Hu Yilin, Ribbe Markus W
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, 92697-3900, USA.
Department of Chemistry, University of California, Irvine, CA, 92697-2025, USA.
J Biol Inorg Chem. 2025 Mar;30(2):135-149. doi: 10.1007/s00775-024-02086-6. Epub 2024 Dec 12.
The Mo-nitrogenase catalyzes the reduction of N to NH at the cofactor of its catalytic NifDK component. NifEN shares considerable homology with NifDK in primary sequence, tertiary structure and associated metallocenters. Better known for its biosynthetic function to convert an all-iron precursor (L-cluster; [FeSC]) to a mature cofactor (M-cluster; [(R-homocitrate) MoFeSC]), NifEN also mimics NifDK in catalyzing substrate reduction at ambient conditions. The recently discovered ability of NifEN to reduce N to NH is particularly interesting, as it points to NifEN as a plausible, prototype ancient nitrogenase during evolution. Moreover, the dual function of NifEN in assembly and catalysis makes it a great template to reconstruct the functional variants or equivalents of NifDK, which could facilitate the mechanistic investigation and heterologous synthesis of nitrogenase. This perspective provides an overview of our recent studies of NifEN, with a focus on the implications of its functional versatility for nitrogenase assembly, catalysis and evolution.
钼固氮酶在其催化组分NifDK的辅因子处催化N还原为NH。NifEN在一级序列、三级结构和相关金属中心方面与NifDK具有相当大的同源性。NifEN以其将全铁前体（L-簇；[FeSC]）转化为成熟辅因子（M-簇；[(R-高柠檬酸)MoFeSC]）的生物合成功能而闻名，它在环境条件下催化底物还原方面也模仿NifDK。最近发现NifEN将N还原为NH的能力特别有趣，因为这表明NifEN在进化过程中是一种合理的、原型古老固氮酶。此外，NifEN在组装和催化方面的双重功能使其成为重建NifDK功能变体或等效物的理想模板，这有助于固氮酶的机制研究和异源合成。本综述概述了我们最近对NifEN的研究，重点是其功能多样性对固氮酶组装、催化和进化的影响。
