The Role of Supernumeral Subunit of Bacterial Cytochrome b-c1 Complex

9630413 Yu本研究的目的是阐明亚基IV（Mr = 14，384）在光合细菌Rhodobacter sphaeroides的细胞色素bc1复合物中的作用。 通过定点突变、突变体亚基IV与三亚基核心复合物的体外重组以及重组复合物的物理、化学表征，将鉴定（1）亚基IV与三亚基核心复合物相互作用所必需的色氨酸残基;（2）亚基IV中与细胞色素B和铁硫蛋白相互作用的结构域;和（3）稳定细胞色素Bc1复合物结构所需的氨基酸残基。 该项目的成功将增加我们对这种光合细菌bc1复合体的结构-功能和机制以及细胞色素bc1复合体中能量传递的理解。 更好地理解光合机构中的能量转换机制将导致提高光合作用的效率，从而增加可再生能源。 光合作用是将光能转化为用于生物合成的化学能的过程。 一些细菌和植物都有这种能力。 细菌光合途径的一个组成部分是细胞色素bc1复合物。 亚基IV是该复合物的一个组分，在氧化还原反应中没有明显的作用。 本项目的目标是阐明三亚基核心复合物中该亚基的相互作用和作用。 提出的实验将提高我们的理解，在光合机构的能量转换机制，提高这一过程的效率的长期目标。 ***

9630413 Yu The objective of this research is to elucidate the role of subunit IV (Mr=14,384) in the cytochrome bc1 complex from a photosynthetic bacterium Rhodobacter sphaeroides. Site-directed mutagenesis, in vitro reconstitution of mutant subunit IV with the three-subunit core complex, and physical, chemical characterizations of reconstituted complex will be employed to identify (1) the tryptophan residue(s) of subunit IV essential for interaction with the three-subunit core complex; (2) the domains in subunit IV interacting with cytochrome b and with iron-sulfur protein; and (3) the amino acid residues required for stabilizing the structure of the cytochrome bc1 complex. The success of this project will increase our understanding of the structure-function and mechanism of this photosynthetic bacterial bc1 complex in particular and energy transduction in the cytochrome bc1 complex in general. A better understanding of energy transduction mechanisms in the photosynthetic apparatus will lead to increase the efficiency of photosynthesis and thus increases the renewable energy sources. %%% Photosynthesis is the process of conversion of light energy into chemical energy for use in biosynthesis. Some bacteria as well as plants have this ability. One component of the bacterial photosynthetic pathway is the cytochrome bc1 complex. Subunit IV is one component of this complex which has no obvious role in oxidation-reduction reactions. The goal of this project is to elucidate the interactions and role of this subunit within the three-subunit core complex. The experiments proposed will enhance our understanding of energy transduction mechanisms in the photosynthetic apparatus with a long-range goal of increasing the efficiency of this process. ***