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Hydration-mediated G-protein–coupled receptor activation

The Rhodopsin family of G-protein–coupled receptors (GPCRs) comprises the targets of nearly a third of all pharmaceuticals. Despite structural water present in GPCR X-ray structures, the physiological relevance of these solvent molecules to rhodopsin signaling remains unknown. Here, we show experime...

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Autores principales: Fried, Steven D. E., Hewage, Kushani S. K., Eitel, Anna R., Struts, Andrey V., Weerasinghe, Nipuna, Perera, Suchithranga M. D. C., Brown, Michael F.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9173805/
https://www.ncbi.nlm.nih.gov/pubmed/35584119
http://dx.doi.org/10.1073/pnas.2117349119
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author Fried, Steven D. E.
Hewage, Kushani S. K.
Eitel, Anna R.
Struts, Andrey V.
Weerasinghe, Nipuna
Perera, Suchithranga M. D. C.
Brown, Michael F.
author_facet Fried, Steven D. E.
Hewage, Kushani S. K.
Eitel, Anna R.
Struts, Andrey V.
Weerasinghe, Nipuna
Perera, Suchithranga M. D. C.
Brown, Michael F.
author_sort Fried, Steven D. E.
collection PubMed
description The Rhodopsin family of G-protein–coupled receptors (GPCRs) comprises the targets of nearly a third of all pharmaceuticals. Despite structural water present in GPCR X-ray structures, the physiological relevance of these solvent molecules to rhodopsin signaling remains unknown. Here, we show experimental results consistent with the idea that rhodopsin activation in lipid membranes is coupled to bulk water movements into the protein. To quantify hydration changes, we measured reversible shifting of the metarhodopsin equilibrium due to osmotic stress using an extensive series of polyethylene glycol (PEG) osmolytes. We discovered clear evidence that light activation entails a large influx of bulk water (∼80–100 molecules) into the protein, giving insight into GPCR activation mechanisms. Various size polymer osmolytes directly control rhodopsin activation, in which large solutes are excluded from rhodopsin and dehydrate the protein, favoring the inactive state. In contrast, small osmolytes initially forward shift the activation equilibrium until a quantifiable saturation point is reached, similar to gain-of-function protein mutations. For the limit of increasing osmolyte size, a universal response of rhodopsin to osmotic stress is observed, suggesting it adopts a dynamic, hydrated sponge-like state upon photoactivation. Our results demand a rethinking of the role of water dynamics in modulating various intermediates in the GPCR energy landscape. We propose that besides bound water, an influx of bulk water plays a necessary role in establishing the active GPCR conformation that mediates signaling.
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spelling pubmed-91738052022-11-18 Hydration-mediated G-protein–coupled receptor activation Fried, Steven D. E. Hewage, Kushani S. K. Eitel, Anna R. Struts, Andrey V. Weerasinghe, Nipuna Perera, Suchithranga M. D. C. Brown, Michael F. Proc Natl Acad Sci U S A Biological Sciences The Rhodopsin family of G-protein–coupled receptors (GPCRs) comprises the targets of nearly a third of all pharmaceuticals. Despite structural water present in GPCR X-ray structures, the physiological relevance of these solvent molecules to rhodopsin signaling remains unknown. Here, we show experimental results consistent with the idea that rhodopsin activation in lipid membranes is coupled to bulk water movements into the protein. To quantify hydration changes, we measured reversible shifting of the metarhodopsin equilibrium due to osmotic stress using an extensive series of polyethylene glycol (PEG) osmolytes. We discovered clear evidence that light activation entails a large influx of bulk water (∼80–100 molecules) into the protein, giving insight into GPCR activation mechanisms. Various size polymer osmolytes directly control rhodopsin activation, in which large solutes are excluded from rhodopsin and dehydrate the protein, favoring the inactive state. In contrast, small osmolytes initially forward shift the activation equilibrium until a quantifiable saturation point is reached, similar to gain-of-function protein mutations. For the limit of increasing osmolyte size, a universal response of rhodopsin to osmotic stress is observed, suggesting it adopts a dynamic, hydrated sponge-like state upon photoactivation. Our results demand a rethinking of the role of water dynamics in modulating various intermediates in the GPCR energy landscape. We propose that besides bound water, an influx of bulk water plays a necessary role in establishing the active GPCR conformation that mediates signaling. National Academy of Sciences 2022-05-18 2022-05-24 /pmc/articles/PMC9173805/ /pubmed/35584119 http://dx.doi.org/10.1073/pnas.2117349119 Text en Copyright © 2022 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by-nc-nd/4.0/This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND) (https://creativecommons.org/licenses/by-nc-nd/4.0/) .
spellingShingle Biological Sciences
Fried, Steven D. E.
Hewage, Kushani S. K.
Eitel, Anna R.
Struts, Andrey V.
Weerasinghe, Nipuna
Perera, Suchithranga M. D. C.
Brown, Michael F.
Hydration-mediated G-protein–coupled receptor activation
title Hydration-mediated G-protein–coupled receptor activation
title_full Hydration-mediated G-protein–coupled receptor activation
title_fullStr Hydration-mediated G-protein–coupled receptor activation
title_full_unstemmed Hydration-mediated G-protein–coupled receptor activation
title_short Hydration-mediated G-protein–coupled receptor activation
title_sort hydration-mediated g-protein–coupled receptor activation
topic Biological Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9173805/
https://www.ncbi.nlm.nih.gov/pubmed/35584119
http://dx.doi.org/10.1073/pnas.2117349119
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