3CQN

Crystal Structure of the Lipocalin domain of Violaxanthin de-epoxidase (VDE) at pH7

3CQN の概要

• エントリーDOI: 10.2210/pdb3cqn/pdb
• 関連するPDBエントリー: 3CQR
• 分子名称: Violaxanthin de-epoxidase, chloroplast (2 entities in total)
• 機能のキーワード: lipocalin, enzyme, de-epoxidase, xanthophyll cycle, non photochemical quenching, npq, violaxanthin, antheraxanthin, zeaxanthin, ph dependant transition, chloroplast, membrane, oxidoreductase, thylakoid, transit peptide
• 由来する生物種: Arabidopsis thaliana (Mouse-ear cress)
• 細胞内の位置: Plastid, chloroplast thylakoid membrane; Peripheral membrane protein; Lumenal side (By similarity): Q39249
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 42686.91

構造登録者

Arnoux, P.,Morosinotto, T.,Pignol, D. (登録日: 2008-04-03, 公開日: 2009-04-21, 最終更新日: 2024-04-03)

主引用文献

Arnoux, P.,Morosinotto, T.,Saga, G.,Bassi, R.,Pignol, D.
A structural basis for the pH-dependent xanthophyll cycle in Arabidopsis thaliana.
Plant Cell, 21:2036-2044, 2009

PubMed Abstract: Plants adjust their photosynthetic activity to changing light conditions. A central regulation of photosynthesis depends on the xanthophyll cycle, in which the carotenoid violaxanthin is converted into zeaxanthin in strong light, thus activating the dissipation of the excess absorbed energy as heat and the scavenging of reactive oxygen species. Violaxanthin deepoxidase (VDE), the enzyme responsible for zeaxanthin synthesis, is activated by the acidification of the thylakoid lumen when photosynthetic electron transport exceeds the capacity of assimilatory reactions: at neutral pH, VDE is a soluble and inactive enzyme, whereas at acidic pH, it attaches to the thylakoid membrane where it binds its violaxanthin substrate. VDE also uses ascorbate as a cosubstrate with a pH-dependent Km that may reflect a preference for ascorbic acid. We determined the structures of the central lipocalin domain of VDE (VDEcd) at acidic and neutral pH. At neutral pH, VDEcd is monomeric with its active site occluded within a lipocalin barrel. Upon acidification, the barrel opens up and the enzyme appears as a dimer. A channel linking the two active sites of the dimer can harbor the entire carotenoid substrate and thus may permit the parallel deepoxidation of the two violaxanthin beta-ionone rings, making VDE an elegant example of the adaptation of an asymmetric enzyme to its symmetric substrate.

PubMed: 19638474
DOI: 10.1105/tpc.109.068007

実験手法

X-RAY DIFFRACTION (2 Å)