Localization and Functions of Novel Proteins in Cyanobacterial Photosystem II

光系统II是蓝藻和叶绿体中的一种膜蛋白复合体，它在生物圈中介导了一种独特的反应，即将水氧化为分子氧。虽然光合作用放氧的确切分子机制仍不清楚，但已知锰、钙和氯离子簇对这一活动是必不可少的。该项目的长期目标是确定光系统II的各种蛋白质成分在水氧化机制中的作用。对聚球藻6803的高效PSII蛋白进行了蛋白质组学分析，发现了4种新的蛋白质S111390、S111252、S111414、S111130以及PSBP和PsbQ蛋白，这些蛋白以前被认为只存在于高等植物和绿藻的叶绿体中。该项目包括详细的生化和遗传学研究，以确定蓝藻和植物光系统II中上述蛋白质的细胞定位和功能。通过收集太阳辐射，光系统II复合体贡献了地球上一半的生物量。在过去的一年里，以3.8A的分辨率描述了蓝藻光系统II复合体的X射线晶体结构。然而，更详细地了解光系统II的蛋白质组分的组织和功能对于全面理解光合作用的O2-释放机制是必要的。拟议的实验有望补充预期的更高分辨率的光系统II的X射线晶体分析，以获得这样的理解水平。这些实验还将为光系统II从蓝藻到高等植物的形式和功能的进化提供新的线索。此外，该项目将为一些本科生、研究生和博士后实习生提供最先进的研究机会。

Photosystem II, a membrane protein complex in cyanobacteria and chloroplasts, mediates a unique reaction in the biosphere, oxidation of water to molecular oxygen. Although the exact molecular mechanism of photosynthetic oxygen evolution remains elusive, it is known that a cluster of manganese, calcium and chloride ions is essential for this activity. The long-term goal of this project is to define the roles of various protein components of photosystem II in the mechanism of water oxidation. Proteomic analysis of a highly active PSII preparation from the cyanobacterium Synechocystis 6803 has identified four novel proteins, Sll1390, Sll1252, Sll1414, Sll1130, as well as the PsbP and PsbQ proteins, which were previously thought to be present only in higher plant and green algal chloroplasts. This project includes detailed biochemical and genetic studies to determine the cellular localization, and functions of the above proteins in cyanobacterial and plant photosystem II.By harvesting solar radiation, the photosystem II complex contributes to half of the biomass production on our planet. During the past year, X-ray crystal structure of a cyanobacterial photosystem II complex has been described at a 3.8A resolution. However, a more detailed understanding of the organization and functions of the protein components of photosystem II are necessary to fully comprehend the mechanism of photosynthetic O2-evolution. The proposed experiments are expected to complement anticipated higher resolution X-ray crystallographic analysis of photosystem II to gain such a level of understanding. These experiments will also shed new light on the evolution of the form and function of photosystem II from cyanobacteria to higher plants. In addition, this project will provide state-of-the-art research opportunities to a number of undergraduate, graduate and postdoctoral trainees.