Assimilatory sulfate reduction in the marine methanogen Methanothermococcus thermolithotrophicus.

Methanothermococcus thermolithotrophicus is the only known methanogen that grows on sulfate as its sole sulfur source, uniquely uniting methanogenesis and sulfate reduction. Here we use physiological, biochemical and structural analyses to provide a snapshot of the complete sulfate reduction pathway of this methanogenic archaeon. We find that later steps in this pathway are catalysed by atypical enzymes.

Structures of the sulfite detoxifying F-dependent enzyme from Methanococcales.

Methanogenic archaea are main actors in the carbon cycle but are sensitive to reactive sulfite. Some methanogens use a sulfite detoxification system that combines an FH-oxidase with a sulfite reductase, both of which are proposed precursors of modern enzymes. Here, we present snapshots of this coupled system, named coenzyme F-dependent sulfite reductase (Group I Fsr), obtained from two marine methanogens.

CO-Fixation Strategies in Energy Extremophiles: What Can We Learn From Acetogens?

Domestication of CO-fixation became a worldwide priority enhanced by the will to convert this greenhouse gas into fuels and valuable chemicals. Because of its high stability, CO-activation/fixation represents a true challenge for chemists. Autotrophic microbial communities, however, perform these reactions under standard temperature and pressure.