KEGG   PATHWAY: aqs00020
Entry
aqs00020                    Pathway                                
Name
Citrate cycle (TCA cycle) - Aquitalea sp. USM4
Description
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].
Class
Metabolism; Carbohydrate metabolism
Pathway map
aqs00020  Citrate cycle (TCA cycle)
aqs00020

Module
aqs_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:aqs00020]
aqs_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:aqs00020]
aqs_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:aqs00020]
aqs_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:aqs00020]
Other DBs
GO: 0006099
Organism
Aquitalea sp. USM4 [GN:aqs]
Gene
DKK66_03095  gltA; citrate (Si)-synthase [KO:K01647] [EC:2.3.3.1]
DKK66_18310  acnB; bifunctional aconitate hydratase 2/2-methylisocitrate dehydratase [KO:K01682] [EC:4.2.1.3 4.2.1.99]
DKK66_10585  NADP-dependent isocitrate dehydrogenase [KO:K00031] [EC:1.1.1.42]
DKK66_10590  NADP-dependent isocitrate dehydrogenase [KO:K00031] [EC:1.1.1.42]
DKK66_03090  sucA; 2-oxoglutarate dehydrogenase E1 component [KO:K00164] [EC:1.2.4.2]
DKK66_03085  2-oxoglutarate dehydrogenase complex dihydrolipoyllysine-residue succinyltransferase [KO:K00658] [EC:2.3.1.61]
DKK66_03075  lpdA; dihydrolipoyl dehydrogenase [KO:K00382] [EC:1.8.1.4]
DKK66_08560  lpdA; dihydrolipoyl dehydrogenase [KO:K00382] [EC:1.8.1.4]
DKK66_03065  succinate--CoA ligase subunit alpha [KO:K01902] [EC:6.2.1.5]
DKK66_03070  ADP-forming succinate--CoA ligase subunit beta [KO:K01903] [EC:6.2.1.5]
DKK66_02465  propionyl-CoA--succinate CoA transferase [KO:K18118] [EC:2.8.3.18]
DKK66_03110  sdhA; succinate dehydrogenase flavoprotein subunit [KO:K00239] [EC:1.3.5.1]
DKK66_03105  sdhB; succinate dehydrogenase iron-sulfur subunit [KO:K00240] [EC:1.3.5.1]
DKK66_03120  sdhC; succinate dehydrogenase, cytochrome b556 subunit [KO:K00241]
DKK66_03115  sdhD; succinate dehydrogenase, hydrophobic membrane anchor protein [KO:K00242]
DKK66_12395  fumarate hydratase [KO:K01676] [EC:4.2.1.2]
DKK66_03130  malate dehydrogenase [KO:K00024] [EC:1.1.1.37]
DKK66_08550  aceE; pyruvate dehydrogenase (acetyl-transferring), homodimeric type [KO:K00163] [EC:1.2.4.1]
DKK66_08555  aceF; dihydrolipoyllysine-residue acetyltransferase [KO:K00627] [EC:2.3.1.12]
Compound
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
Reference
  Authors
Nishizuka Y (ed).
  Title
[Metabolic Maps] (In Japanese)
  Journal
Tokyo Kagaku Dojin (1980)
Reference
  Authors
Nishizuka Y, Seyama Y, Ikai A, Ishimura Y, Kawaguchi A (eds).
  Title
[Cellular Functions and Metabolic Maps] (In Japanese)
  Journal
Tokyo Kagaku Dojin (1997)
Reference
  Authors
Michal G.
  Title
Biochemical Pathways
  Journal
Wiley (1999)
Related
pathway
aqs00010  Glycolysis / Gluconeogenesis
aqs00053  Ascorbate and aldarate metabolism
aqs00061  Fatty acid biosynthesis
aqs00071  Fatty acid degradation
aqs00190  Oxidative phosphorylation
aqs00220  Arginine biosynthesis
aqs00250  Alanine, aspartate and glutamate metabolism
aqs00280  Valine, leucine and isoleucine degradation
aqs00350  Tyrosine metabolism
aqs00470  D-Amino acid metabolism
aqs00630  Glyoxylate and dicarboxylate metabolism
KO pathway
ko00020   
LinkDB

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