KEGG   PATHWAY: atm00020
atm00020                    Pathway                                

Citrate cycle (TCA cycle) - Anaerolinea thermophila
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
Pathway map
atm00020  Citrate cycle (TCA cycle)

atm_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:atm00020]
atm_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:atm00020]
Other DBs
GO: 0006099
Anaerolinea thermophila [GN:atm]
ANT_12180  gltA; citrate synthase [KO:K01647] [EC:]
ANT_12140  citB; aconitate hydratase [KO:K01681] [EC:]
ANT_03940  isocitrate dehydrogenase [NADP] [KO:K00031] [EC:]
ANT_00050  lpd; dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
ANT_04500  putative 2-oxoglutarate ferredoxin oxidoreductase alpha subunit [KO:K00174] [EC:]
ANT_18150  putative 2-oxoglutarate ferredoxin oxidoreductase alpha subunit [KO:K00174] [EC:]
ANT_04510  putative 2-oxoglutarate ferredoxin oxidoreductase beta subunit [KO:K00175] [EC:]
ANT_18140  putative 2-oxoglutarate ferredoxin oxidoreductase beta subunit [KO:K00175] [EC:]
ANT_04520  putative 2-oxoglutarate ferredoxin oxidoreductase gamma subunit [KO:K00177] [EC:]
ANT_04490  putative 2-oxoglutarate ferredoxin oxidoreductase delta subunit [KO:K00176] [EC:]
ANT_20570  sucD; succinyl-CoA synthetase alpha chain [KO:K01902] [EC:]
ANT_20580  sucC; succinyl-CoA synthetase beta chain [KO:K01903] [EC:]
ANT_22150  sdhA; succinate dehydrogenase, flavoprotein subunit [KO:K00239] [EC:]
ANT_27590  sdhB; succinate dehydrogenase iron-sulfur subunit [KO:K00240] [EC:]
ANT_22140  sdhB; succinate dehydrogenase iron-sulfur subunit [KO:K00240] [EC:]
ANT_27580  sdhC; putative succinate dehydrogenase cytochrome b subunit [KO:K00241]
ANT_22170  sdhC; putative succinate dehydrogenase cytochrome b subunit [KO:K00241]
ANT_22160  sdhD; putative succinate dehydrogenase membrane subunit [KO:K00242]
ANT_27570  sdhD; putative succinate dehydrogenase membrane subunit [KO:K00242]
ANT_30960  class-I fumarase family protein [KO:K01676] [EC:]
ANT_30970  class-I fumarase family protein [KO:K01678] [EC:]
ANT_14590  pckA; phosphoenolpyruvate carboxykinase [ATP] [KO:K01610] [EC:]
ANT_14260  pdhA; putative pyruvate dehydrogenase E1 component alpha subunit [KO:K00161] [EC:]
ANT_14270  pdhB; putative pyruvate dehydrogenase E1 component beta subunit [KO:K00162] [EC:]
ANT_14280  pdhC; putative pyruvate dehydrogenase E2 component [KO:K00627] [EC:]
ANT_28320  putative pyruvate:ferredoxin oxidoreductase [KO:K03737] [EC: 1.2.7.-]
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)
atm00010  Glycolysis / Gluconeogenesis
atm00053  Ascorbate and aldarate metabolism
atm00061  Fatty acid biosynthesis
atm00071  Fatty acid degradation
atm00190  Oxidative phosphorylation
atm00220  Arginine biosynthesis
atm00250  Alanine, aspartate and glutamate metabolism
atm00280  Valine, leucine and isoleucine degradation
atm00350  Tyrosine metabolism
atm00471  D-Glutamine and D-glutamate metabolism
atm00630  Glyoxylate and dicarboxylate metabolism
KO pathway

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