Mutational Analysis of Photosystem I Function

9723001几丁糖1.光系统I是蓝藻和叶绿体光合膜中的一种异型多聚体色素-蛋白质复合体，是光驱动的叶绿体色素蛋白氧化还原酶。基于X射线结晶学、光谱学和基因组学信息，研究人员提出了光系统I蛋白在蛋白质间电子转移和苯醌辅助因子结合过程中的分子识别特征。在光系统I的还原侧，PSAD对于铁氧还蛋白的对接是必不可少的。利用分子遗传学和蛋白质化学，研究人员已经确定了暴露在PSAD铁氧还蛋白相互作用表面的碱性残基。他将使用定点突变和生化研究来检查这些碱性残基在与铁氧还蛋白相互作用中的作用。光系统I含有两个叶醌分子，其中一个分子作为氧化还原中心A1，将电子从A0的叶绿素a转移到Fx的铁硫团簇。根据现有的结构和光谱信息，研究人员提出，在psaA和psaB蛋白的最后一个基质环中保守的yw序列是叶醌结合位点的重要组成部分。这些残基中的突变将被产生以识别A1结合亚基。研究人员将利用分子遗传学来操纵叶醌的生物合成途径。他将删除编码环状合成酶的MenB基因。由此产生的突变体将用于在体内检测叶醌2。非技术性电子转移反应是光合作用、呼吸作用和许多其他生化途径中的关键步骤。细胞中的能量产生依赖于跨膜的电子转移。研究人员将研究蛋白质在光合作用电子转移过程中相互作用和功能的分子基础。这项研究将试图揭开生物系统有效捕获光能和储存光能的机制。植物、藻类和蓝藻的氧合作用是地球上生物能量和氧气的主要来源。研究人员的工作将增加关于光合作用的知识，并将提供可能用于作物光合作用的遗传操作的信息

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