The missing enzymatic link in syntrophic methane formation from fatty acids.
Proc Natl Acad Sci U S A
; 118(40)2021 10 05.
Article
in En
| MEDLINE
| ID: mdl-34583996
ABSTRACT
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 ß-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 ß-oxidation in (methyl)menaquinone-containing organisms.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacterial Proteins
/
Deltaproteobacteria
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Fatty Acids
/
Methane
Language:
En
Journal:
Proc Natl Acad Sci U S A
Year:
2021
Document type:
Article
Affiliation country: