The chloroplast 22-Ku heat-shock protein: A lumenal protein that associates with the oxygen evolving complex and protects photosystem II during heat stress
The chloroplast 22-Ku heat-shock protein: A lumenal protein that associates with the oxygen evolving complex and protects photosystem II during heat stress
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DOI：
10.1016/s0176-1617(99)80042-x
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发表时间：
1999-10-01
影响因子：
4.3
通讯作者：
Heckathorn, SA
中科院分区：
文献类型：
--
作者：
Downs, CA;Coleman, JS;Heckathorn, SA
一个进化上保守的小的热休克蛋白定位于叶绿体（chlpsHsp）在所有主要门的陆生植物研究的日期。已知chlpsHsp在热胁迫期间保护光合电子传递，特别是光系统II的电子传递。亚细胞器检查表明，有两种形式的chlpsHsp，25-Ku和22-Ku形式。分离的亚叶绿体组分（类囊体基粒与基质）的蛋白酶处理表明，22-Ku chlpsHsp形式被发现在类囊体腔。使用低于其临界胶束浓度的Triton X-100的浓度的chlpsHsp的免疫共沉淀表明，该蛋白质与光系统II的蛋白质相关联。使用浓度的Triton X-100显着高于其临界胶束浓度的chlpsHsp的免疫共沉淀表明，这种蛋白质特异性地与光系统II的热不稳定的放氧复合物的蛋白质相互作用。chlpsHsp不能重新激活热变性的光系统II，但在热应激期间保护该复合物免受损害。
An evolutionarily conserved small heat-shock protein localizes to the chloroplast (chlpsHsp) in all major phyla of terrestrial plants examined to date. The chlpsHsp is known to protect photosynthetic electron transport, specifically that of Photosystem II, during heat stress. Suborganellar examination indicated that there are two forms of the chlpsHsp, a 25-Ku and a 22-Ku form. Protease treatment of isolated subchloroplast fractions (thylakoid grana vs, stroma) demonstrated that the 22-Ku chlpsHsp form is found in the thylakoid lumen. Co-immunoprecipitation of the chlpsHsp using a concentration of Triton X-100 below its critical micelle concentration showed that this protein associates with proteins of Photosystem II. Coimmunoprecipitation of the chlpsHsp using a concentration of Triton X-100 significantly above its critical micelle concentration showed that this protein specifically interacts with proteins of the thermolabile Oxygen Evolving Complex of Photosystem II. The chlpsHsp does not reactivate heat-denatured Photosystem II, bur instead protects this complex from damage during heat stress.