KEGG   PATHWAY: ctl00020
Entry
ctl00020                    Pathway                                
Name
Citrate cycle (TCA cycle) - Chlamydia trachomatis L2b/UCH-1/proctitis
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
ctl00020  Citrate cycle (TCA cycle)
ctl00020

Module
ctl_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:ctl00020]
Other DBs
GO: 0006099
Organism
Chlamydia trachomatis L2b/UCH-1/proctitis [GN:ctl]
Gene
CTLon_0305  sucA; 2-oxoglutarate dehydrogenase E1 component [KO:K00164] [EC:1.2.4.2]
CTLon_0653  sucB; lipoamide acyltransferase component (E2) of branched-chain alpha-keto acid dehydrogenase complex [KO:K00658] [EC:2.3.1.61]
CTLon_0306  sucB; dihydrolipoamide succinyltransferase component (E2) of 2-oxoglutarate dehydrogenase complex [KO:K00658] [EC:2.3.1.61]
CTLon_0814  lpdA; dihydrolipoamide dehydrogenase [KO:K00382] [EC:1.8.1.4]
CTLon_0194  sucD; succinyl-CoA synthetase alpha chain [KO:K01902] [EC:6.2.1.5]
CTLon_0193  sucC; succinyl-CoA synthetase beta chain [KO:K01903] [EC:6.2.1.5]
CTLon_0849  sdhA; succinate dehydrogenase flavoprotein subunit [KO:K00239] [EC:1.3.5.1]
CTLon_0848  sdhB; succinate dehydrogenase iron-sulfur protein [KO:K00240] [EC:1.3.5.1]
CTLon_0628  mdhC; malate dehydrogenase [KO:K00024] [EC:1.1.1.37]
CTLon_0079  pckA; phosphoenolpyruvate carboxykinase (GTP) [KO:K01596] [EC:4.1.1.32]
CTLon_0493  pdhA; pyruvate dehydrogenase E1 component alpha subunit [KO:K00161] [EC:1.2.4.1]
CTLon_0494  pdhB; pyruvate dehydrogenase E1 component beta subunit [KO:K00162] [EC:1.2.4.1]
CTLon_0495  pdhC; dihydrolipoamide acetyltransferase component of pyruvate dehydrogenase complex [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
ctl00010  Glycolysis / Gluconeogenesis
ctl00061  Fatty acid biosynthesis
ctl00190  Oxidative phosphorylation
ctl00250  Alanine, aspartate and glutamate metabolism
ctl00280  Valine, leucine and isoleucine degradation
ctl00470  D-Amino acid metabolism
ctl00630  Glyoxylate and dicarboxylate metabolism
KO pathway
ko00020   
LinkDB

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