7EKR

The crystal structure of Orange carotenoid binding protein 1 (OCP1)

Summary for 7EKR

• Entry DOI: 10.2210/pdb7ekr/pdb
• Descriptor: Orange carotenoid protein, beta,beta-carotene-4,4'-dione (3 entities in total)
• Functional Keywords: cyanobacteria, keto-carotenoids, cysteins, photosynthesis
• Biological source: Gloeocapsa sp. PCC 7513
• Total number of polymer chains: 2
• Total formula weight: 79757.34

Authors

Song, J.J.,Yoon, J. (deposition date: 2021-04-06, release date: 2022-04-13, Last modification date: 2023-11-29)

Primary citation

Han, M.H.,Yang, H.W.,Yoon, J.,Villafani, Y.,Song, J.Y.,Pan, C.H.,Park, K.,Cho, Y.,Song, J.J.,Kim, S.J.,Park, Y.I.,Park, J.
Color-Tuning Mechanism of the Lit Form of Orange Carotenoid Protein.
Mol.Cells, 46:513-525, 2023

PubMed Abstract: Orange carotenoid protein (OCP) of photosynthetic cyanobacteria binds to ketocarotenoids noncovalently and absorbs excess light to protect the host organism from light-induced oxidative damage. Herein, we found that mutating valine 40 in the α3 helix of sp. PCC 7513 (GOCP1) resulted in blue- or red-shifts of 6-20 nm in the absorption maxima of the lit forms. We analyzed the origins of absorption maxima shifts by integrating X-ray crystallography, homology modeling, molecular dynamics simulations, and hybrid quantum mechanics/molecular mechanics calculations. Our analysis suggested that the single residue mutations alter the polar environment surrounding the bound canthaxanthin, thereby modulating the degree of charge transfer in the photoexcited state of the chromophore. Our integrated investigations reveal the mechanism of color adaptation specific to OCPs and suggest a design principle for color-specific photoswitches.

PubMed: 37587751
DOI: 10.14348/molcells.2023.2186

Experimental method

X-RAY DIFFRACTION (2.17 Å)