The Role of the D2 Protein in the Photosystem II Complex as Probed by Directed Mutagenesis and Mutant Analysis

D2蛋白是光系统II的核心成分 复杂的光合作用膜，但其确切的功能是 未知 特定氨基酸残基的作用， D2多肽区的功能、结构和组装 光系统II复合体正在由 诱变技术。 特异性突变被诱导D2。 的 携带定点突变的psbD-I基因（编码D2）是 引入到可转化光合异养菌的突变体中， 蓝细菌集胞藻6803，其中两个psbD基因 拷贝（psbD-I和psbD-II）已删除。 目标区域 创建D2突变部分通过与 与紫色反应中心部分同源的M亚基 细菌，其详细结构已知。 的 突变型光系统II复合物的性质在一个 各种方法，包括mRNA的研究，和分析， 光系统II蛋白质组成和合成，电子 运输，叶绿素荧光，特定的EPR信号， 除草剂结合和闪光诱导的吸光度变化。 这个项目的结果将导致详细的了解 特定的残基和区域在一个重要的， 对光合膜中的蛋白质知之甚少。 洞察力 将获得氧化复合物是如何组织的。 潜在的重要性在于蛋白质复合物可以是 * *

The D2 protein is a central component of the Photosystem II complex in photosynthetic membranes, but its precise function is unknown. The role of specific amino acid residues and polypeptide regions of D2 in function, structure and assembly of the Photosystem II complex is being studied by directed mutagenesis techniques. Specific mutations are induced D2. The psbD-I gene (encoding D2) carrying site-directed mutations is introduced into a mutant of the transformable photoheterotrophic cyanobacterium Synechocystis 6803, from which the two psbD gene copies (psbD-I and psbD-II) have been deleted. Target regions to create D2 mutations are identified in part by comparison with the partially homologous M subunit of the reaction center from purple bacteria, for which the detailed structure is known. The properties of the mutant Photosystem II complex are analyzed in a variety of ways, including mRNA studies, and analysis of Photosystem II protein composition and synthesis, electron transport, chlorophyll fluorescence, specific EPR signals, herbicide binding, and flash-induced absorbance changes. The results of this project will lead to a detailed understanding of the role of specific residues and regions in an important but poorly understood protein in photosynthetic membranes. Insight will be gained on how the oxidizing complex is organized. Potentially significant is that the protein complex can be altered to result in more efficient operation.***//