KEGG   PATHWAY: sna00020Help
sna00020                    Pathway                                

Citrate cycle (TCA cycle) - Stackebrandtia nassauensis
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
sna00020  Citrate cycle (TCA cycle)

Ortholog table
sna_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:sna00020]
sna_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:sna00020]
sna_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:sna00020]
sna_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:sna00020]
sna_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:sna00020]
Other DBs
GO: 0006099
Stackebrandtia nassauensis [GN:sna]
Snas_3093  Citrate (Si)-synthase [KO:K01647] [EC:]
Snas_1016  Citrate (Si)-synthase [KO:K01647] [EC:]
Snas_3033  aconitate hydratase 1 [KO:K01681] [EC:]
Snas_1222  isocitrate dehydrogenase, NADP-dependent [KO:K00031] [EC:]
Snas_4200  2-oxoglutarate dehydrogenase, E2 component, dihydrolipoamide succinyltransferase [KO:K00658] [EC:]
Snas_4199  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Snas_0552  pyruvate flavodoxin/ferredoxin oxidoreductase domain protein [KO:K00174] [EC:]
Snas_0553  thiamine pyrophosphate protein domain protein TPP-binding protein [KO:K00175] [EC:]
Snas_0605  succinyl-CoA synthetase, alpha subunit [KO:K01902] [EC:]
Snas_0604  succinyl-CoA synthetase, beta subunit [KO:K01903] [EC:]
Snas_5227  succinate dehydrogenase or fumarate reductase, flavoprotein subunit [KO:K00239] [EC:]
Snas_5518  Succinate dehydrogenase [KO:K00239] [EC:]
Snas_5228  4Fe-4S ferredoxin iron-sulfur binding domain protein [KO:K00240] [EC:]
Snas_5519  succinate dehydrogenase and fumarate reductase iron-sulfur protein [KO:K00240] [EC:]
Snas_5226  succinate dehydrogenase (or fumarate reductase) cytochrome b subunit, b558 family [KO:K00241]
Snas_6383  hydro-lyase, Fe-S type, tartrate/fumarate subfamily, beta subunit [KO:K01676] [EC:]
Snas_0839  fumarate lyase [KO:K01679] [EC:]
Snas_0615  Lactate/malate dehydrogenase [KO:K00024] [EC:]
Snas_0731  Phosphoenolpyruvate carboxykinase (GTP) [KO:K01596] [EC:]
Snas_4794  2-oxo-acid dehydrogenase E1 subunit, homodimeric type [KO:K00163] [EC:]
Snas_6068  pyruvate dehydrogenase (acetyl-transferring) E1 component, alpha subunit [KO:K00161] [EC:]
Snas_3466  pyruvate dehydrogenase (acetyl-transferring) E1 component, alpha subunit [KO:K00161] [EC:]
Snas_6069  Transketolase central region [KO:K00162] [EC:]
Snas_3467  Transketolase central region [KO:K00162] [EC:]
Snas_6070  catalytic domain of components of various dehydrogenase complexes [KO:K00627] [EC:]
Snas_3468  Dihydrolipoyllysine-residue(2-methylpropanoyl) transferase [KO:K00627] [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)
sna00010  Glycolysis / Gluconeogenesis
sna00053  Ascorbate and aldarate metabolism
sna00061  Fatty acid biosynthesis
sna00071  Fatty acid degradation
sna00220  Arginine biosynthesis
sna00250  Alanine, aspartate and glutamate metabolism
sna00280  Valine, leucine and isoleucine degradation
sna00350  Tyrosine metabolism
sna00471  D-Glutamine and D-glutamate metabolism
sna00630  Glyoxylate and dicarboxylate metabolism
KO pathway
LinkDB All DBs

DBGET integrated database retrieval system