ENTRY       zma00020                    Pathway
NAME        Citrate cycle (TCA cycle) - Zea mays (maize)
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 zma00020  Citrate cycle (TCA cycle)
MODULE      zma_M00003  Gluconeogenesis, oxaloacetate => fructose-6P [PATH:zma00020]
            zma_M00009  Citrate cycle (TCA cycle, Krebs cycle) [PATH:zma00020]
            zma_M00010  Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:zma00020]
            zma_M00011  Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:zma00020]
            zma_M00307  Pyruvate oxidation, pyruvate => acetyl-CoA [PATH:zma00020]
DBLINKS     GO: 0006099
ORGANISM    Zea mays (maize) [GN:zma]
GENE        100194338  uncharacterized protein LOC100194338 [KO:K01647] [EC:2.3.3.1]
            100280203  uncharacterized protein LOC100280203 isoform 1 [KO:K01647] [EC:2.3.3.1]
            100279573  uncharacterized protein LOC100279573 [KO:K01647] [EC:2.3.3.1]
            100275174  uncharacterized protein LOC100275174 [KO:K01647] [EC:2.3.3.1]
            100273868  uncharacterized protein LOC100273868 [KO:K01648] [EC:2.3.3.8]
            100282948  uncharacterized protein LOC100282948 [KO:K01648] [EC:2.3.3.8]
            100381760  uncharacterized protein LOC100381760 [KO:K01648] [EC:2.3.3.8]
            103635086  ATP-citrate synthase beta chain protein 1 [KO:K01648] [EC:2.3.3.8]
            100304315  uncharacterized protein LOC100304315 [KO:K01681] [EC:4.2.1.3]
            100281040  aconitase 2 isoform 1 [KO:K01681] [EC:4.2.1.3]
            100216599  uncharacterized protein LOC100216599 [KO:K01681] [EC:4.2.1.3]
            103646899  putative aconitate hydratase, cytoplasmic isoform X1 [KO:K01681] [EC:4.2.1.3]
            103647708  putative aconitate hydratase, cytoplasmic isoform X1 [KO:K01681] [EC:4.2.1.3]
            100304277  uncharacterized protein LOC100304277 [KO:K01681] [EC:4.2.1.3]
            100191657  uncharacterized protein LOC100191657 [KO:K00031] [EC:1.1.1.42]
            100272371  uncharacterized protein LOC100272371 [KO:K00031] [EC:1.1.1.42]
            100217128  seed maturation protein PM41 [KO:K00031] [EC:1.1.1.42]
            100274592  uncharacterized protein LOC100274592 [KO:K00031] [EC:1.1.1.42]
            103633296  uncharacterized protein LOC103633296 isoform X2 [KO:K00031] [EC:1.1.1.42]
            100191841  uncharacterized protein LOC100191841 [KO:K00030] [EC:1.1.1.41]
            100283574  3-isopropylmalate dehydrogenase [KO:K00030] [EC:1.1.1.41]
            100272953  uncharacterized protein LOC100272953 [KO:K00030] [EC:1.1.1.41]
            100274026  uncharacterized protein LOC100274026 [KO:K00030] [EC:1.1.1.41]
            542698  isocitrate dehydrogenase [NAD] regulatory subunit 1, mitochondrial isoform 1 [KO:K00030] [EC:1.1.1.41]
            100383412  uncharacterized protein LOC100383412 [KO:K00164] [EC:1.2.4.2]
            100383579  2-oxoglutarate dehydrogenase E1 component [KO:K00164] [EC:1.2.4.2]
            100383847  uncharacterized protein LOC100383847 [KO:K00164] [EC:1.2.4.2]
            100280624  dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex [KO:K00658] [EC:2.3.1.61]
            100284269  dihydrolipoyllysine-residue succinyltransferase component of 2-oxoglutarate dehydrogenase complex [KO:K00658] [EC:2.3.1.61]
            100501719  uncharacterized protein LOC100501719 isoform 1 [KO:K00382] [EC:1.8.1.4]
            100381818  uncharacterized protein LOC100381818 [KO:K00382] [EC:1.8.1.4]
            100383599  uncharacterized protein LOC100383599 [KO:K00382] [EC:1.8.1.4]
            103650140  dihydrolipoyl dehydrogenase 1, mitochondrial [KO:K00382] [EC:1.8.1.4]
            100216609  succinyl-CoA ligase alpha-chain 2 [KO:K01899] [EC:6.2.1.4 6.2.1.5]
            100283329  succinyl-CoA ligase alpha-chain 2 [KO:K01899] [EC:6.2.1.4 6.2.1.5]
            100284286  succinyl-CoA ligase beta-chain [KO:K01900] [EC:6.2.1.4 6.2.1.5]
            100284826  succinyl-CoA ligase beta-chain [KO:K01900] [EC:6.2.1.4 6.2.1.5]
            100279930  uncharacterized protein LOC100279930 [KO:K00234] [EC:1.3.5.1]
            100280324  uncharacterized protein LOC100280324 [KO:K00234] [EC:1.3.5.1]
            100216648  uncharacterized protein LOC100216648 [KO:K00235] [EC:1.3.5.1]
            100502233  ribosomal protein S14-like [KO:K00235] [EC:1.3.5.1]
            103653238  succinate dehydrogenase [ubiquinone] iron-sulfur subunit 1, mitochondrial [KO:K00235] [EC:1.3.5.1]
            109944584  succinate dehydrogenase [ubiquinone] iron-sulfur subunit 2, mitochondrial [KO:K00235] [EC:1.3.5.1]
            115874042  Succinate dehydrogenase [ubiquinone] iron-sulfur subunit 1, mitochondrial-like [KO:K00235] [EC:1.3.5.1]
            100281355  uncharacterized protein LOC100281355 [KO:K00236]
            100283351  succinate dehydrogenase subunit 3 [KO:K00236]
            100277027  uncharacterized protein LOC100277027 [KO:K25801]
            100274754  uncharacterized protein LOC100274754 [KO:K25801]
            100279871  uncharacterized protein LOC100279871 [KO:K01679] [EC:4.2.1.2]
            103648465  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            542598  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            100280767  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            103633793  malate dehydrogenase, cytoplasmic [KO:K00025] [EC:1.1.1.37]
            100274264  malate dehydrogenase 2 [KO:K00026] [EC:1.1.1.37]
            100273428  uncharacterized protein LOC100273428 [KO:K00026] [EC:1.1.1.37]
            100272900  uncharacterized protein LOC100272900 [KO:K00026] [EC:1.1.1.37]
            100193491  uncharacterized protein LOC100193491 [KO:K00026] [EC:1.1.1.37]
            100193663  malate dehydrogenase [KO:K00026] [EC:1.1.1.37]
            100282134  malate dehydrogenase, glyoxysomal [KO:K00026] [EC:1.1.1.37]
            100193743  Malate dehydrogenase [KO:K00026] [EC:1.1.1.37]
            107305678  uncharacterized protein LOC107305678 [KO:K00026] [EC:1.1.1.37]
            541622  phosphoenolpyruvate carboxykinase (ATP) isoform 1 [KO:K01610] [EC:4.1.1.49]
            100279748  phosphoenolpyruvate carboxykinase homolog 2 [KO:K01610] [EC:4.1.1.49]
            100272834  uncharacterized protein LOC100272834 [KO:K00161] [EC:1.2.4.1]
            100272256  uncharacterized protein LOC100272256 [KO:K00161] [EC:1.2.4.1]
            732791  pyruvate dehydrogenase 1 [KO:K00161] [EC:1.2.4.1]
            100283889  pyruvate dehydrogenase E1 component alpha subunit [KO:K00161] [EC:1.2.4.1]
            541705  pyruvate dehydrogenase 2 [KO:K00162] [EC:1.2.4.1]
            542607  pyruvate dehydrogenase E1 beta subunit [KO:K00162] [EC:1.2.4.1]
            542483  pyruvate dehydrogenase E1 beta subunit [KO:K00162] [EC:1.2.4.1]
            100282233  uncharacterized protein LOC100282233 [KO:K00162] [EC:1.2.4.1]
            100284103  pyruvate dehydrogenase E1 component subunit beta [KO:K00162] [EC:1.2.4.1]
            100192900  uncharacterized protein LOC100192900 [KO:K00627] [EC:2.3.1.12]
            541781  dihydrolipoamide S-acetyltransferase [KO:K00627] [EC:2.3.1.12]
            100274483  dihydrolipoyllysine-residue acetyltransferase component of pyruvatedehydrogenase complex [KO:K00627] [EC:2.3.1.12]
            100279373  uncharacterized protein LOC100279373 [KO:K00627] [EC:2.3.1.12]
            100284493  dihydrolipoamide S-acetyltransferase 1 [KO:K00627] [EC:2.3.1.12]
            100285796  dihydrolipoyllysine-residue acetyltransferase component of pyruvatedehydrogenase complex [KO:K00627] [EC:2.3.1.12]
            103644210  dihydrolipoyllysine-residue acetyltransferase component 1 of pyruvate dehydrogenase complex, mitochondrial [KO:K00627] [EC:2.3.1.12]
            100272519  uncharacterized protein LOC100272519 [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 zma00010  Glycolysis / Gluconeogenesis
            zma00053  Ascorbate and aldarate metabolism
            zma00061  Fatty acid biosynthesis
            zma00062  Fatty acid elongation
            zma00071  Fatty acid degradation
            zma00190  Oxidative phosphorylation
            zma00220  Arginine biosynthesis
            zma00250  Alanine, aspartate and glutamate metabolism
            zma00280  Valine, leucine and isoleucine degradation
            zma00350  Tyrosine metabolism
            zma00470  D-Amino acid metabolism
            zma00630  Glyoxylate and dicarboxylate metabolism
KO_PATHWAY  ko00020
///
