ENTRY       ath00020                    Pathway
NAME        Citrate cycle (TCA cycle) - Arabidopsis thaliana (thale cress)
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 ath00020  Citrate cycle (TCA cycle)
MODULE      ath_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:ath00020]
            ath_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:ath00020]
            ath_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:ath00020]
            ath_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:ath00020]
            ath_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:ath00020]
DBLINKS     GO: 0006099
ORGANISM    Arabidopsis thaliana (thale cress) [GN:ath]
GENE        AT2G42790  CSY3; citrate synthase 3 [KO:K01647] [EC:2.3.3.1]
            AT3G58740  CSY1; citrate synthase 1 [KO:K01647] [EC:2.3.3.1]
            AT3G58750  CSY2; citrate synthase 2 [KO:K01647] [EC:2.3.3.1]
            AT3G60100  CSY5; citrate synthase 5 [KO:K01647] [EC:2.3.3.1]
            AT2G44350  ATCS; Citrate synthase family protein [KO:K01647] [EC:2.3.3.1]
            AT3G06650  ACLB-1; ATP-citrate lyase B-1 [KO:K01648] [EC:2.3.3.8]
            AT5G49460  ACLB-2; ATP citrate lyase subunit B 2 [KO:K01648] [EC:2.3.3.8]
            AT1G60810  ACLA-2; ATP-citrate lyase A-2 [KO:K01648] [EC:2.3.3.8]
            AT1G10670  ACLA-1; ATP-citrate lyase A-1 [KO:K01648] [EC:2.3.3.8]
            AT1G09430  ACLA-3; ATP-citrate lyase A-3 [KO:K01648] [EC:2.3.3.8]
            AT4G35830  ACO1; aconitase 1 [KO:K01681] [EC:4.2.1.3]
            AT2G05710  ACO3; aconitase 3 [KO:K01681] [EC:4.2.1.3]
            AT4G26970  ACO2; aconitase 2 [KO:K01681] [EC:4.2.1.3]
            AT1G65930  cICDH; cytosolic NADP+-dependent isocitrate dehydrogenase [KO:K00031] [EC:1.1.1.42]
            AT1G54340  ICDH; isocitrate dehydrogenase [KO:K00031] [EC:1.1.1.42]
            AT5G14590  Isocitrate/isopropylmalate dehydrogenase family protein [KO:K00031] [EC:1.1.1.42]
            AT4G35650  IDH-III; isocitrate dehydrogenase III [KO:K00030] [EC:1.1.1.41]
            AT5G03290  IDH-V; isocitrate dehydrogenase V [KO:K00030] [EC:1.1.1.41]
            AT2G17130  IDH2; isocitrate dehydrogenase subunit 2 [KO:K00030] [EC:1.1.1.41]
            AT4G35260  IDH1; isocitrate dehydrogenase 1 [KO:K00030] [EC:1.1.1.41]
            AT3G09810  IDH-VI; isocitrate dehydrogenase VI [KO:K00030] [EC:1.1.1.41]
            AT1G32480  IDH-IV; isocitrate dehydrogenase IV [KO:K00030] [EC:1.1.1.41]
            AT3G55410  2-oxoglutarate dehydrogenase, E1 component [KO:K00164] [EC:1.2.4.2]
            AT5G65750  2-oxoglutarate dehydrogenase, E1 component [KO:K00164] [EC:1.2.4.2]
            AT5G55070  Dihydrolipoamide succinyltransferase [KO:K00658] [EC:2.3.1.61]
            AT4G26910  Dihydrolipoamide succinyltransferase [KO:K00658] [EC:2.3.1.61]
            AT3G17240  mtLPD2; lipoamide dehydrogenase 2 [KO:K00382] [EC:1.8.1.4]
            AT3G16950  LPD1; lipoamide dehydrogenase 1 [KO:K00382] [EC:1.8.1.4]
            AT1G48030  mtLPD1; mitochondrial lipoamide dehydrogenase 1 [KO:K00382] [EC:1.8.1.4]
            AT4G16155  dihydrolipoamide dehydrogenase [KO:K00382] [EC:1.8.1.4]
            AT5G08300  Succinyl-CoA ligase, alpha subunit [KO:K01899] [EC:6.2.1.4 6.2.1.5]
            AT5G23250  Succinyl-CoA ligase, alpha subunit [KO:K01899] [EC:6.2.1.4 6.2.1.5]
            AT2G20420  ATP citrate lyase (ACL) family protein [KO:K01900] [EC:6.2.1.4 6.2.1.5]
            AT5G66760  SDH1-1; succinate dehydrogenase 1-1 [KO:K00234] [EC:1.3.5.1]
            AT2G18450  SDH1-2; succinate dehydrogenase 1-2 [KO:K00234] [EC:1.3.5.1]
            AT5G40650  SDH2-2; succinate dehydrogenase 2-2 [KO:K00235] [EC:1.3.5.1]
            AT5G65165  SDH2-3; succinate dehydrogenase 2-3 [KO:K00235] [EC:1.3.5.1]
            AT3G27380  SDH2-1; succinate dehydrogenase 2-1 [KO:K00235] [EC:1.3.5.1]
            AT4G32210  SDH3-2; succinate dehydrogenase 3-2 [KO:K00236]
            AT5G09600  SDH3-1; succinate dehydrogenase 3-1 [KO:K00236]
            AT2G46505  SDH4; succinate dehydrogenase subunit 4 [KO:K25801]
            AT5G50950  FUM2; FUMARASE 2 [KO:K01679] [EC:4.2.1.2]
            AT2G47510  FUM1; fumarase 1 [KO:K01679] [EC:4.2.1.2]
            AT1G04410  c-NAD-MDH1; Lactate/malate dehydrogenase family protein [KO:K00025] [EC:1.1.1.37]
            AT5G56720  c-NAD-MDH3; Lactate/malate dehydrogenase family protein [KO:K00025] [EC:1.1.1.37]
            AT5G43330  c-NAD-MDH2; Lactate/malate dehydrogenase family protein [KO:K00025] [EC:1.1.1.37]
            AT3G47520  MDH; malate dehydrogenase [KO:K00026] [EC:1.1.1.37]
            AT1G53240  mMDH1; Lactate/malate dehydrogenase family protein [KO:K00026] [EC:1.1.1.37]
            AT2G22780  PMDH1; peroxisomal NAD-malate dehydrogenase 1 [KO:K00026] [EC:1.1.1.37]
            AT3G15020  mMDH2; Lactate/malate dehydrogenase family protein [KO:K00026] [EC:1.1.1.37]
            AT5G09660  PMDH2; peroxisomal NAD-malate dehydrogenase 2 [KO:K00026] [EC:1.1.1.37]
            AT5G65690  PCK2; phosphoenolpyruvate carboxykinase 2 [KO:K01610] [EC:4.1.1.49]
            AT4G37870  PCK1; phosphoenolpyruvate carboxykinase 1 [KO:K01610] [EC:4.1.1.49]
            AT1G59900  E1_ALPHA; pyruvate dehydrogenase complex E1 alpha subunit [KO:K00161] [EC:1.2.4.1]
            AT1G01090  PDH-E1_ALPHA; pyruvate dehydrogenase E1 alpha [KO:K00161] [EC:1.2.4.1]
            AT1G24180  IAR4; thiamine diphosphate-binding fold (THDP-binding) superfamily protein [KO:K00161] [EC:1.2.4.1]
            AT5G50850  MAB1; Transketolase family protein [KO:K00162] [EC:1.2.4.1]
            AT2G34590  Transketolase family protein [KO:K00162] [EC:1.2.4.1]
            AT1G30120  PDH-E1_BETA; pyruvate dehydrogenase E1 beta [KO:K00162] [EC:1.2.4.1]
            AT1G34430  EMB3003; 2-oxoacid dehydrogenases acyltransferase family protein [KO:K00627] [EC:2.3.1.12]
            AT3G52200  LTA3; Dihydrolipoamide acetyltransferase, long form protein [KO:K00627] [EC:2.3.1.12]
            AT1G54220  Dihydrolipoamide acetyltransferase, long form protein [KO:K00627] [EC:2.3.1.12]
            AT3G13930  Dihydrolipoamide acetyltransferase, long form protein [KO:K00627] [EC:2.3.1.12]
            AT3G25860  LTA2; 2-oxoacid dehydrogenases acyltransferase family protein [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)
REL_PATHWAY ath00010  Glycolysis / Gluconeogenesis
            ath00053  Ascorbate and aldarate metabolism
            ath00061  Fatty acid biosynthesis
            ath00062  Fatty acid elongation
            ath00071  Fatty acid degradation
            ath00190  Oxidative phosphorylation
            ath00220  Arginine biosynthesis
            ath00250  Alanine, aspartate and glutamate metabolism
            ath00280  Valine, leucine and isoleucine degradation
            ath00350  Tyrosine metabolism
            ath00470  D-Amino acid metabolism
            ath00630  Glyoxylate and dicarboxylate metabolism
KO_PATHWAY  ko00020
///
