Buckel Wolfgang, Ermler Ulrich, Vonck Janet, Fritz Günter, Steuber Julia
Faculty of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Straße 8, 35043, Marburg, Germany.
Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max-von-Laue-Straße 3, 60438, Frankfurt am Main, Germany.
Appl Microbiol Biotechnol. 2025 Jun 17;109(1):148. doi: 10.1007/s00253-025-13531-0.
The Na (or H)-translocating ferredoxin:NAD oxidoreductase (also called RNF, rhodobacter nitrogen fixation, complex) catalyzes the oxidation of reduced ferredoxin with NAD, hereby generating an electrochemical gradient. In the reverse reaction driven by an electrochemical gradient, RNF provides reduced ferredoxin using NADH as electron donor. RNF plays a crucial role in the metabolism of many anaerobes, such as amino acid fermenters, acetogens, or aceticlastic methanogens. The Na-translocating NADH:quinone oxidoreductase (NQR), which has evolved from an RNF, is found in selected bacterial groups including anaerobic, marine, or pathogenic organisms. Since NQR and RNF are not related to eukaryotic respiratory complex I (NADH:quinone oxidoreductase), members of this oxidoreductase family are promising targets for novel antibiotics. RNF and NQR share a membrane-bound core complex consisting of four subunits, which represent an essential functional module for redox-driven cation transport. Several recent 3D structures of RNF and NQR in different states put forward conformational coupling of electron transfer and Na translocation reaction steps. Based on this common principle, putative reaction mechanisms of RNF and NQR redox pumps are compared. KEY POINTS: • Electrogenic ferredoxin:NAD oxidoreductases (RNF complexes) are found in bacteria and archaea. • The Na -translocating NADH:quinone oxidoreductase (NQR) is evolutionary related to RNF. • The mechanism of energy conversion by RNF/NQR complexes is based on conformational coupling of electron transfer and cation transport reactions.
钠（或氢）转运型铁氧化还原蛋白：NAD氧化还原酶（也称为RNF，红细菌固氮复合体）催化还原型铁氧化还原蛋白与NAD的氧化反应，从而产生电化学梯度。在由电化学梯度驱动的逆向反应中，RNF以NADH作为电子供体提供还原型铁氧化还原蛋白。RNF在许多厌氧菌的代谢中起着关键作用，如氨基酸发酵菌、产乙酸菌或乙酸裂解产甲烷菌。从RNF进化而来的钠转运型NADH：醌氧化还原酶（NQR）存在于包括厌氧、海洋或致病生物在内的特定细菌群体中。由于NQR和RNF与真核生物呼吸复合体I（NADH：醌氧化还原酶）无关，该氧化还原酶家族的成员是新型抗生素的有前景的靶点。RNF和NQR共享一个由四个亚基组成的膜结合核心复合体，这是氧化还原驱动的阳离子转运的基本功能模块。最近几个处于不同状态的RNF和NQR的3D结构提出了电子转移和钠转运反应步骤的构象偶联。基于这一共同原理，比较了RNF和NQR氧化还原泵的推测反应机制。要点：• 产电铁氧化还原蛋白：NAD氧化还原酶（RNF复合体）存在于细菌和古细菌中。• 钠转运型NADH：醌氧化还原酶（NQR）与RNF在进化上相关。• RNF/NQR复合体的能量转换机制基于电子转移和阳离子转运反应的构象偶联。
