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Aggregation of the reaction cenfer-binding protein of photosystem 11 under light stress and cell death

光系统11反应中心结合蛋白在光应激和细胞死亡下的聚集

基本信息

批准号：
18570042
负责人：
YAMAMOTO Yasusi
金额：
$ 2.53万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18570042/
关键词：
Photosystem II D1 protein Protein degradation Protein aggregation Heat stress Light stress Quality control mechanism Photosynthesis 活性酸素

项目摘要

Photosystem II (PSII) is the target of various abiotic stresses including excess visible light and high temperature. The reaction center Dl protein of PSII is damaged easily under these stresses and the damaged protein is either degraded by a specific protease(s) or forms aggregates with the nearby polypeptides such as D2 protein or CP43. In the present study, we analyzed the details of the degradation and aggregation pathways of the light-or heat-damaged Dl protein, using spinach thylakoids and the cyanobacterium Synechocystis PCC6803. The main points are as follows:(1) When spinach thylakoids were heat-stressed (40℃ for 30 min), the D1 protein was damaged and the damaged D1 protein was degraded by FtsH proteases. We demonstrated the action of FtsH proteases by the solubilization and reconstitution experiments of FtsH.(2) We found that heat stress induces reactive oxygen species, such as singlet oxygen and hydroxyl radicals near PSII. We also hind that under the heat stress, not only the D1 protein but also D2, PsbO and PsbQ proteins are oxidatively damaged. PsbO and other extrinsic proteins were released from PSII under the heat stress. As heat stress induced significant lipid peroxidation near PSII, we speculate that the heat-induced lipid peroxidation is related to the damage to PSII.(3) In the mutant of Synechocystis PCC6803 lacking FtsH (slr0228), excess light induced significant aggregation of the D1 protein, compared with the wild-type cells. These results indicate that the FtsH protease degrades the D1 aggregates, or alternatively that the FtsH protease acts as a molecular chaperone to avoid protein aggregation. We are continuing the study using other protease mutants as well.

光系统II（PSII）是各种非生物胁迫的目标，包括过量的可见光和高温。PSII的反应中心D1蛋白在这些胁迫下容易被破坏，并且被破坏的蛋白质被特异性蛋白酶降解或与附近的多肽如D2蛋白或CP 43形成聚集体。在本研究中，我们分析了光或热损伤的D1蛋白的降解和聚集途径的细节，使用菠菜类囊体和蓝藻集胞藻PCC 6803。主要研究结果如下：（1）菠菜类囊体在40℃热胁迫30 min时，D1蛋白被破坏，FtsH蛋白酶降解了D1蛋白。我们通过FtsH的溶解和重构实验证明了FtsH蛋白酶的作用。(2)我们发现，热胁迫诱导活性氧物种，如单线态氧和羟基自由基附近的PSII。在热胁迫条件下，不仅D1蛋白受到氧化损伤，D2、PsbO和PsbQ蛋白也受到氧化损伤。热胁迫下PSII释放PsbO等外源蛋白。由于热胁迫诱导了PSII附近的脂质过氧化反应，推测热诱导的脂质过氧化反应与PSII的损伤有关。(3)在缺乏FtsH的集胞藻突变体PCC6803（slr0228）中，与野生型细胞相比，过量的光诱导D1蛋白的显著聚集。这些结果表明，FtsH蛋白酶降解D1聚集体，或者FtsH蛋白酶作为分子伴侣，以避免蛋白质聚集。我们也在继续使用其他蛋白酶突变体进行研究。