Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
Science. 2022 Aug 19;377(6608):865-869. doi: 10.1126/science.abq7641. Epub 2022 Jul 28.
The enzyme nitrogenase couples adenosine triphosphate (ATP) hydrolysis to the multielectron reduction of atmospheric dinitrogen into ammonia. Despite extensive research, the mechanistic details of ATP-dependent energy transduction and dinitrogen reduction by nitrogenase are not well understood, requiring new strategies to monitor its structural dynamics during catalytic action. Here, we report cryo-electron microscopy structures of the nitrogenase complex prepared under enzymatic turnover conditions. We observe that asymmetry governs all aspects of the nitrogenase mechanism, including ATP hydrolysis, protein-protein interactions, and catalysis. Conformational changes near the catalytic iron-molybdenum cofactor are correlated with the nucleotide-hydrolysis state of the enzyme.
酶氮还原酶将三磷酸腺苷（ATP）水解与大气氮气的多电子还原反应偶联为氨。尽管进行了广泛的研究，但氮还原酶的 ATP 依赖能量转导和氮气还原的机制细节仍不清楚，需要新的策略来监测其在催化作用过程中的结构动力学。在这里，我们报告了在酶转化条件下制备的氮还原酶复合物的低温电子显微镜结构。我们观察到，不对称性控制着氮还原酶机制的各个方面，包括 ATP 水解、蛋白质-蛋白质相互作用和催化。靠近催化铁-钼辅因子的构象变化与酶的核苷酸水解状态相关。
