains, ∆mscL, ∆mscS, a double knockout ∆mscS ∆mscK, and a triple knockout ∆mscL ∆mscS ∆mscK, in comparison to the wild-type parental strain. Stopped-flow experiments confirmed that both MscS and MscL mediate fast osmolyte release and curb cell swelling, but osmotic viability assays indicated that they are not equivalent. MscS alone was capable of rescuing the cell population, but in some strains, MscL did not rescue and additionally became toxic in the absence of both MscS and MscK. Furthermore, MscS was upregulated in the ∆mscL strain, suggesting either a crosstalk between the two genes/proteins or the influence of cell mechanics on mscS expression. The data shows that for the proper termination of the permeability response, the high-threshold (MscL) and the low-threshold (MscS/MscK) channels must act sequentially. In the absence of low-threshold channels, at the end of the release phase, MscL should stabilize membrane tension at around 10 mN/m. Patch-clamp protocols emulating the tension changes during the release phase indicated that the non-inactivating MscL, residing at its own tension threshold, flickers and produces a protracted leakage. The MscS/MscK population, when present, stays open at this stage to reduce tension below the MscL threshold and silence the large channel. When MscS reaches its own threshold, it inactivates and thus ensures proper termination of the hypoosmotic permeability response. This functional interplay between the high- and low-threshold channels is further supported by the compromised osmotic survival of bacteria expressing non-inactivating MscS mutants. Rockefeller University Press 2023-04-06 /pmc/articles/PMC10082366/ /pubmed/37022337 http://dx.doi.org/10.1085/jgp.202213168 Text en © 2023 Moller et al. https://creativecommons.org/licenses/by-nc-sa/4.0/http://www.rupress.org/terms/This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms/). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 International license, as described at https://creativecommons.org/licenses/by-nc-sa/4.0/). |
spellingShingle | Article Moller, Elissa Britt, Madolyn Schams, Anthony Cetuk, Hannah Anishkin, Andriy Sukharev, Sergei Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title | Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title_full | Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title_fullStr | Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title_full_unstemmed | Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title_short | Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response |
title_sort | mechanosensitive channel mscs is critical for termination of the bacterial hypoosmotic permeability response |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10082366/ https://www.ncbi.nlm.nih.gov/pubmed/37022337 http://dx.doi.org/10.1085/jgp.202213168 |
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