A specific role for tocopherol and of chemical singlet oxygen quenchers in the maintenance of photosystem II structure and function in Chlamydomonas reinhardtii

FEBS Letters

Holländer-Czytko, Heike¹  Depka, Brigitte²  Trebst, Achim² 

[1] Plant Physiology, Ruhr-University Bochum, D-44780 Bochum, Germany;Plant Biochemistry, Ruhr-University Bochum, D-44780 Bochum, Germany

关键词: D1 protein;    Diphenylamine;    Herbicide;    p-Hydroxyphenylpyruvate dioxygenase;    Photosystem II;    Pyrazolynate;    Singlet oxygen quencher;    Tocopherol;    DPA;    diphenylamine;    HPP;    4-hydroxyphenylpyruvate;    PS II;    photosystem II;   

DOI  :  10.1016/S0014-5793(02)02526-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

α-Tocopherol concentrations were determined at low and high light intensities and compared with the rate of photosynthesis, photosystem II (PS II) and its reaction center D1 protein. Blocking of tocopherol biosynthesis at the 4-hydroxyphenylpyruvate dioxygenase by the herbicide pyrazolynate led to a quick disappearance of α-tocopherol in high light, as well as of PS II activity and the D1 protein. Homogentisic acid rescued all activities. It is concluded that α-tocopherol has a continuous turnover as a scavenger of the singlet oxygen that arises from the quenching by oxygen of the triplet of the PS II reaction center and triggers the degradation of the D1 protein. Thus tocopherols are essential to keep photosynthesis active. We suggest that this is why plants make and need tocopherols. Chemical quenchers of singlet oxygen, notably diphenylamines, completely protect PS II, prevent D1 protein degradation and keep tocopherol levels even at very high light intensities. This supports the notion that ¹O₂ is the intermediate in light triggered D1 protein turnover.

【 授权许可】

Unknown