The missing enzymatic link in syntrophic methane formation from fatty acids

Agne, Michael; Estelmann, Sebastian; Seelmann, Carola S.; Kung, Johannes; Wilkens, Dennis; Koch, Hans-Georg; van der Does, Chris; Albers, Sonja V.; von Ballmoos, Christoph; Simon, Jörg; Boll, Matthias (2021). The missing enzymatic link in syntrophic methane formation from fatty acids. Proceedings of the National Academy of Sciences of the United States of America - PNAS, 118(40), e2111682118. National Academy of Sciences NAS 10.1073/pnas.2111682118

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The microbial production of methane from organic matter is an essential process in the global carbon cycle and an important source of renewable energy. It involves the syntrophic interaction between methanogenic archaea and bacteria that convert primary fermentation products such as fatty acids to the methanogenic substrates acetate, H2, CO2, or formate. While the concept of syntrophic methane formation was developed half a century ago, the highly endergonic reduction of CO2 to methane by electrons derived from β-oxidation of saturated fatty acids has remained hypothetical. Here, we studied a previously noncharacterized membrane-bound oxidoreductase (EMO) from Syntrophus aciditrophicus containing two heme b cofactors and 8-methylmenaquinone as key redox components of the redox loop-driven reduction of CO2 by acyl-coenzyme A (CoA). Using solubilized EMO and proteoliposomes, we reconstituted the entire electron transfer chain from acyl-CoA to CO2 and identified the transfer from a high- to a low-potential heme b with perfectly adjusted midpoint potentials as key steps in syntrophic fatty acid oxidation. The results close our gap of knowledge in the conversion of biomass into methane and identify EMOs as key players of β-oxidation in (methyl)menaquinone-containing organisms.

Item Type:

Journal Article (Original Article)


08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

von Ballmoos, Christoph


500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry




National Academy of Sciences NAS




Christina Schüpbach

Date Deposited:

01 Feb 2022 14:36

Last Modified:

05 Dec 2022 16:03

Publisher DOI:





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