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Epoxidation of zeaxanthin and antheraxanthin reverses non‐photochemical quenching of photosystem II chlorophyll a fluorescence in the presence of trans‐thylakoid ΔpH
Author(s) -
Gilmore Adam M.,
Mohanty Narendranath,
Yamamoto Harry Y.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00784-5
Subject(s) - violaxanthin , xanthophyll , antheraxanthin , photosystem ii , quenching (fluorescence) , zeaxanthin , photoprotection , photochemistry , thylakoid , non photochemical quenching , chemistry , chlorophyll fluorescence , photoinhibition , photosynthesis , lutein , biochemistry , chloroplast , fluorescence , carotenoid , physics , quantum mechanics , gene
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.