Coupling of ferredoxin and heterodisulfide reduction via electron bifurcation in hydrogenotrophic methanogenic archaea

Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):2981-6. doi: 10.1073/pnas.1016761108. Epub 2011 Jan 24.


In methanogenic archaea growing on H(2) and CO(2) the first step in methanogenesis is the ferredoxin-dependent endergonic reduction of CO(2) with H(2) to formylmethanofuran and the last step is the exergonic reduction of the heterodisulfide CoM-S-S-CoB with H(2) to coenzyme M (CoM-SH) and coenzyme B (CoB-SH). We recently proposed that in hydrogenotrophic methanogens the two reactions are energetically coupled via the cytoplasmic MvhADG/HdrABC complex. It is reported here that the purified complex from Methanothermobacter marburgensis catalyzes the CoM-S-S-CoB-dependent reduction of ferredoxin with H(2). Per mole CoM-S-S-CoB added, 1 mol of ferredoxin (Fd) was reduced, indicating an electron bifurcation coupling mechanism: 2H(2) + Fd(OX) + CoM-S-S-CoB-->Fd(red)(2-) + CoM-SH + CoB-SH + 2H(+). This stoichiometry of coupling is consistent with an ATP gain per mole methane from 4 H(2) and CO(2) of near 0.5 deduced from an H(2)-threshold concentration of 8 Pa and a growth yield of up to 3 g/mol methane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Dioxide / metabolism*
  • Chromatography, High Pressure Liquid
  • Disulfides / metabolism*
  • Ferredoxins / metabolism*
  • Hydrogen / metabolism*
  • Magnetic Resonance Spectroscopy
  • Mesna / metabolism
  • Methane / biosynthesis*
  • Methanobacteriaceae / metabolism*
  • Metronidazole
  • Oxidation-Reduction
  • Phosphothreonine / analogs & derivatives
  • Phosphothreonine / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization


  • Disulfides
  • Ferredoxins
  • 7-mercaptoheptanoylthreonine phosphate
  • Phosphothreonine
  • Metronidazole
  • Carbon Dioxide
  • Hydrogen
  • Mesna
  • Methane