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Light activation of Orange Carotenoid Protein reveals bicycle-pedal single-bond isomerization.

Light activation of Orange Carotenoid Protein reveals bicycle-pedal single-bond isomerization.

Authors :
Chukhutsina VU
Baxter JM
Fadini A
Morgan RM
Pope MA
Maghlaoui K
Orr CM
Wagner A
van Thor JJ
Source :
Nature communications [Nat Commun] 2022 Oct 28; Vol. 13 (1), pp. 6420. Date of Electronic Publication: 2022 Oct 28.
Publication Year :
2022

Abstract

Orange Carotenoid protein (OCP) is the only known photoreceptor which uses carotenoid for its activation. It is found exclusively in cyanobacteria, where it functions to control light-harvesting of the photosynthetic machinery. However, the photochemical reactions and structural dynamics of this unique photosensing process are not yet resolved. We present time-resolved crystal structures at second-to-minute delays under bright illumination, capturing the early photoproduct and structures of the subsequent reaction intermediates. The first stable photoproduct shows concerted isomerization of C9'-C8' and C7'-C6' single bonds in the bicycle-pedal (s-BP) manner and structural changes in the N-terminal domain with minute timescale kinetics. These are followed by a thermally-driven recovery of the s-BP isomer to the dark state carotenoid configuration. Structural changes propagate to the C-terminal domain, resulting, at later time, in the H-bond rupture of the carotenoid keto group with protein residues. Solution FTIR and UV/Vis spectroscopy support the single bond isomerization of the carotenoid in the s-BP manner and subsequent thermal structural reactions as the basis of OCP photoreception.<br /> (© 2022. The Author(s).)

Details

Language :
English
ISSN :
2041-1723
Volume :
13
Issue :
1
Database :
MEDLINE
Journal :
Nature communications
Publication Type :
Academic Journal
Accession number :
36307413
Full Text :
https://doi.org/10.1038/s41467-022-34137-4