PATHWAY: ebe00020 Help
Entry
Name
Citrate cycle (TCA cycle) - Escherichia coli BL21(DE3)
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
Ortholog table
Module
ebe_M00010 Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:ebe00020 ]
ebe_M00011 Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:ebe00020 ]
Other DBs
Organism
Escherichia coli BL21(DE3) [GN:
ebe ]
Gene
B21_00674 sucA; E1(0) component of 2-oxoglutarate dehydrogenase, subunit of 2-oxoglutarate decarboxylase, thiamin-requiring and 2-oxoglutarate dehydrogenase complex [KO:K00164 ] [EC:1.2.4.2 ]
B21_00675 sucB; sucB, subunit of dihydrolipoyltranssuccinylase and 2-oxoglutarate dehydrogenase complex [KO:K00658 ] [EC:2.3.1.61 ]
B21_00114 lpd; E3 monomer, subunit of lipoamide dehydrogenase, pyruvate dehydrogenase multienzyme complex, glycine cleavage system and 2-oxoglutarate dehydrogenase complex [KO:K00382 ] [EC:1.8.1.4 ]
B21_00677 sucD; succinyl-CoA synthetase, alpha subunit, subunit of succinyl-CoA synthetase [KO:K01902 ] [EC:6.2.1.5 ]
B21_00676 sucC; succinyl-CoA synthetase, beta subunit, subunit of succinyl-CoA synthetase [KO:K01903 ] [EC:6.2.1.5 ]
B21_00672 sdhA; succinate dehydrogenase flavoprotein, subunit of succinate dehydrogenase [KO:K00239 ] [EC:1.3.5.1 ]
B21_00673 sdhB; succinate dehydrogenase iron-sulfur protein, subunit of succinate dehydrogenase [KO:K00240 ] [EC:1.3.5.1 ]
B21_00670 sdhC; succinate dehydrogenase membrane protein, subunit of succinate dehydrogenase [KO:K00241 ]
B21_00671 sdhD; succinate dehydrogenase membrane protein, subunit of succinate dehydrogenase [KO:K00242 ]
B21_03987 frdB; fumarate reductase iron-sulfur protein, subunit of fumarate reductase [KO:K00245 ] [EC:1.3.5.1 ]
B21_03986 frdC; fumarate reductase membrane protein, subunit of fumarate reductase [KO:K00246 ]
B21_03985 frdD; fumarate reductase membrane protein, subunit of fumarate reductase [KO:K00247 ]
B21_00112 aceE; E1p component of pyruvate dehydrogenase complex, subunit of pyruvate dehydrogenase and pyruvate dehydrogenase multienzyme complex [KO:K00163 ] [EC:1.2.4.1 ]
B21_00113 aceF; dihydrolipoamide acetyltransferase / lipoate acetyltransferase, subunit of pyruvate dehydrogenase multienzyme complex [KO:K00627 ] [EC:2.3.1.12 ]
Compound
C05125 2-(alpha-Hydroxyethyl)thiamine diphosphate
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
ebe00053 Ascorbate and aldarate metabolism
ebe00250 Alanine, aspartate and glutamate metabolism
ebe00280 Valine, leucine and isoleucine degradation
ebe00630 Glyoxylate and dicarboxylate metabolism
KO pathway
LinkDB
All DBs