Structural Studies of Alternating-site Reactivity in Nitrogenase-like Oxidoreductases

项目总结/摘要 大自然利用蛋白质变构来控制化学反应中的远程电子流 终身金属和金属簇通常是促进这种电子转移的关键组分。一 已知用于在金属酶中门控电子流的变构方法是交替位点反应性， 其中当构象改变时，反应性从酶的一半切换到另一半， 变化氧化还原酶是一种以α2β2为核心的铁硫簇合物 金属酶，采用交替位点反应，可以作为一个宝贵的模型 定义金属酶变构所需的结构基序和机制的系统 调控根据NIH NIGMS药理学、生理学和生化学 使命是“提高对基本生物过程的分子水平理解， 发现控制它们的方法”，我们建议研究两种这样的氧化还原酶， 固氮酶样暗操作叶绿素氧化还原酶（DPOR）和叶绿素 氧化还原酶（COR），以确定长期相关的运动如何有助于交替- 使用结构生物学工具的位点反应性。我们将使用电子显微镜和小角度 X射线散射技术检测具有不对称构象的酶构象中间体 构象

Project Summary / Abstract Nature uses protein allostery to control long-range electron flow in chemical reactions essential for life. Metals and metal-clusters are often key components facilitating this electron transfer. A known allosteric method for gating electron flow in metalloenzymes is alternating-site reactivity, wherein reactivity switches from one half of the enzyme to the other upon conformational changes. Oxidoreductases, with a core α2β2 heterotetrameric structure, are iron-sulfur cluster metalloenzymes that employ alternating-site reactivity and can serve as an invaluable model system to define the structural motifs and mechanisms required for metalloenzyme allosteric regulation. In line with the NIH NIGMS Pharmacology, Physiology, and Biochemical Chemistry mission of “improving molecular level understanding of fundamental biological processes and discovering approaches to their control”, we propose to study two such oxidoreductases, the nitrogenase-like dark-operative chlorophyllide oxidoreductase (DPOR) and chlorophyllide oxidoreductase (COR), to identify how long-ranged correlated motions contribute to alternating- site reactivity using structural biology tools. We will employ electron microscopy and small-angle X-ray scattering techniques to examine enzyme conformational intermediates with asymmetrical conformations.