Figure 2
Inferred metabolism of C. autoethanogenum . Capital letters in brown denote enzymes. ATP, adenosine triphosphate, ADP, adenosine diphosphate; BDO, 2,3-butanediol; CO, carbon monoxide; CO2, carbon dioxide; FAD, flavin adenine dinucleotide; FADH2 FD_red, ferredoxin (reduced); FD_ox, ferredoxin (oxidized); G3P, 3-phosphoglycerate; GP, glycerone-phosphate; H3PO4, phosphate; NAD, nicotinamide adenine dinucleotide (oxidized); NADH, nicotinamide adenine dinucleotide (reduced); NADP, nicotinamide adenine dinucleotide phosphate (oxidized); NADPH, nicotinamide adenine dinucleotide phosphate (reduced); TCA, tricarboxcylic acid cycle. Note that reaction directionality has not been rigorously determined; in general, directionality is as reported in KEGG reactions. Acetyl-CoA (Wood-Ljungdahl) pathway – Reductive branch. W1 Bifunctional CO dehydrogenase/Acetyl-CoA synthase (CODH/ACS) CAETHG_1620-21, 1608-11, W2 Seleno formate dehydrogenase (Fdh) CAETHG_0084, 2789, W3 Non-seleno formate dehydrogenase (Fdh) CAETHG_2988, W4 Formyl-THF ligase (Fhs) CAETHG_1618, W5 Methenyl-THF cyclohydrolase (FchA) CAETHG_1617, W6 Methylene-THF dehydrogenase (FolD) CAETHG_1616, W7 Methylene-THF reductase (MetF) CAETHG_1614-15. Acetyl-CoA (Wood-Ljungdahl) pathway – Oxidative branch. C Monofunctional CO dehydrogenase CAETHG_3899, 3005, H1 Electron-bifurcating [FeFe] Hydrogenase (HytCBDE1AE2) CAETHG_2798, H2 Other [FeFe] hydrogenases (Hyd) CAETHG_0110, 0120, 1576, 3569, 3841, H3 [NiFe] hydrogenase (Hyd) CAETHG_0862, H4 Hydrogenase maturation factor (HypEDCF) CAETHG_0368-0371. Energy conservation. A F1FO ATPase (AtpIBEFHAGDC) CAETHG_2342-50, N Electron-bifurcating NADH-dependent Fd:NADP oxidoreductase (Nfn) CAETHG_1580, R Rnf complex (RnfCDGEAB) CAETHG_3227-32. Acetate fermentation pathway. Ac1 Phosphotransacetylase (Pta) CAETHG_3358, Ac2 Acetate kinase (Ack) CAETHG_3359. Ethanol fermentation pathway. E1 Bifunctional aldehyde/alcohol dehydrogenase (AdhE) CAETHG_3747, 3748, E2 Aldehyde:Fd oxidoreductase (AOR) CAETHG_0092, 0102, E3 Additional alcohol dehydrogenases (Adh) CAETHG_0555. 2,3-butanediol fermentation pathway. B1 Acetolactate synthase (AlsS) CAETHG_0124-25, 0406, 1740, B2 Acetolactate decarboxylase (BudA) CAETHG_2932, B3 2,3-butanediol dehydrogenase (Bdh) CAETHG_0385, Lactate fermentation pathway. L Lactate dehydrogenase (Ldh) CAETHG_1147. Central pyruvate metabolism. P1 Pyruvate:ferredoxin oxidoreductase (PFOR) CAETHG_0928, 3029, P2 Pyruvate, phosphate dikinase (PPDK) CAETHG_2055, 2909, P3 Pyruvate kinase (Pk) CAETHG_2440-41, P4 Pyruvate carboxylase (Pyc) CAETHG_1594, P5 PEP carboxykinase (PEPCK) CAETHG_2721, P5 Malic enzyme CAETHG_0605, 1055. Incomplete TCA cycle. T1 Citrate synthase CAETHG _2751, T2 Citrate lyase CAETHG_1052-54, 1898–1901, 2480-83, T3 Aconitase (Aco) CAETHG_1051, 2752, T4 Isocitrate dehydrogenase (Idh) CAETHG_2753, T5 Malate dehydrogenase (Mdh) CAETHG_1702, 2478, 2689, T6 Fumarase CAETHG_1902-03, 2062, 2479, T7 Fumarate reductase CAETHG_0344, 1032, 2961. Glycolysis/Gluconeogenesis. PTS Fructose phosphotransferase system (PTS) CAETHG_0142, 0676-73, G1 Fructokinase (Fk) /Fructose-6-phosphate isomerase CAETHG_0166, 0156, G2 1-phosphofructokinase (Pfk1) CAETHG_0143, G3 6-phosphofructokinase (Pfk6) CAETHG_648, 2439, G4 Fructose bisphosphate aldolase (Aldo) CAETHG_2382, G5 Triose-phosphate isomerase (Tpi) CAETHG_1758, G6 Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) CAETHG_1760, 3424, G7 Phosphoglycerate kinase (Pgk) CAETHG_1759, G8 Phosphoglycerate mutase (Pgm) CAETHG_712, 1757, G9 Enolase phosphopyruvate hydratase (Eno) CAETHG_1756.