Pathways of electron and proton flow in a transmembrane, photon-driven quinone reductase/translocase supercomplex of proteins

这项拟议的研究旨在细胞过程组分之间的相互作用，在胞质膜片段和由膜结合催化剂的单个蛋白质组分组成的原子之间的尺度上。我们正在研究跨膜蛋白复合物内部和之间相互作用域的结构和功能，重点是我们称之为RC/LH1/PufX超复合物。该光合色素-蛋白超复合物由反应中心（RC）复合物、光收集1 （LH1）复合物和PufX蛋白关键组分组成。主要目的是阐明RC/LH1/PufX超复合物中电子和质子的流动途径，该复合物在模式生物球形红杆菌中作为光子（光）驱动的醌还原酶/转位酶发挥作用。其他目标是确定超复合体如何组装和转运醌，以及rc特异性辅助因子细菌叶绿素的生物发生。我们还希望解决RC/LH1/PufX超复合体的高分辨率晶体结构，以提供对PufX蛋白的位置和功能的三维见解，并促进位点定向诱变实验的设计和解释，以测试由结构数据产生的功能假设。这项研究对于推进蛋白质催化电化学反应的基础知识，特别是在利用生物材料发电的应用方面具有重要意义。因此，这项研究不仅引起了科学家的兴趣，而且也引起了公众的兴趣，因为他们可以从太阳能的应用中受益。预计该研究将促进对膜蛋白超复合体组装和相互作用的理解，并为基于生物系统的光伏器件工程提供额外的潜力。改进的光电设备将使加拿大受益，因为它允许更多地使用一种清洁的、基本上是无限的能源。

This proposed research is aimed at interactions between components of cellular processes, on a scale intermediate between cytoplasmic membrane fragments and the atoms comprising individual protein components of membrane-bound catalysts. We are studying the structure and function of domains of interaction within and between transmembrane protein complexes, with a focus on what we call the RC/LH1/PufX supercomplex. This photosynthetic pigment-protein supercomplex is composed of the reaction center (RC) complex, the light-harvesting 1 (LH1) complex, and the PufX protein key component. The primary goal is to elucidate pathways of electron and proton flow in the RC/LH1/PufX supercomplex, which functions as a photon- (light-) driven quinone reductase/translocase in a model organism, the bacterium Rhodobacter sphaeroides. Other goals are to determine how the supercomplex assembles and translocates quinones, and the biogenesis of the RC-specific cofactor, bacteriopheophytin. We also wish to solve a high-resolution crystal structure of an RC/LH1/PufX supercomplex to provide 3-D insights into the location and function of the PufX protein, and to facilitate the design and interpretation of site-directed mutagenesis experiments to test functional hypotheses arising from the structural data. This research is important to advance fundamental knowledge of the catalysis of protein-catalyzed electrochemical reactions, especially in relation to applications using biological material to generate electricity. Thus this research is of interest not only to scientists, but also the general public who could benefit from applications to harvest solar energy. It is anticipated that this research will advance the understanding of the assembly and interaction of membrane protein supercomplexes in general, with the additional potential of providing a foundation for the engineering of photovoltaic devices based on biological systems. Improved photovoltaic devices would benefit Canada by allowing increased use of a clean, essentially limitless energy source.