AKR2A参与分选及定位叶绿体外被膜蛋白的结构基础

项目名称： AKR2A参与分选及定位叶绿体外被膜蛋白的结构基础

项目编号： No.31300634

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 生物科学

项目作者： 李红美

作者单位： 中国科学院植物研究所

项目金额： 22万元

中文摘要： 叶绿体是负责光合作用的细胞器。虽然叶绿体中含有自己的基因组，但其大多数蛋白质是由核基因组编码的。核基因编码的蛋白经翻译后修饰从细胞质转运到叶绿体。核编码蛋白正确定位到叶绿体各腔室之前，需要在细胞质内被正确分选并定位到叶绿体外被膜上。但到目前为止该方面的研究很少。最近研究发现AKR2A在参与分选及定位叶绿体外被膜蛋白方面起着重要的作用。AKR2A作为可溶性胞内分选因子，结合一类含有TMD及CPR锚定信号的外被膜蛋白OEP7及Toc33；此外，AKR2A具有分子伴侣作用，阻止外被膜蛋白聚集沉淀，增加其可溶性并促进其定位。本课题的目标是通过解析AKR2A及其与OEP7（Toc33）复合物的晶体结构，深入研究AKR2A参与分选及结合叶绿体外被膜蛋白的分子机制，这对于理解叶绿体蛋白的生物发生、光合细胞器的建成和功能的实现以及真核生物的起源和进化等都有十分重要的意义。

中文关键词： 晶体结构；蛋白表达；纯化；复合物；降解

英文摘要： Chloroplasts are unique organelles that are responsible for photosynthesis. Although chloroplasts contain their own genome, the majority of chloroplast proteins are encoded by the nuclear genome. These proteins are transported to the chloroplasts after translation in the cytosol. Prior to targeting these proteins to the various compartments of the chloroplast, they must be correctly sorted in the cytosol and targeted to the chloroplast outer envelope membrane (OEM) .To date, it is not clear how these proteins are sorted and targeted to the chloroplasts. Recently, the cytosolic carrier protein AKR2A was identified, which plays important roles in sorting an targeting chloroplast OEM proteins. AKR2A, as a soluble cytosolic factor, can bind chloroplast OEM protein OEP7 and Toc33 containing TMD and CPR anchored signal. In addition, AKR2A facilitates the targeting of OEM protein to chloroplast, which exhibits chaperone activity and prevents chloroplast OEM protein aggregation. Structural analysis of AKR2A and complex between AKR2A and OEM proteins can help to study the specific sites and the way of AKR2A binding OEM proteins and reveal the molecular mechanism of outer chloroplast protein sorting and targeting, which is essential for understanding the chloroplast biogenesis, photosynthetic apparatus building and funct

英文关键词： Crystal structure；protein expression；purification；complex；degradation