Contribution of Transcriptomics to Systems-Level Understanding of Methanogenic Archaea

Figure 1

Overview of the three major known methanogenic pathways in Archaea. Color coding indicates the steps common to all three types (black), unique to the methylotrophic pathway (green), unique to the hydrogenotrophic (or CO₂ reducing) pathway (blue), unique to the aceticlastic pathway (red), and shared between hydrogenotrophic and aceticlastic methanogenesis (purple). 2e⁻ represents reducing equivalents, produced or consumed during each reaction. MFR: methanofuran; H₄MPT: tetrahydromethanopterin; CoM-SH: coenzyme M; CoB-SH: coenzyme B; CoA-SH: coenzyme A; CoM-S-S-CoB: heterodisulfide of coenzyme M and coenzyme B; ATP: adenosine triphosphate; R: ligand bound to methylated compound that serves as substrate for methylotrophic methanogenesis. *Tetrahydrosarcinapterin is a functional analogue of H₄MPT found in the Methanosarcinales order of methanogens.