德国马克斯·普朗克陆地微生物研究所Shima, Seigo研究组研究了镍限制下氢营养型产甲烷菌的电子流。相关论文于2025年7月2日发表在《自然》杂志上。

产甲烷古菌是强效温室气体甲烷的主要生产者。在实验室条件下研究的二氧化碳和氢气的产甲烷途径中，二氧化碳还原的低电势电子是由异二硫醚还原酶（Hdr）与相关的[NiFe]-氢化酶（Mvh）复合催化的黄素基电子分叉反应产生的。F₄₂₀还原[NiFe]-氢化酶（Frh）通过电子载体F₄₂₀为产甲烷途径提供电子。

研究组报道，在严格的镍限制条件下，镍浓度与自然栖息地中经常观察到的镍浓度相似，马堡甲烷嗜热杆菌中[NiFe]-氢化酶的产生强烈下调。Frh反应被与[Fe]-氢酶（Hmd）的偶联反应所取代，Mvh的作用被F₄₂₀依赖性供电子蛋白（Elp）所取代。因此，Hmd在这些镍限制条件下为还原代谢提供了所有电子。Elp-Hdr复合物的生化和结构特征证实了Elp和Hdr之间的电子相互作用。编码Elp和Hmd的基因在减少二氧化碳的氢营养型产甲烷菌中的保守性表明，Hmd系统是镍限制条件下减少二氧化碳氢营养型甲烷菌中电子流动的替代途径。

附：英文原文

Title: Electron flow in hydrogenotrophic methanogens under nickel limitation

Author: Nomura, Shunsuke, San Segundo-Acosta, Pablo, Protasov, Evgenii, Kaneko, Masanori, Kahnt, Jrg, Murphy, Bonnie J., Shima, Seigo

Issue&Volume: 2025-07-02

Abstract: Methanogenic archaea are the main producers of the potent greenhouse gas methane1,2. In the methanogenic pathway from CO2 and H2 studied under laboratory conditions, low-potential electrons for CO2 reduction are generated by a flavin-based electron-bifurcation reaction catalysed by heterodisulfide reductase (Hdr) complexed with the associated [NiFe]-hydrogenase (Mvh)3,4,5. F420-reducing [NiFe]-hydrogenase (Frh) provides electrons to the methanogenic pathway through the electron carrier F420 (ref.6). Here we report that under strictly nickel-limited conditions, in which the nickel concentration is similar to those often observed in natural habitats7,8,9,10,11, the production of both [NiFe]-hydrogenases in Methanothermobacter marburgensis is strongly downregulated. The Frh reaction is substituted by a coupled reaction with [Fe]-hydrogenase (Hmd), and the role of Mvh is taken over by F420-dependent electron-donating proteins (Elp). Thus, Hmd provides all electrons for the reducing metabolism under these nickel-limited conditions. Biochemical and structural characterization of Elp–Hdr complexes confirms the electronic interaction between Elp and Hdr. The conservation of the genes encoding Elp and Hmd in CO2-reducing hydrogenotrophic methanogens suggests that the Hmd system is an alternative pathway for electron flow in CO2-reducing hydrogenotrophic methanogens under nickel-limited conditions.

DOI: 10.1038/s41586-025-09229-y

Source: https://www.nature.com/articles/s41586-025-09229-y