KEGG   PATHWAY: ate00020Help
ate00020                    Pathway                                

Citrate cycle (TCA cycle) - Caldicellulosiruptor bescii
The citrate cycle (TCA cycle, Krebs cycle) is an important aerobic pathway for the final steps of the oxidation of carbohydrates and fatty acids. The cycle starts with acetyl-CoA, the activated form of acetate, derived from glycolysis and pyruvate oxidation for carbohydrates and from beta oxidation of fatty acids. The two-carbon acetyl group in acetyl-CoA is transferred to the four-carbon compound of oxaloacetate to form the six-carbon compound of citrate. In a series of reactions two carbons in citrate are oxidized to CO2 and the reaction pathway supplies NADH for use in the oxidative phosphorylation and other metabolic processes. The pathway also supplies important precursor metabolites including 2-oxoglutarate. At the end of the cycle the remaining four-carbon part is transformed back to oxaloacetate. According to the genome sequence data, many organisms seem to lack genes for the full cycle [MD:M00009], but contain genes for specific segments [MD:M00010 M00011].
Metabolism; Carbohydrate metabolism
BRITE hierarchy
Pathway map
ate00020  Citrate cycle (TCA cycle)

Ortholog table
ate_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:ate00020]
ate_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:ate00020]
Other DBs
BSID: 82676
GO: 0006099
Caldicellulosiruptor bescii [GN:ate]
Athe_0518  pyruvate carboxyltransferase [KO:K05942] [EC:]
Athe_0524  aconitate hydratase [KO:K01681] [EC:]
Athe_0525  Isocitrate dehydrogenase (NAD(+)) [KO:K00030] [EC:]
Athe_0703  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Athe_1096  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00174] [EC:]
Athe_1097  thiamine pyrophosphate protein domain protein TPP-binding [KO:K00175] [EC:]
Athe_1098  pyruvate ferredoxin/flavodoxin oxidoreductase [KO:K00177] [EC:]
Athe_1095  4Fe-4S ferredoxin iron-sulfur binding domain protein [KO:K00176] [EC:]
Athe_2084  fumarate reductase/succinate dehydrogenase flavoprotein domain protein [KO:K00239] [EC:]
Athe_2746  hydro-lyase, Fe-S type, tartrate/fumarate subfamily, alpha subunit [KO:K01677] [EC:]
Athe_0510  hydro-lyase, Fe-S type, tartrate/fumarate subfamily, beta subunit [KO:K01678] [EC:]
Athe_0393  Phosphoenolpyruvate carboxykinase (GTP) [KO:K01596] [EC:]
Athe_0702  catalytic domain of components of various dehydrogenase complexes [KO:K00627] [EC:]
Athe_1708  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00169] [EC:]
Athe_0876  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00169] [EC:]
Athe_0877  thiamine pyrophosphate protein domain protein TPP-binding [KO:K00170] [EC:]
Athe_1709  pyruvate/ketoisovalerate oxidoreductase, gamma subunit [KO:K00172] [EC:]
Athe_0874  pyruvate/ketoisovalerate oxidoreductase, gamma subunit [KO:K00172] [EC:]
Athe_0875  pyruvate ferredoxin/flavodoxin oxidoreductase, delta subunit [KO:K00171] [EC:]
C00022  Pyruvate
C00024  Acetyl-CoA
C00026  2-Oxoglutarate
C00036  Oxaloacetate
C00042  Succinate
C00068  Thiamin diphosphate
C00074  Phosphoenolpyruvate
C00091  Succinyl-CoA
C00122  Fumarate
C00149  (S)-Malate
C00158  Citrate
C00311  Isocitrate
C00417  cis-Aconitate
C05125  2-(alpha-Hydroxyethyl)thiamine diphosphate
C05379  Oxalosuccinate
C05381  3-Carboxy-1-hydroxypropyl-ThPP
C15972  Enzyme N6-(lipoyl)lysine
C15973  Enzyme N6-(dihydrolipoyl)lysine
C16254  [Dihydrolipoyllysine-residue succinyltransferase] S-succinyldihydrolipoyllysine
C16255  [Dihydrolipoyllysine-residue acetyltransferase] S-acetyldihydrolipoyllysine
(map 2)
Nishizuka Y (ed).
[Metabolic Maps] (In Japanese)
Tokyo Kagaku Dojin (1980)
(map 3)
Nishizuka Y, Seyama Y, Ikai A, Ishimura Y, Kawaguchi A (eds).
[Cellular Functions and Metabolic Maps] (In Japanese)
Tokyo Kagaku Dojin (1997)
Michal G.
Biochemical Pathways
Wiley (1999)
KO pathway
LinkDB All DBs

DBGET integrated database retrieval system