Determination of the spatial arrangement of polypeptides in photosystem II by photo-and oxygen radical-induced protein cross-linking.

目前研究的初始目标是通过化学交叉链接和轻诱导交叉链接方法的使用来识别未知的多态性，这些多态性被定位在反应中心与D1蛋白结合在一起。However，在研究过程中，我们发现了一种金属蛋白酶FtsH位于光电系统II的核心复合体附近。然后，我们专注于我们的努力，以澄清FtsH蛋白在光电系统II中的作用。以下结果得到了：1.通过化学和光电化学交叉链接实验，我们找到了与D1蛋白质的FtsH蛋白质反应。这些数据很好，就像膜分裂数据强烈地认为FtsH蛋白可以识别出颗粒状的D1蛋白. 2.通过适度的热处理（40 ° C，30分钟），对螺旋藻状甲状腺素，D1蛋白被清除。我们发现FtsH对热损伤D1蛋白的清除负有责任.3.使用氰化物突变体损伤FtsH蛋白，我们确认，突变细胞中热损伤或光损伤D1蛋白没有被移除，还有生长和氧气的方法--进化的活动被明显地抑制了，所有这些结果都强烈地认为FtsH蛋白质是对光电系统II下质量控制的必要条件。光和热的压力。

The initial purpose of the present research was to identify unknown polypeptides that are located closely to the reaction-center binding D1 protein in photosystem II by the use of chemical cross-linking and light-induced cross-linking methods. However, during the course of the study, we found that a metalloprotease FtsH is located near the core complex of photosystem II. We then have focused our efforts to clarify the roles of the FtsH protease in photosystem II. The following results were obtained.1.By chemical and photochemical cross-linking experiments, we found that the FtsH protease reacts with the D1 protein. These data as well as the membrane fractionation data strongly suggest that the FtsH protease can recognize the photodamaged D1 protein at the grana thylakoids.2.By moderate heat treatment (40゜C for 30 min) on spinach thylakoids, the D1 protein was cleaved. We found that the FtsH is responsible for the cleavage of the heat-damaged D1 protein.3.Using a cyanobacterial mutant lacking the FtsH protease, we confirmed that the the heat-or light-damaged D1 protein in the mutant cells is not removed, and thereby the growth and oxygen-evolving activity are significantly inhibited.All these results strongly suggest that the FtsH protease is essential for the quality control of photosystem II under light and heat stresses.