Towards an interpretation of 13C chemical shifts in bathorhodopsin, a functional intermediate of a G-protein coupled receptor
Towards an interpretation of 13C chemical shifts in bathorhodopsin, a functional intermediate of a G-protein coupled receptor
Photoisomerization of the membrane-bound light receptor protein rhodopsin leads to an energy-rich photostate called bathorhodopsin, which may be trapped at temperatures of 120 K or lower. We recently studied bathorhodopsin by low-temperature solid-state NMR, using in situ illumination of the sample in a purpose-built NMR probe. In this way we acquired 13C chemical shifts along the retinylidene chain of the chromophore. Here we compare these results with the chemical shifts of the dark state chromophore in rhodopsin, as well as with the chemical shifts of retinylidene model compounds in solution. An earlier solid-state NMR study of bathorhodopsin found only small changes in the 13C chemical shifts upon isomerization, suggesting only minor perturbations of the electronic structure in the isomerized retinylidene chain. This is at variance with our recent measurements which show much larger perturbations of the 13C chemical shifts. Here we present a tentative interpretation of our NMR results involving an increased charge delocalization inside the polyene chain of the bathorhodopsin chromophore. Our results suggest that the bathochromic shift of bathorhodopsin is due to modified electrostatic interactions between the chromophore and the binding pocket, whereas both electrostatic interactions and torsional strain are involved in the energy storage mechanism of bathorhodopsin.
double-quantum solid-state nmr, bathorhodopsin, retinylidene psb, 13c chemical shift, energy storage, bathochromic shift
1350-1357
Gansmüller, A.
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Concistrè, M.
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McLean, N.
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Johannessen, O.G.
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Marín-Montesinos, I.
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Bovee-Geurts, P.H.M.
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Verdegem, P.
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Lugtenburg, J.
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Brown, R.C.D.
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DeGrip, W.J.
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Levitt, M.H.
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June 2009
Gansmüller, A.
de349280-f72c-40bf-ad79-c25872862f3a
Concistrè, M.
ec95c9d4-ecb8-4c28-a464-8c3adba9e86d
McLean, N.
3250113c-28d4-499b-8282-e54c3d8a9862
Johannessen, O.G.
799ccc8c-a2e7-4305-a03a-2dc9f42564ef
Marín-Montesinos, I.
d60ebd82-86df-49a8-b0a5-1abbc2550b62
Bovee-Geurts, P.H.M.
46c26df2-56a8-42f8-a154-d953e53e1fdf
Verdegem, P.
eb03ab19-3b7b-4dc0-a9fd-015580faa1d3
Lugtenburg, J.
d1624cf1-129a-46f1-a2c8-b651898e15b8
Brown, R.C.D.
21ce697a-7c3a-480e-919f-429a3d8550f5
DeGrip, W.J.
3fe658dc-e4cd-4d05-9771-417fd462ae72
Levitt, M.H.
bcc5a80a-e5c5-4e0e-9a9a-249d036747c3
Gansmüller, A., Concistrè, M., McLean, N., Johannessen, O.G., Marín-Montesinos, I., Bovee-Geurts, P.H.M., Verdegem, P., Lugtenburg, J., Brown, R.C.D., DeGrip, W.J. and Levitt, M.H.
(2009)
Towards an interpretation of 13C chemical shifts in bathorhodopsin, a functional intermediate of a G-protein coupled receptor.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 1788 (6), .
(doi:10.1016/j.bbamem.2009.02.018).
(PMID:19265671)
Abstract
Photoisomerization of the membrane-bound light receptor protein rhodopsin leads to an energy-rich photostate called bathorhodopsin, which may be trapped at temperatures of 120 K or lower. We recently studied bathorhodopsin by low-temperature solid-state NMR, using in situ illumination of the sample in a purpose-built NMR probe. In this way we acquired 13C chemical shifts along the retinylidene chain of the chromophore. Here we compare these results with the chemical shifts of the dark state chromophore in rhodopsin, as well as with the chemical shifts of retinylidene model compounds in solution. An earlier solid-state NMR study of bathorhodopsin found only small changes in the 13C chemical shifts upon isomerization, suggesting only minor perturbations of the electronic structure in the isomerized retinylidene chain. This is at variance with our recent measurements which show much larger perturbations of the 13C chemical shifts. Here we present a tentative interpretation of our NMR results involving an increased charge delocalization inside the polyene chain of the bathorhodopsin chromophore. Our results suggest that the bathochromic shift of bathorhodopsin is due to modified electrostatic interactions between the chromophore and the binding pocket, whereas both electrostatic interactions and torsional strain are involved in the energy storage mechanism of bathorhodopsin.
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Published date: June 2009
Keywords:
double-quantum solid-state nmr, bathorhodopsin, retinylidene psb, 13c chemical shift, energy storage, bathochromic shift
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Local EPrints ID: 178391
URI: http://eprints.soton.ac.uk/id/eprint/178391
ISSN: 0304-4165
PURE UUID: cb8c3c90-e25e-4a9f-a27a-1a705c583f71
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Date deposited: 24 Mar 2011 14:53
Last modified: 22 Feb 2025 02:43
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Contributors
Author:
A. Gansmüller
Author:
M. Concistrè
Author:
N. McLean
Author:
O.G. Johannessen
Author:
I. Marín-Montesinos
Author:
P.H.M. Bovee-Geurts
Author:
P. Verdegem
Author:
J. Lugtenburg
Author:
W.J. DeGrip
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