KEGG   PATHWAY: reu00020
reu00020                    Pathway                                
Citrate cycle (TCA cycle) - Cupriavidus pinatubonensis JMP134
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
reu00020  Citrate cycle (TCA cycle)

reu_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:reu00020]
reu_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:reu00020]
reu_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:reu00020]
reu_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:reu00020]
reu_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:reu00020]
Other DBs
GO: 0006099
Cupriavidus pinatubonensis JMP134 [GN:reu]
Reut_A2320  citrate synthase [KO:K01647] [EC:]
Reut_C6294  citrate synthase [KO:K01647] [EC:]
Reut_C6318  citrate synthase [KO:K01647] [EC:]
Reut_C6352  citrate synthase [KO:K01647] [EC:]
Reut_A1760  Citrate synthase [KO:K01647] [EC:]
Reut_B3867  citrate synthase [KO:K01647] [EC:]
Reut_B4959  citrate synthase [KO:K01647] [EC:]
Reut_B4697  conserved hypothetical protein [KO:K01647] [EC:]
Reut_A1194  conserved hypothetical protein [KO:K01647] [EC:]
Reut_A2331  aconitase [KO:K01681] [EC:]
Reut_B3464  aconitase [KO:K01682] [EC:]
Reut_A2756  isocitrate dehydrogenase (NADP) [KO:K00031] [EC:]
Reut_B4201  Isocitrate dehydrogenase NADP-dependent, monomeric type [KO:K00031] [EC:]
Reut_B4481  2-oxoglutarate dehydrogenase E1 component [KO:K00164] [EC:]
Reut_A2047  2-oxoglutarate dehydrogenase E1 component [KO:K00164] [EC:]
Reut_A2046  2-oxoglutarate dehydrogenase E2 component [KO:K00658] [EC:]
Reut_A2045  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Reut_A1306  dihydrolipoamide dehydrogenase [KO:K00382] [EC:]
Reut_B4451  FAD-dependent pyridine nucleotide-disulfide oxidoreductase:Pyridine nucleotide-disulfide oxidoreductase dimerization region [KO:K00382] [EC:]
Reut_A0531  succinyl-CoA synthetase (ADP-forming) alpha subunit [KO:K01902] [EC:]
Reut_A0530  succinyl-CoA synthetase (ADP-forming) beta subunit [KO:K01903] [EC:]
Reut_A1290  Acetyl-CoA hydrolase [KO:K18118] [EC:]
Reut_A2323  succinate dehydrogenase subunit A [KO:K00239] [EC:]
Reut_A2322  succinate dehydrogenase subunit B [KO:K00240] [EC:]
Reut_A2325  succinate dehydrogenase subunit C [KO:K00241]
Reut_A2324  succinate dehydrogenase subunit D [KO:K00242]
Reut_A2232  fumarase [KO:K01676] [EC:]
Reut_B5517  fumarase [KO:K01679] [EC:]
Reut_A2327  malate dehydrogenase (NAD) [KO:K00024] [EC:]
Reut_B4717  Pyruvate carboxylase [KO:K01958] [EC:]
Reut_A3420  Phosphoenolpyruvate carboxykinase (GTP) [KO:K01596] [EC:]
Reut_A1303  2-oxo-acid dehydrogenase E1 component homodimeric type [KO:K00163] [EC:]
Reut_B4683  2-oxo-acid dehydrogenase E1 component homodimeric type [KO:K00163] [EC:]
Reut_B5552  Alpha/beta hydrolase fold:Biotin/lipoyl attachment [KO:K00627] [EC:]
Reut_A1304  Dihydrolipoamide acetyltransferase [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
Nishizuka Y (ed).
[Metabolic Maps] (In Japanese)
Tokyo Kagaku Dojin (1980)
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)
reu00010  Glycolysis / Gluconeogenesis
reu00053  Ascorbate and aldarate metabolism
reu00061  Fatty acid biosynthesis
reu00071  Fatty acid degradation
reu00190  Oxidative phosphorylation
reu00220  Arginine biosynthesis
reu00250  Alanine, aspartate and glutamate metabolism
reu00280  Valine, leucine and isoleucine degradation
reu00350  Tyrosine metabolism
reu00470  D-Amino acid metabolism
reu00630  Glyoxylate and dicarboxylate metabolism
KO pathway

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