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Quantifying proton-induced membrane polarization in single biomimetic giant vesicles

Proton gradients are utilized by cells to power the transport activity of many membrane proteins. Synthetic cells, such as proteo-giant unilamellar vesicles, offer an advanced approach for studying the functionality of membrane proteins in isolation. However, understanding of protein-based transport...

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Detalles Bibliográficos
Autores principales: Tivony, Ran, Fletcher, Marcus, Keyser, Ulrich F.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Biophysical Society 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9279353/
https://www.ncbi.nlm.nih.gov/pubmed/35643630
http://dx.doi.org/10.1016/j.bpj.2022.05.041
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author Tivony, Ran
Fletcher, Marcus
Keyser, Ulrich F.
author_facet Tivony, Ran
Fletcher, Marcus
Keyser, Ulrich F.
author_sort Tivony, Ran
collection PubMed
description Proton gradients are utilized by cells to power the transport activity of many membrane proteins. Synthetic cells, such as proteo-giant unilamellar vesicles, offer an advanced approach for studying the functionality of membrane proteins in isolation. However, understanding of protein-based transport in vitro requires accurate measurements of proton flux and its accompanying electrochemical gradient across the lipid bilayer. We present an approach to directly quantify the flux of protons across single cell-sized lipid vesicles under modulated electrochemical gradients. Our measurements reveal the corresponding association between proton permeation and transmembrane potential development and its relation to the chemical nature of the conjugated anion (base). In the case of formic acid, we showed that, out of the total amount of permeated protons, a fraction of ≈0.2 traverse the lipid bilayer as H(+), with the rest (≈0.8) in the form of a neutral acid. For strong acids (HCl or HNO(3)), proton permeation was governed by translocation of H(+). Accordingly, a larger proton motive force (pmf) was generated for strong acids ([Formula: see text] mV) relative to formic acid ([Formula: see text] mV). We anticipate that our approach will guide the development of protein-based transport driven by proton gradient in artificial cell models and enable a deeper understanding of how vital acids, such as fatty acids, amino acids, bile acids, and carboxylic acid-containing drugs, traverse the lipid bilayer.
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spelling pubmed-92793532023-06-21 Quantifying proton-induced membrane polarization in single biomimetic giant vesicles Tivony, Ran Fletcher, Marcus Keyser, Ulrich F. Biophys J Articles Proton gradients are utilized by cells to power the transport activity of many membrane proteins. Synthetic cells, such as proteo-giant unilamellar vesicles, offer an advanced approach for studying the functionality of membrane proteins in isolation. However, understanding of protein-based transport in vitro requires accurate measurements of proton flux and its accompanying electrochemical gradient across the lipid bilayer. We present an approach to directly quantify the flux of protons across single cell-sized lipid vesicles under modulated electrochemical gradients. Our measurements reveal the corresponding association between proton permeation and transmembrane potential development and its relation to the chemical nature of the conjugated anion (base). In the case of formic acid, we showed that, out of the total amount of permeated protons, a fraction of ≈0.2 traverse the lipid bilayer as H(+), with the rest (≈0.8) in the form of a neutral acid. For strong acids (HCl or HNO(3)), proton permeation was governed by translocation of H(+). Accordingly, a larger proton motive force (pmf) was generated for strong acids ([Formula: see text] mV) relative to formic acid ([Formula: see text] mV). We anticipate that our approach will guide the development of protein-based transport driven by proton gradient in artificial cell models and enable a deeper understanding of how vital acids, such as fatty acids, amino acids, bile acids, and carboxylic acid-containing drugs, traverse the lipid bilayer. The Biophysical Society 2022-06-21 2022-05-28 /pmc/articles/PMC9279353/ /pubmed/35643630 http://dx.doi.org/10.1016/j.bpj.2022.05.041 Text en © 2022 Biophysical Society. https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Articles
Tivony, Ran
Fletcher, Marcus
Keyser, Ulrich F.
Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title_full Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title_fullStr Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title_full_unstemmed Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title_short Quantifying proton-induced membrane polarization in single biomimetic giant vesicles
title_sort quantifying proton-induced membrane polarization in single biomimetic giant vesicles
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9279353/
https://www.ncbi.nlm.nih.gov/pubmed/35643630
http://dx.doi.org/10.1016/j.bpj.2022.05.041
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