Degration and removal of the proteins in photosystem II during photoinhibition

当植物受到强光照射时，光合作用发生光抑制。光抑制的靶细胞是光系统II。本研究以菠菜PS II膜、PS II核心样品和披衣细胞为材料，研究了光系统II反应中心结合蛋白D1在光胁迫下的损伤、降解和恢复过程。结果表明：（1）光系统II的一个33 kDa的外源蛋白调节D1蛋白的损伤降解步骤。33-kDa蛋白降低D1的聚集，同时增强D1的降解。(2)活性氧分子不仅参与D1的还原侧光抑制，而且参与供体侧光抑制。(3)在强光照射下，FTIR检测到PS II的构象发生了较大的变化，但在过氧化氢处理下，PS II的结构没有发生明显的变化。

When plants are illuminated with strong light, photoinhibition of photosynthesis takes place. The target of photoinhibition is photosystem II.In the present study, damage, degradation and recovery processes of the reaction-center binding D1 protein in photosystem II during light stress were studied with spinach PS II membranes, PS II core samples and Chlamydomonas cells. The results obtained are as follows ;(1) An extrinsic 33 kDa protein of photosystem II regulates the damage-degradation step of the D1 protein. The 33-kDa protein decreases the aggregation of D1 and at the same time enhances the degradation of D1.(2) Active oxygen molecules are involved in the degradation of D1 not only in the reducing-side photoinhibition, but also in the donor-side photoinhibition.(3) A large conformational change cn be detected by FTIR under the illumination of the PS II samples with strong light, but no siggnificant structural changes in PS II was found in hydrogen peroxide treatment of the PS II samples.