Electron flow in hydrogenotrophic methanogens under nickel limitation

• 成果类型: Article
• 署名作者: Nomura, Shunsuke; San Segundo-Acosta, Pablo; Protasov, Evgenii; Kaneko, Masanori; Kahnt, Joerg; Murphy, Bonnie J.; Shima, Seigo
• 署名单位: Max Planck Society; Max Planck Society; Centro Nacional de Investigaciones Oncologicas (CNIO); National Institute of Advanced Industrial Science & Technology (AIST); Max Planck Society
• 刊物名称: NATURE
• ISSN/ISSBN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-025-09229-y
• 发表日期: 2025-08-01
• 关键词: H-2-FORMING METHYLENETETRAHYDROMETHANOPTERIN DEHYDROGENASE; methanobacterium-thermoautotrophicum; cryo-em; methyltransferase complex; hydrogenase; reductase; enzyme; gene; POLYFERREDOXIN; bifurcation

摘要

Methanogenic archaea are the main producers of the potent greenhouse gas methane(1,2). In the methanogenic pathway from CO2 and H-2 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)(3-5). F-420-reducing [NiFe]-hydrogenase (Frh) provides electrons to the methanogenic pathway through the electron carrier F-420 (ref.(6)). Here we report that under strictly nickel-limited conditions, in which the nickel concentration is similar to those often observed in natural habitats(7-11), 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 F-420-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.