Destruction of photosystem I iron‐sulfur centers in leaves of Cucumis sativus L. by weak illumination at chilling temperatures

FEBS Letters

Itoh, Shigeru²  Iwaki, Masayo²  Terashima, Ichiro¹  Sonoike, Kintake¹ 

[1] Department of Biology, Faculty of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan;Division of Bioenergetics, National Institute for Basic Biology, Okazaki 444, Japan

关键词: Photoinhibition;    Chilling stress;    Photosynthesis;    Photosystem I;    Reaction center;    Iron-sulfur center;    DCMU;    3-(3;    4-dichlorophenyl)-1;    1-dimethylurea;    PSI;    photosystem I;    PMS;    phenazine methosulfate;    P-700 and A0;    primary electron donor and acceptor chlorophylls;    A1;    the secondary electron acceptor phylloquinone;    FX;    FA;    FB;    iron-sulfur centers;   

DOI  :  10.1016/0014-5793(95)00254-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The activity of photosystem (PS) I in cucumber leaves was selectively inhibited by weak illumination at chilling temperatures with almost no loss of P-700 content and PSII activity. The sites of inactivation in the reducing side of PSI were determined by EPR and flash photolysis. Measurement by EPR showed the destruction of iron-sulfur centers, F_X, F_A and F_B,in parallel with the loss of quantum yield of electron transfer from diaminodurene to NADP⁺. Flash photolysis showed the increases in the triplet states of P-700 and antenna pigments, along with the decrease in the electron transfer from P-700 to F_A/F_B. This indicates the increase in the charge recombination between P-700⁺ and A₀ ⁻. It is concluded that weak-light treatment of cucumber leaves at chilling temperature destroys F_X, F_A and F_B and possibly A₁. This gives the molecular basis for the mechanism of selective PSI photodamage that was recently reported [Sonoike and Terashima (1994) Planta 194, 287–293].

【 授权许可】

Unknown