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研究细胞过程组件之间的相互作用，在细胞质膜碎片和组成膜结合催化剂的单个蛋白质组件的原子之间的尺度上。我们正在研究跨膜蛋白复合体内部和之间相互作用区域的结构和功能，重点是我们所称的RC/LH1/PufX超复合体。这个光合色素-蛋白质超复合体由反应中心(RC)复合体、捕光1(LH1)复合体和PufX蛋白关键成分组成。主要目标是阐明RC/LH1/PufX超复合体中的电子和质子流动路径，该超复合体在模式生物球形红杆菌中作为光子(光)驱动的苯醌还原/转位酶发挥作用。其他目标是确定超复合体如何组装和移位苯醌，以及RC特异性辅因子细菌菲藻素的生物发生。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蛋白位置和功能的三维见解，并促进定点突变实验的设计和解释，以测试由结构数据产生的功能假说。这项研究对推进蛋白质催化电化学反应的基础知识很重要，特别是在利用生物材料发电的应用方面。因此，这项研究不仅对科学家感兴趣，而且对可能从太阳能采集应用中受益的普通公众也是如此。预计这项研究将从总体上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的工程提供基础。改进的光伏设备将使加拿大受益，因为它允许更多地使用清洁的、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.