Mutational Analysis of Photosystem I Function

9723001 Chitnis 1。光系统I，光驱动的质体青素-铁氧化还蛋白氧化还原酶，是蓝藻和叶绿体光合膜中的一种异聚色素-蛋白质复合物。基于x射线晶体学、光谱学和基因组学信息，研究者提出表征光系统I蛋白在蛋白间电子转移和醌辅助因子结合过程中的分子识别。在光系统I的还原侧，PsaD对铁氧还蛋白的对接至关重要。利用分子遗传学和蛋白质化学，研究者已经确定了暴露在铁氧化还原蛋白相互作用的PsaD表面的基本残基。他将使用定点诱变和生化研究来检查这些基本残基在与铁氧还蛋白相互作用中的作用。光系统I包含两个叶绿醌分子，其中一个作为氧化还原中心A1，将电子从A0叶绿素a转移到FX铁硫簇。基于现有的结构和光谱信息，研究者提出PsaA和PsaB蛋白最后基质环上保守的YW序列是叶绿醌结合位点的重要组成部分。这些残基将产生突变以识别A1结合亚基。研究者将利用分子遗传学操纵叶绿醌生物合成途径。他将删除编码萘酚酸合成酶的menB基因。由此产生的突变体将用于在体内检测叶绿醌2。电子转移反应是光合作用、呼吸作用和许多其他生化途径的关键步骤。细胞中的能量产生依赖于电子跨膜传递。研究者将研究光合电子转移过程中蛋白质相互作用和功能的分子基础。本研究将试图揭示生物系统有效捕获光能及其储存的机制。植物、藻类和蓝藻中的产氧光合作用是地球上生物能和氧气的主要来源。研究者的工作将增加光合作用的知识，并将提供可能用于作物植物光合作用基因操作的信息

9723001 Chitnis 1. Technical Photosystem I, the light-driven plastocyanin-ferredoxin oxidoreductase, is a heteromultimeric pigment-protein complex in the photosynthetic membranes of cyanobacteria and chloroplasts. Based on X-ray crystallographic, spectroscopic and genomic information, the investigator proposes to characterize molecular recognition during interprotein electron transfer and binding of quinone cofactors by photosystem I proteins. On the reducing side of photosystem I, PsaD is essential for docking of ferredoxin. Using molecular genetics and protein chemistry, the investigator has identified basic residues that are exposed on the ferredoxin-interacting surface of PsaD. He will use site-directed mutagenesis and biochemical studies to examine the role of these basic residues in interaction with ferredoxin. Photosystem I contains two phylloquinone molecules, one of which serves as the redox center A1 which transfers electrons from the A0 chlorophyll a to the FX iron-sulfur cluster. Based on the available structural and spectroscopic information, the investigator proposes that the conserved YW sequences in the last stromal loop of the PsaA and PsaB proteins are essential components of the phylloquinone-binding sites. Mutations in these residues will be generated to identify the A1 binding subunit. The investigator will manipulate the phylloquinone biosynthetic pathway using molecular genetics. He will delete the menB gene that encodes naphtholate synthase. The resulting mutants will be used to examine phylloquinone in vivo 2. Non Technical Electron transfer reactions are crucial steps in photosynthesis, respiration, and many other biochemical pathways. Energy generation in a cell is dependent on electron transfer across membranes. The investigator will study the molecular basis of protein interactions and function during photosynthetic electron transfer. This research will attempt to unravel the mechanisms of efficient capture of light energy and its storage by living systems. Ox ygenic photosynthesis in plants, algae and cyanobacteria is the major source of biological energy and oxygen on the earth. The investigator's work will increase the knowledge of photosynthesis and will provide information that can potentially be used for genetic manipulation photosynthesis in crop plants