Fig. 4.

The central carbon and energy metabolism of M. gorgona MG08 as predicted from its genome and confirmed by proteomics. H₄MPT, tetrahydromethanopterin. Dashed black arrows indicate passive diffusion across the cell membrane. Numbers for the metabolic steps in the figure refer to the following enzyme names: (1) particulate methane monooxygenase, (2) methanol dehydrogenase and corresponding cytochrome c, (3) formaldehyde activating enzyme, (4) NAD(P)-dependent methylene tetrahydromethanopterin dehydrogenase, (5) methenyl tetrahydromethanopterin cyclohydrolase, (6) formyltransferase/hydrolase, (7A) NAD-dependent formate dehydrogenase, (7B) molybdopterin binding reversible formate dehydrogenase/CO₂ reductase, (8) formate-tetrahydrofolate ligase, (9) bifunctional 5,10-methylene-tetrahydrofolate dehydrogenase and 5,10-methylene-tetrahydrofolate cyclohydrolase, (10) glycine cleavage system, (11) serine hydroxymethyltransferase, (12) serine–glyoxylate aminotransferase, (13) hydroxypyruvate reductase, (14) 2-glycerate kinase, (15) enolase, (16) phosphoenolpyruvate carboxylase, (17) malate dehydrogenase, (18) malate thiokinase, (19) malyl-CoA lyase, (20) carbonic anhydrase, (21) acetyl-CoA carboxylase, (22) [MuCo] class I carbon monoxide dehydrogenase, (23) cytochrome c reductase and corresponding cytochrome c, (24) cytochrome c/d/o terminal oxidases (cytochrome d oxidase—cydAB, cytochrome o ubiquinol oxidase—cyoABCD, heme-copper cytochrome c oxidase type A1 – ctaAEGBC, heme-copper cytochrome type C cbb₃ oxidase—ccoNOQP and heme-copper cytochrome c oxidase type A1—coxCAB). (25) [NiFe] group 1h hydrogenase, (26) NADH dehydrogenase, (27) ATP synthase, (28) nitrogenase, (29) ferredoxin, 2Fe-2S, and (30) ferredoxin-NADP⁺ oxidoreductase. All enzymes and electron carrier proteins were also detected in the proteome, with the exception of the nitrogenase and the cbb₃ oxidase. A full list of the proteins, corresponding genes, and genome entries are found in SI Appendix, Table S1.