Light activation of Orange Carotenoid Protein reveals bicycle-pedal single-bond isomerization
File(s)
Published version
Author(s)
Type
Journal Article
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.
Date Issued
2022-10-28
Date Acceptance
2022-10-14
Citation
Nature Communications, 2022, 13 (1), pp.1-14
ISSN
2041-1723
Publisher
Nature Research
Start Page
1
End Page
14
Journal / Book Title
Nature Communications
Volume
13
Issue
1
Copyright Statement
© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
License URL
Sponsor
The Leverhulme Trust
Commission of the European Communities
Identifier
https://www.nature.com/articles/s41467-022-34137-4
Grant Number
RPG-2018-372
839389
Subjects
Isomerism
Bicycling
Bacterial Proteins
Carotenoids
Light
Carotenoids
Bacterial Proteins
Isomerism
Light
Bicycling
Publication Status
Published
Article Number
6420
Date Publish Online
2022-10-28