Collaborative Research: Site-Directed Mutagenesis of the Manganese Stablizing Protein of Photosynthesis

导致光合作用水氧化的分子事件在很大程度上仍然未知，特别是所涉及的蛋白质和形成锰配体的特定残基，锰是氧气进化的重要辅助因子。目前的模型表明，参与反应中心D1D2复合物和外源性33kD蛋白，称为锰稳定蛋白。这项研究将结合定点诱变技术，利用易于转化的蓝细菌Synechocystis 6803来修饰选定的氨基酸残基，这些氨基酸残基包括所谓的锰稳定多肽。结合EPR和ENDOR光谱方法，可以直接评估锰位点和其他与反应中心耦合的内源性电子给体（如Cytb559和Tyr- 160）的结构和动力学性质的变化。光合作用是地球表面最普遍的生物反应。它产生了空气中几乎所有的氧气，而氧气对所有需氧生物的氧化代谢和化石燃料发动机的燃烧都是必不可少的。因此，光合作用的氧气进化为大多数生物和商业机器提供动力。目前还没有一种人造催化剂能够有效地从水和一种具有商业用途产量的能源中分解氧气。另一方面，大自然已经开发出一种独特的系统，在所有的臭氧进化植物和藻类中都有发现，它对催化这一过程进行了优化。这项研究将有助于理解分子基础，通过分子基础，绿色植物能够利用自然界最强大的氧化剂，分裂的生物过程，我们希望获得洞察力，这将导致一个新的蓝图，设计合成水氧化催化剂

The molecular events leading to photosynthetic water oxidation are still largely unknown, particularly the proteins involved and the specific residues that form ligands to manganese, an essential cofactor for oxygen evolution. Current models suggest the participation of the reaction center D1D2 complex and an extrinsic 33kD protein, called the maganese stabilizing protein. This research will combine the techniques of site-directed mutagenesis, using the readily transformable cyanobacterium Synechocystis 6803, to modify selected amino acid residues comprising the so-called manganese stabilizing polypeptide, together with EPR and ENDOR spectroscopic methods which enable a direct assessment of these changes on the structure and kinetic properties of the manganese site and other endogenous electron donors coupled to the reaction center, such as Cytb559 and Tyr- 160.%%% Photosynthesis is the most pervasive biological reaction on the face of the earth. It produces nearly all of the oxygen in the air which is essential for oxidative metabolism in all aerobic organisms and for combustion in fossil fuel powered engines. Thus, photosynthetic O2 evolution powers most biological and commercial machines. Presently there are no man-made catalysts capable of carrying out the efficient evolution of O2 from water and an energy source with a commercially useful yield. Nature, on the other hand, has developed a unique system, found in all O2-evolving plants and algae, optimized for catalyzing this process. This research will contribute to the understanding of the molecular basis by the molecular basis by which green plants are capable of harnessing nature's most power oxidant, the splitting of the biological process we hope to gain insight that will lead to a new blueprint for the design of synthetic water oxidizing catalysts.***//