| Autor: |
Chukhutsina, Volha U., Baxter, James M., Fadini, Alisia, Morgan, Rhodri M., Pope, Matthew A., Maghlaoui, Karim, Orr, Christian M., Wagner, Armin, van Thor, Jasper J. |
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| Zdroj: |
Nature Communications; 10/28/2022, Vol. 13 Issue 1, p1-14, 14p |
| Abstrakt: |
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. Orange Carotenoid protein (OCP) is the only photoreceptor with a carotenoid for sensing. Here, the authors report crystal structures of the early OCP photoproduct, suggesting that photo-sensing involves single bond isomerization. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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