Research output: Contribution to journal › Article › peer-review
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.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 119, No. 21, e2117349119, 18.05.2022.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Hydration-mediated G-protein-coupled receptor activation
AU - Fried, Steven D.E.
AU - Hewage, Kushani S.K.
AU - Eitel, Anna R.
AU - Struts, Andrey V.
AU - Weerasinghe, Nipuna
AU - Perera, Suchithranga M.D.C.
AU - Brown, Michael F.
N1 - Publisher Copyright: Copyright © 2022 the Author(s).
PY - 2022/5/18
Y1 - 2022/5/18
N2 - 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.
AB - 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.
KW - GPCR
KW - osmotic stress
KW - rhodopsin
KW - sponge model
KW - structural water
KW - Rhodopsin/metabolism
KW - Receptors, G-Protein-Coupled/metabolism
KW - Protein Conformation
KW - Solvents/chemistry
KW - Water/chemistry
UR - http://www.scopus.com/inward/record.url?scp=85130767720&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/56cebc3e-4f15-35f4-9c0d-97103697a216/
U2 - 10.1073/pnas.2117349119
DO - 10.1073/pnas.2117349119
M3 - Article
C2 - 35584119
AN - SCOPUS:85130767720
VL - 119
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 21
M1 - e2117349119
ER -
ID: 97504044