Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH

FEBS Letters

Mohanty, Narendranath¹  Yamamoto, Harry Y.¹  Gilmore, Adam M.¹ 

[1] University of Hawaii, Department of Plant Molecular Physiology, St. John 503, 3190 Maile Way, Honolulu, Hawaii 96822, USA

关键词: Nonradiative energy dissipation;    Xanthophyll-cycle function;    Violaxanthin deepoxidation;    Xanthophyll-cycle localization;    Carotenoid function;    Anth;    antheraxanthin;    Chl;    chlorophyll;    DTT;    dithiothreitol;    Fo;    minimum fluorescence under de-energized state with PSII traps fully open;    FM and F′M;    maximum fluorescence at de-energized and energized states;    respectively;    FV;    variable fluorescence (FM—FO);    NPQ;    non-photochemical quenching of chlorophyll a fluorescence;    SVN;    Stern-Volmer calculation of NPQ;    Viol;    violaxanthin;    Zeax;    zeaxanthin;   

DOI  :  10.1016/0014-5793(94)00784-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The xanthophyll cycle apparently aids the photoprotection of photosystem II by regulating the nonradiative dissipation of excess absorbed light energy as heat. However, it is a controversial question whether the resulting nonphotochemical quenching is soley dependent on xanthophyll cycle activity or not. The xanthophyll cycle consists of two enzymic reactions, namely deepoxidation of the diepoxide violaxanthin to the epoxide-free zeaxanthin and the much slower, reverse process of epoxidation. While deepoxidation requires a transthylakoid pH gradient (ΔpH), epoxidation can proceed irrespective of a ΔpH. Herein, we compared the extent and kinetics of deepoxidation and epoxidation to the changes in fluorescence in the presence of a light-induced thylakoid ΔpH. We show that epoxidation reverses fluorescence quenching without affecting thylakoid ΔpH. These results suggest that epoxidase activity reverses quenching by removing deepoxidized xanthophyll cycle pigments from quenching complexes and converting them to a nonquenching form. The transmembrane organization of the xanthophyll cycle influences the localization and the availability of deepoxidized xanthophylls is to support nonphotochemical quenching capacity. The results confirm the view that rapidly reversible nonphotochemical quenching is dependent on deepoxidized xanthophyll.

【 授权许可】

Unknown