Proton flow through the ATP synthase in chloroplasts regulates the distribution of light energy between PS I and PS II

FEBS Letters

Braun, Gur¹  Malkin, Shmuel¹  Evron, Yoav¹  Avron, Mordhay¹ 

[1] Department of Biochemistry, Welzmann Institute of Science, Rehovot 76100, Israel

关键词: Photosystem I;    Photosystem II;    ATP synthase;    Proton flow;    Light excitation imbalance;    Chlorophyll fluorescence;    PS;    photosystem;    ATP;    adenosine tri-phosphate;    ADP;    adenosine di-phosphate;    MeV;    methylviologen;    DCCD;    N;    N′-dicyclohexyl carbodiimide;    TTX;    tentoxin;   

DOI  :  10.1016/0014-5793(91)80203-F

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The involvement of ATP synthase in the imbalance between the photoactivities of PS I and PS II under light-limiting conditions, was examined in broken lettuce chloroplasts using modulated fluorimetry. The imbalance, in favor of PS II, was minimal and roughly constant between pH 6.5–7.3 (ratio of PS II/PS I activities about 1.1), and maximal at pH 8.5 (ratio of PS II/PS I activities about 1.4). This increase was strongly inhibited by a treatment of the chloroplasts with the CF₀ ATP synthase inhibitor DCCD, but unaffected by the CF₁ ATPase inhibitor, tentoxin. However, tentoxin plus ADP-P, did inhibit the high pH-induced increase imbalance. These results, when considered with the previous results on the effect of high pH on proton flux through the ATP synthase, suggest that the rate of such proton flow controls the imbalance between the two photosystems. It is possible that there is an in vivo fine-tuning regulating mechanism of the photosystems imbalance via the opening and closing of proton gradient dissipation through the ATP synthase. This mechanism may help alleviate photoinhibitory damage.

【 授权许可】

Unknown