Structural Studies of Photosynthetic Membrane Proteins

紫色光合细菌中的光捕获天线系统的效率大于90%，是显著的。充分理解这种效率的先决条件是对天线系统的主要组成部分LH 1，LH 2和反应中心（RC）的详细结构知识，这些都是膜蛋白。LH 1的结构仅在4.8A的分辨率下已知，并且比LH 2和RC单独表征得更少。该提案概述了计划，以获得中等至高分辨率的LH 1系统和相关的LH 1-RC复合物的结构细节，通过利用固态核磁共振（SS NMR）的条件下的魔角旋转（MAS）结合二维和三维NMR实验和选择性同位素标记的蛋白质样品。该方法采用SS NMR获得序列特异性分配的LH 1系统的所有成分的氨基酸残基，使用这些分配和额外的NMR实验，以确定结构的限制。拟议的研究将提供有关光合作用的信息，并进一步测试SS NMR方法对膜蛋白的研究-这是生物化学研究的一个关键领域，在医学领域具有重要应用。

DESCRIPTION (provided by applicant) The efficiency of the light harvesting antenna system in purple photosynthetic bacteria, at greater than 90%, is remarkable. A prerequisite to full understanding of this efficiency is a detailed structural knowledge of the major components of the antenna system, LH1, LH2, and the Reaction Center (RC), which are all membrane proteins. The structure of LH1 is only known to a resolution of 4.8A, and is less-well characterized than LH2 and the RC alone. This proposal outlines plans to obtain moderate to high-resolution structural detail of the LH1 system and the related LH1-RC complex, by utilizing Solid State Nuclear Magnetic Resonance (SS NMR) under conditions of Magic Angle Spinning (MAS) in conjunction with two- and three-dimensional NMR experiments and selective isotopic labeling of protein samples. The methodology employs SS NMR to obtain sequence-specific assignments of the amino acid residues of all constituents of the LH1 system, using these assignments and additional NMR experiments to determine structural constraints. The proposed study will provide information about photosynthesis and a further test of SS NMR methods to the study of membrane proteins - a crucial area of biochemical research with significant applications in the medical field.