Diversity of electron-bifurcating CO₂-fixing supercomplexes in methanogens.

Authors

Pablo San Segundo-Acosta, Shunsuke Nomura, Joao Pedro Fernandes-Queiroz, Evgenii Protasov, Jörg Kahnt, Masanori Kaneko, Georg Hochberg, Seigo Shima, Bonnie J Murphy

Published in

Science advances. Volume 12. Issue 38. Pages eaed3711. Sep 18, 2026. Epub Sep 16, 2026.

Abstract

In the hydrogenotrophic methanogenic pathway, formylmethanofuran dehydrogenase (Fmd) reduces and fixes CO₂, driven by low-potential electrons provided by electron-bifurcating heterodisulfide reductase (Hdr) complexed with electron-donating proteins such as Mvh hydrogenase. Here, we report the structure of a C2-symmetric (Mvh-Hdr)₂-Fmd₄ supercomplex from a Class I methanogen, Methanothermobacter marburgensis, which is architecturally different from the previously reported ring-shaped D3-symmetric supercomplex of a methanogen belonging to phylogenetically distinct Class II methanogens. In this C2-symmetric form, the redox active sites of Hdr and Fmd are connected by two MvhB polyferredoxins, whose branching electron paths appear to be available for electron transfer to/from other partners. The ancestral form was likely C2 symmetric, whereas D3-symmetric supercomplexes were acquired by horizontal gene transfer, a transition probably helpful for growth in substrate-poor environments.

PMID:
42748252
Bibliographic data and abstract were imported from PubMed on 17 Sep 2026.

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