Entry
Name
Citrate cycle (TCA cycle) - Klebsiella pneumoniae subsp. rhinoscleromatis SB3432
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
kpr_M00010 Citrate cycle, first carbon oxidation, oxaloacetate => 2-oxoglutarate [PATH:kpr00020 ]
kpr_M00011 Citrate cycle, second carbon oxidation, 2-oxoglutarate => oxaloacetate [PATH:kpr00020 ]
Other DBs
Organism
Klebsiella pneumoniae subsp. rhinoscleromatis SB3432 [GN:
kpr ]
Gene
KPR_3851 cisY; highly similar to citrate synthase from Salmonella typhimurium (sp [KO:K01647 ] [EC:2.3.3.1 ]
KPR_4079 unnamed protein product; similar to citrate synthase from Escherichia coli O150:H5 strain SE15 (tr [KO:K01647 ] [EC:2.3.3.1 ]
KPR_2324 acnA; highly similar to aconitate hydratase 1 from Escherichia coli strain K12 (sp [KO:K01681 ] [EC:4.2.1.3 ]
KPR_2189 icdA; hihly similar to isocitrate dehydrogenase [NADP] from Escherichia coli O6 (tr [KO:K00031 ] [EC:1.1.1.42 ]
KPR_3846 sucA; highly similar to 2-oxoglutarate dehydrogenase decarboxylase component from Escherichia coli strain UTI89 - UPEC (tr [KO:K00164 ] [EC:1.2.4.2 ]
KPR_3845 sucB; highly similar to dihydrolipoyllysine-residue succinyltransferase, E2 component of oxoglutarate dehydrogenase (succinyl-transferring) complex from Escherichia coli O55:H7 strain CB9615 - EPEC (tr [KO:K00658 ] [EC:2.3.1.61 ]
KPR_1049 lpdA; highly similar to dihydrolipoyl dehydrogenase from Escherichia coli strain UTI89 - UPEC (tr [KO:K00382 ] [EC:1.8.1.4 ]
KPR_3843 sucD; highly similar to succinyl-CoA ligase [ADP-forming] subunit alpha from Escherichia coli strain UTI89 - UPEC (tr [KO:K01902 ] [EC:6.2.1.5 ]
KPR_3844 sucC; highly similar to succinyl-CoA ligase [ADP-forming] subunit beta from Klebsiella pneumoniae subsp. pneumoniae strain ATCC 700721 - MGH 78578 (sp [KO:K01903 ] [EC:6.2.1.5 ]
KPR_3848 sdhA; highly similar to succinate dehydrogenase flavoprotein subunit from Escherichia coli strain UTI89 - UPEC (tr [KO:K00239 ] [EC:1.3.5.1 ]
KPR_3847 sdhB; highly similar to succinate dehydrogenase from Escherichia coli O157:H7 (tr [KO:K00240 ] [EC:1.3.5.1 ]
KPR_3850 sdhC; highly similar to succinate dehydrogenase, cytochrome b556 subunit from Escherichia coli strain ATCC 33849 - DSM 4235 - NCIB 12045 - K12 - DH1 (tr [KO:K00241 ]
KPR_3849 sdhD; highly similar to succinate dehydrogenase hydrophobic subunit from Escherichia coli strain UTI89 - UPEC (tr [KO:K00242 ]
KPR_0532 frdA; highly similar to putative fumarate reductase (anaerobic) catalytic and NAD-flavoprotein subunit from Escherichia coli O7:K1 strain IAI39 - ExPEC (tr [KO:K00244 ] [EC:1.3.5.1 ]
KPR_0531 frdB; highly similar to putative fumarate reductase, iron-sulfur protein from Salmonella enterica (tr [KO:K00245 ] [EC:1.3.5.1 ]
KPR_0530 frdC; highly similar to fumarate reductase 15 kDa hydrophobic protein from Klebsiella pneumoniae strain 342 (sp [KO:K00246 ]
KPR_0529 frdD; highly similar to fumarate reductase 13 kDa hydrophobic protein from Klebsiella pneumoniae strain 342 (sp [KO:K00247 ]
KPR_2765 unnamed protein product; highly similar to C-terminal region of fumarase from Enterobacter cloacae (tr [KO:K01676 ] [EC:4.2.1.2 ]
KPR_2827 fumB; highly similar to anaerobic class I fumarate hydratase (fumaraseB) from Escherichia coli O127:H6 strain E2348-69 - EPEC (tr [KO:K01676 ] [EC:4.2.1.2 ]
KPR_2826 fumC; highly similar to fumarate hydratase class II from Salmonella typhi (sp [KO:K01679 ] [EC:4.2.1.2 ]
KPR_2677 ydhZ; highly similar to putative uncharacterized protein YdhZ from Escherichia coli strain UTI89 - UPEC (tr [KO:K01675 ] [EC:4.2.1.2 ]
KPR_4827 mdh; highly similar to malate dehydrogenase from Klebsiella pneumoniae subsp. pneumoniae strain ATCC 700721 - MGH 78578 (sp [KO:K00024 ] [EC:1.1.1.37 ]
KPR_2084 mqo; highly similar to probable malate:quinone oxidoreductase from Escherichia fergusonii strain ATCC 35469 - DSM 13698 - CDC 0568-73 (sp [KO:K00116 ] [EC:1.1.5.4 ]
KPR_2755 mqo; highly similar to probable malate:quinone oxidoreductase from Enterobacter sakazakii (sp [KO:K00116 ] [EC:1.1.5.4 ]
KPR_3194 pckA; highly similar to phosphoenolpyruvate carboxykinase [ATP] from Shigella sonnei (sp [KO:K01610 ] [EC:4.1.1.49 ]
KPR_0695 pckA; highly similar to phosphoenolpyruvate carboxykinase [ATP] from Salmonella typhi (sp [KO:K01610 ] [EC:4.1.1.49 ]
KPR_1047 aceE; highly similar to pyruvate dehydrogenase E1 component from Escherichia coli O55:H7 strain CB9615 - EPEC (tr [KO:K00163 ] [EC:1.2.4.1 ]
KPR_1048 aceF; highly similar to dihydrolipoyllysine-residue acetyltransferase from Salmonella enterica (tr [KO:K00627 ] [EC:2.3.1.12 ]
KPR_2889 unnamed protein product; highly similar to probable pyruvate-flavodoxin oxidoreductase from Escherichia coli O44:H18 strain 042 - EAEC (tr [KO:K03737 ] [EC:1.2.7.1 1.2.7.-]
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
kpr00053 Ascorbate and aldarate metabolism
kpr00250 Alanine, aspartate and glutamate metabolism
kpr00280 Valine, leucine and isoleucine degradation
kpr00630 Glyoxylate and dicarboxylate metabolism
KO pathway
LinkDB
All DBs