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

DOI: 10.1038/s41467-022-34137-4 DOI Help

Authors: Volha U. Chukhutsina (Imperial College London) , James M. Baxter (Imperial College London) , Alisia Fadini (Imperial College London) , Rhodri M. Morgan (Imperial College London) , Matthew A. Pope (Imperial College London) , Karim Maghlaoui (Imperial College London) , Christian M. Orr (Diamond Light Source) , Armin Wagner (Diamond Light Source) , Jasper J. Van Thor (Imperial College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Communications , VOL 13

State: Published (Approved)
Published: October 2022
Diamond Proposal Number(s): 17221

Open Access Open Access

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.

Journal Keywords: Light responses; Non-photochemical quenching; Photobiology; X-ray crystallography

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I03-Macromolecular Crystallography , I04-Macromolecular Crystallography , I23-Long wavelength MX

Added On: 31/10/2022 10:22


Discipline Tags:

Biochemistry Chemistry Structural biology Biophysics Life Sciences & Biotech

Technical Tags:

Diffraction Macromolecular Crystallography (MX)