KEGG   PATHWAY: ssg00020Help
Entry
ssg00020                    Pathway                                

Name
Citrate cycle (TCA cycle) - Selenomonas sputigena
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
BRITE hierarchy
Pathway map
Citrate cycle (TCA cycle)
ssg00020

All organismsOrtholog table
Module
Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:ssg00020]
Other DBs
BSID: 
GO: 
Organism
Selenomonas sputigena [GN:ssg]
Gene
Citrate synthase; K01647 citrate synthase [EC:2.3.3.1] [KO:K01647] [EC:2.3.3.1]
aconitate hydratase; K01681 aconitate hydratase [EC:4.2.1.3] [KO:K01681] [EC:4.2.1.3]
Isocitrate dehydrogenase (NAD(+)); K00030 isocitrate dehydrogenase (NAD+) [EC:1.1.1.41] [KO:K00030] [EC:1.1.1.41]
succinyl-CoA synthetase; K01902 succinyl-CoA synthetase alpha subunit [EC:6.2.1.5] [KO:K01902] [EC:6.2.1.5]
Succinyl-CoA ligase (ADP-forming) subunit beta; K01903 succinyl-CoA synthetase beta subunit [EC:6.2.1.5] [KO:K01903] [EC:6.2.1.5]
succinate CoA transferase; K18118 succinyl-CoA:acetate CoA-transferase [EC:2.8.3.18] [KO:K18118] [EC:2.8.3.18]
succinate dehydrogenase or fumarate reductase; K00239 succinate dehydrogenase flavoprotein subunit [EC:1.3.5.1] [KO:K00239] [EC:1.3.5.1]
succinate dehydrogenase and fumarate reductase iron-sulfur protein; K00240 succinate dehydrogenase iron-sulfur subunit [EC:1.3.5.1] [KO:K00240] [EC:1.3.5.1]
succinate dehydrogenase (or fumarate reductase) cytochrome b subunit; K00241 succinate dehydrogenase cytochrome b556 subunit [KO:K00241]
hydro-lyase; K01677 fumarate hydratase subunit alpha [EC:4.2.1.2] [KO:K01677] [EC:4.2.1.2]
hydro-lyase; K01678 fumarate hydratase subunit beta [EC:4.2.1.2] [KO:K01678] [EC:4.2.1.2]
Fumarate hydratase class II; K01679 fumarate hydratase, class II [EC:4.2.1.2] [KO:K01679] [EC:4.2.1.2]
Malate dehydrogenase; K00024 malate dehydrogenase [EC:1.1.1.37] [KO:K00024] [EC:1.1.1.37]
phosphoenolpyruvate carboxykinase (ATP); K01610 phosphoenolpyruvate carboxykinase (ATP) [EC:4.1.1.49] [KO:K01610] [EC:4.1.1.49]
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
(map 2)
  Authors
Nishizuka Y (ed).
  Title
[Metabolic Maps] (In Japanese)
  Journal
Tokyo Kagaku Dojin (1980)
Reference
(map 3)
  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)
KO pathway
 

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