7ZSG

Structure of Orange Carotenoid Protein with canthaxanthin bound after 1 minute of illumination

Summary for 7ZSG

• Entry DOI: 10.2210/pdb7zsg/pdb
• Related: 7ZSF 7ZSH 7ZSI 7ZSJ
• Descriptor: Orange carotenoid-binding protein, beta,beta-carotene-4,4'-dione, GLYCEROL, ... (6 entities in total)
• Functional Keywords: photoreceptor, carotenoid, photosynthesis
• Biological source: Synechocystis
• Total number of polymer chains: 1
• Total formula weight: 36627.32

Authors

Chukhutsina, V.U.,Baxter, J.M.,Fadini, A.,Morgan, R.M.,Pope, M.A.,Maghlaoui, K.,Orr, C.,Wagner, A.,van Thor, J.J. (deposition date: 2022-05-06, release date: 2022-11-09, Last modification date: 2024-01-31)

Primary citation

Chukhutsina, V.U.,Baxter, J.M.,Fadini, A.,Morgan, R.M.,Pope, M.A.,Maghlaoui, K.,Orr, C.M.,Wagner, A.,van Thor, J.J.
Light activation of Orange Carotenoid Protein reveals bicycle-pedal single-bond isomerization.
Nat Commun, 13:6420-6420, 2022

PubMed 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.

PubMed: 36307413
DOI: 10.1038/s41467-022-34137-4

Experimental method

X-RAY DIFFRACTION (1.39 Å)