5TV0

crystal structure and light induced structural changes in orange carotenoid protein bound with 3 'OH echinenone

5TV0 の概要

• エントリーDOI: 10.2210/pdb5tv0/pdb
• 関連するPDBエントリー: 5TUW 5TUX
• 分子名称: Orange carotenoid-binding protein, GLYCEROL, (3'R)-3'-hydroxy-beta,beta-caroten-4-one, ... (4 entities in total)
• 機能のキーワード: photoprotection, photoreceptor, dynamic crystallography, carotenoid binding protein
• 由来する生物種: Synechocystis sp. (strain PCC 6803 / Kazusa)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 36172.43

構造登録者

Yang, X.,Bandara, S.,Ren, Z. (登録日: 2016-11-07, 公開日: 2017-06-07, 最終更新日: 2023-10-04)

主引用文献

Bandara, S.,Ren, Z.,Lu, L.,Zeng, X.,Shin, H.,Zhao, K.H.,Yang, X.
Photoactivation mechanism of a carotenoid-based photoreceptor.
Proc. Natl. Acad. Sci. U.S.A., 114:6286-6291, 2017

PubMed Abstract: Photoprotection is essential for efficient photosynthesis. Cyanobacteria have evolved a unique photoprotective mechanism mediated by a water-soluble carotenoid-based photoreceptor known as orange carotenoid protein (OCP). OCP undergoes large conformational changes in response to intense blue light, and the photoactivated OCP facilitates dissipation of excess energy via direct interaction with allophycocyanins at the phycobilisome core. However, the structural events leading up to the OCP photoactivation remain elusive at the molecular level. Here we present direct observations of light-induced structural changes in OCP captured by dynamic crystallography. Difference electron densities between the dark and illuminated states reveal widespread and concerted atomic motions that lead to altered protein-pigment interactions, displacement of secondary structures, and domain separation. Based on these crystallographic observations together with site-directed mutagenesis, we propose a molecular mechanism for OCP light perception, in which the photochemical property of a conjugated carbonyl group is exploited. We hypothesize that the OCP photoactivation starts with keto-enol tautomerization of the essential 4-keto group in the carotenoid, which disrupts the strong hydrogen bonds between the bent chromophore and the protein moiety. Subsequent structural changes trapped in the crystal lattice offer a high-resolution glimpse of the initial molecular events as OCP begins to transition from the orange-absorbing state to the active red-absorbing state.

PubMed: 28559328
DOI: 10.1073/pnas.1700956114

実験手法

X-RAY DIFFRACTION (1.648 Å)