Primary Processes in Photosystem I

光合作用的有机体使用双重策略来捕获和存储太阳能。天线系统首先收集光线，然后将能量转移到电子转移系统，电子转移系统将电子激发转化为可用于细胞生长的氧化还原能量。在大多数光合作用系统中，天线和电子传递函数位于可分离的复合体上，可以独立研究。然而，在氧气光合作用有机体的光系统I中，天线和电子传递功能被融合成一个具有这两种功能的单一大型复合体。为了提高我们目前对这类重要的光合作用反应中心中的能量捕获过程、初级光化学和早期次级电子转移反应的认识，提出了一些实验。这项工作的总体目标是了解天线系统与电子转移系统的耦合以及早期电子转移过程的途径。本项目的具体实验包括：1)对苯二酚和色素结合区的光系统I突变体的研究；2)利用蛋白质工程将光系统I反应中心复合体分离到天线和电子转移区域；3)分析新发现的含有叶绿素d的生物体--无叶绿藻中的光系统I能量捕获和电子转移。这个项目将增加我们对植物和其他光合作用生物如何将太阳光能量转化为化学能的理解。光合作用过程提供了我们所有的食物和大部分的能量需求。这个项目的目的是让人们详细了解这一重要生物过程的化学机制。

Photosynthetic organisms use a twofold strategy to capture and store solar energy. An antenna system first collects light and then transfers the energy to an electron transfer system that converts electronic excitation into redox energy that can be used for cell growth. In most photosynthetic systems, the antenna and electron transfer functions are located on separable complexes and can be studied independently. However, in Photosystem I of oxygenic photosynthetic organisms, the antenna and electron transfer functions are fused into a single large complex that serves both functions. Experiments are proposed to improve our current fragmentary understanding of the energy trapping processes, primary photochemistry and early secondary electron transfer reactions in this important class of photosynthetic reaction centers. Overall goals of the work are to understand the coupling of the antenna system to the electron transfer system and the pathway of the early electron transfer processes. Specific experiments in this project include: 1) Studies on Photosystem I mutants in the quinone and pigment binding regions, 2) Separation of the Photosystem I reaction center complex into antenna and electron transfer domains using protein engineering and 3) Analysis of Photosystem I energy trapping and electron transfer in a newly-discovered chlorophyll d-containing organism, Acaryochloris marina. This project will increase our understanding of how plants and other photosynthetic organisms convert the energy of sunlight into chemical energy. The process of photosynthesis supplies all of our food and most of our energy needs. This project is designed to give detailed knowledge of the chemical mechanism of this essential biological process.