Disassembly and degradation of Photosystem I

描述(申请人提供)：本项目的长期目标是 了解膜蛋白复合体是如何分解和降解的。许多 蛋白质以一种有规律的、耗能的方式降解，蛋白质 被细胞识别为异常的是这些“质量控制”的目标 系统优先。尽管用来降解的细胞机制 可溶蛋白质正在变得很好地理解，相应的知识 膜蛋白的研究进展滞后，尽管许多膜起着关键作用。 蛋白质在重要的过程中发挥作用，例如信号转导， 生物能量学和细胞动态平衡。人类的几种疾病，如囊肿症 纤维化和视网膜色素变性是由膜的降解引起的。 具有点突变的蛋白质。这里提出的模型系统是 单细胞绿藻-莱茵衣藻的光系统I复合体。 这种蛋白质是光合作用电子传递的重要组成部分。 链，并利用其相关的叶绿素分子吸收的光来驱动 电子在类囊体膜上的传递。它应该作为一种 膜蛋白降解的极佳模型底物，因为 蛋白质的功能部分在膜的平面上，在那里它有 它内置了许多光谱探测器。该项目包括 抑制基因和生物化学的互补方法。具体的 该项目的目标是1)分离出减缓一种基因退化的突变 突变的光系统I蛋白，通常是质量控制的靶标 系统；2)表征突变体表型的特异性；3) 创建一个忠实地模仿体内的体外降解系统 过程；以及4)使用该系统来表征过程和识别 其中涉及的一些因素。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how membrane protein complexes are disassembled and degraded. Many proteins are degraded in a regulated and energy-consuming fashion, and proteins recognized by the cell as aberrant are targeted by these "quality control" systems preferentially. Although the cellular mechanisms used to degrade soluble proteins are becoming well understood, knowledge of the corresponding process for membrane proteins has lagged, despite the key role many membrane proteins play in important processes, such as signal transduction, bioenergetics, and cellular homeostasis. Several human diseases, such as cystic fibrosis and retinitis pigmentosa, are caused by degradation of membrane proteins with point mutations. The model system proposed here is the photosystem I complex in the unicellular green alga, Chlamydomonas reinhardtii. This protein is an essential part of the photosynthetic electron transport chain and uses light absorbed by its associated chlorophyll molecules to drive electron transfer across the thylakoid membrane. It should serve as an excellent model substrate for membrane protein degradation, because the functional portion of the protein is in the plane of the membrane, where it has many spectroscopic probes built into it. The project comprises the complementary approaches of suppressor genetics and biochemistry. The specific aims of the project are 1) to isolate mutations that slow the degradation of a mutant photosystem I protein that is normally targeted by the quality control system; 2) to characterize the specificity of the mutants' phenotypes; 3) to create an in vitro degradation system that faithfully mimics the in vivo process; and 4) to use this system to characterize the process and identify some of the factors involved in it.