ENTRY       mtr00020                    Pathway
NAME        Citrate cycle (TCA cycle) - Medicago truncatula (barrel medic)
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 mtr00020  Citrate cycle (TCA cycle)
MODULE      mtr_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:mtr00020]
            mtr_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:mtr00020]
            mtr_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:mtr00020]
            mtr_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:mtr00020]
            mtr_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:mtr00020]
DBLINKS     GO: 0006099
ORGANISM    Medicago truncatula (barrel medic) [GN:mtr]
GENE        11445289  citrate synthase, glyoxysomal isoform X1 [KO:K01647] [EC:2.3.3.1]
            11437065  citrate synthase, glyoxysomal [KO:K01647] [EC:2.3.3.1]
            25486862  citrate synthase, mitochondrial [KO:K01647] [EC:2.3.3.1]
            11413900  ATP-citrate synthase beta chain protein 1 [KO:K01648] [EC:2.3.3.8]
            11425415  ATP-citrate synthase alpha chain protein 2 [KO:K01648] [EC:2.3.3.8]
            11407101  ATP-citrate synthase alpha chain protein 1 isoform X2 [KO:K01648] [EC:2.3.3.8]
            11416041  aconitate hydratase, cytoplasmic [KO:K01681] [EC:4.2.1.3]
            11440920  aconitate hydratase, cytoplasmic [KO:K01681] [EC:4.2.1.3]
            11421844  aconitate hydratase 1 [KO:K01681] [EC:4.2.1.3]
            11445769  isocitrate dehydrogenase [NADP] [KO:K00031] [EC:1.1.1.42]
            11425956  isocitrate dehydrogenase [NADP], chloroplastic [KO:K00031] [EC:1.1.1.42]
            11419675  isocitrate dehydrogenase [NADP] [KO:K00031] [EC:1.1.1.42]
            11442733  isocitrate dehydrogenase [NAD] regulatory subunit 1, mitochondrial [KO:K00030] [EC:1.1.1.41]
            11420892  isocitrate dehydrogenase [NAD] catalytic subunit 5, mitochondrial [KO:K00030] [EC:1.1.1.41]
            11409879  isocitrate dehydrogenase [NAD] regulatory subunit 1, mitochondrial isoform X1 [KO:K00030] [EC:1.1.1.41]
            11434137  isocitrate dehydrogenase [NAD] catalytic subunit 5, mitochondrial [KO:K00030] [EC:1.1.1.41]
            25485706  2-oxoglutarate dehydrogenase, mitochondrial [KO:K00164] [EC:1.2.4.2]
            11443322  2-oxoglutarate dehydrogenase, mitochondrial [KO:K00164] [EC:1.2.4.2]
            11419773  dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex 1, mitochondrial [KO:K00658] [EC:2.3.1.61]
            11442277  dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex 1, mitochondrial [KO:K00658] [EC:2.3.1.61]
            11408806  dihydrolipoyl dehydrogenase 2, chloroplastic isoform X1 [KO:K00382] [EC:1.8.1.4]
            11422305  dihydrolipoyl dehydrogenase 1, chloroplastic [KO:K00382] [EC:1.8.1.4]
            25494137  dihydrolipoyl dehydrogenase, mitochondrial [KO:K00382] [EC:1.8.1.4]
            11414653  succinate--CoA ligase [ADP-forming] subunit alpha, mitochondrial [KO:K01899] [EC:6.2.1.4 6.2.1.5]
            25484225  succinate--CoA ligase [ADP-forming] subunit beta, mitochondrial [KO:K01900] [EC:6.2.1.4 6.2.1.5]
            11405633  succinate dehydrogenase [ubiquinone] flavoprotein subunit 1, mitochondrial [KO:K00234] [EC:1.3.5.1]
            25479657  succinate dehydrogenase [ubiquinone] iron-sulfur subunit 2, mitochondrial [KO:K00235] [EC:1.3.5.1]
            25485801  succinate dehydrogenase [ubiquinone] iron-sulfur subunit 2, mitochondrial [KO:K00235] [EC:1.3.5.1]
            11443418  uncharacterized protein LOC11443418 [KO:K00236]
            11436549  uncharacterized protein LOC11436549 isoform X1 [KO:K25801]
            11428376  fumarate hydratase 1, mitochondrial [KO:K01679] [EC:4.2.1.2]
            11436578  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            11430390  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            25484448  malate dehydrogenase [KO:K00025] [EC:1.1.1.37]
            25502524  malate dehydrogenase, mitochondrial [KO:K00026] [EC:1.1.1.37]
            11405683  malate dehydrogenase 2, peroxisomal [KO:K00026] [EC:1.1.1.37]
            11420535  malate dehydrogenase, glyoxysomal [KO:K00026] [EC:1.1.1.37]
            120580136  malate dehydrogenase, chloroplastic [KO:K00026] [EC:1.1.1.37]
            25501396  phosphoenolpyruvate carboxykinase (ATP) 1 [KO:K01610] [EC:4.1.1.49]
            11433679  phosphoenolpyruvate carboxykinase (ATP) 1 [KO:K01610] [EC:4.1.1.49]
            25495006  phosphoenolpyruvate carboxykinase (ATP) 1 [KO:K01610] [EC:4.1.1.49]
            11416624  pyruvate dehydrogenase E1 component subunit alpha, mitochondrial [KO:K00161] [EC:1.2.4.1]
            25500614  pyruvate dehydrogenase E1 component subunit alpha-3, chloroplastic [KO:K00161] [EC:1.2.4.1]
            11414398  pyruvate dehydrogenase E1 component subunit alpha, mitochondrial [KO:K00161] [EC:1.2.4.1]
            11411402  pyruvate dehydrogenase E1 component subunit beta-3, chloroplastic [KO:K00162] [EC:1.2.4.1]
            120577439  pyruvate dehydrogenase E1 component subunit beta-3, chloroplastic-like [KO:K00162] [EC:1.2.4.1]
            11442185  pyruvate dehydrogenase E1 component subunit beta, mitochondrial [KO:K00162] [EC:1.2.4.1]
            11423972  dihydrolipoyllysine-residue acetyltransferase component 2 of pyruvate dehydrogenase complex, mitochondrial [KO:K00627] [EC:2.3.1.12]
            25484885  dihydrolipoyllysine-residue acetyltransferase component 1 of pyruvate dehydrogenase complex, mitochondrial [KO:K00627] [EC:2.3.1.12]
            25484957  dihydrolipoyllysine-residue acetyltransferase component 5 of pyruvate dehydrogenase complex, chloroplastic [KO:K00627] [EC:2.3.1.12]
            25485515  dihydrolipoyllysine-residue acetyltransferase component 4 of pyruvate dehydrogenase complex, chloroplastic [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 mtr00010  Glycolysis / Gluconeogenesis
            mtr00053  Ascorbate and aldarate metabolism
            mtr00061  Fatty acid biosynthesis
            mtr00062  Fatty acid elongation
            mtr00071  Fatty acid degradation
            mtr00190  Oxidative phosphorylation
            mtr00220  Arginine biosynthesis
            mtr00250  Alanine, aspartate and glutamate metabolism
            mtr00280  Valine, leucine and isoleucine degradation
            mtr00350  Tyrosine metabolism
            mtr00470  D-Amino acid metabolism
            mtr00630  Glyoxylate and dicarboxylate metabolism
KO_PATHWAY  ko00020
///
