This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Synonyms: 2-oxoglutarate dehydrogenase complex, 2-ketoglutarate dehydrogenase complex
|Superclasses:||Generation of Precursor Metabolites and Energy → Respiration|
Some taxa known to possess this pathway include : Bacillus subtilis, Deinococcus radiodurans, Escherichia coli K-12 substr. MG1655, Geobacillus stearothermophilus, Homo sapiens, Mus musculus, Pseudomonas aeruginosa, Pseudomonas putida, Rattus norvegicus, Sulfolobus solfataricus, Synechocystis
2-oxo acid dehydrogenase complexes convert 2-oxo acids to the corresponding acyl-CoA derivatives and produce NADH and CO2 in an irreversible reaction. Five members of this family are known at present, including the pyruvate dehydrogenase complex (PDHC), the 2-oxoglutarate dehydrogenase complex (OGDHC - this pathway), the branched-chain α-keto acid dehydrogenase complex (BCDHC), the glycine cleavage complex (GDHC), and the acetoin dehydrogenase complex (ADHC). They all function at strategic points in (usually aerobic) catabolic pathways and are subject to stringent control [deKok98].
With the exception of GDHC, the 2-oxo acid dehydrogenase complexes share a common structure. They consist of three main components, namely a 2-oxo acid dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2), and dihydrolipoamide dehydrogenase (E3). In Gram-positive bacteria and mitochondria, the E1 component is a heterodimer composed of two subunits, while in Gram-negative bacteria it is made of a single type of subunit.
In all cases described so far, many copies of each subunit assemble to form the full complex. For example, the Escherichia coli K-12 pyruvate dehydrogenase comprises 24, 24, and 12 units of the E1, E2, and E3 components, respectively. The core of the complex is made of either 24 (Gram-negative bacteria) or 60 (mitochondria) E2 units, which contain the lipoyl active site in the form of lipoyllysine, as well as binding sites for the other two subunits. E1, which contains a thiamine diphosphate cofactor, catalyzes the binding of the 2-oxo acid to the lipoyl group of E2, which then transfers an acyl group (the nature of the acyl group depends on the particular enzyme) to coenzyme A, forming an acyl-CoA. During this transfer, the lipoyl group is reduced to dihydrolipoyl. E3 then transfers the protons to NAD, forming NADH and restoring the dihydrolipoyllysine group back to lipoyllysine.
Cryoelectron microscopy of PDHC from Geobacillus stearothermophilus [Milne02] and ox kidney [Zhou01] has revealed that the E2 inner core is surrounded by an outer shell of E1 and E3 components, with the lipoyl domains confined to the annular space between them where they must make successive journeys between the three types of active sites (E1-E3), which are physically far apart [Fries03].
About This Pathway
The pathway illustrated here presents the reactions catalyzed by the 2-oxoglutarate dehydrogenase complex, a key enzyme of the TCA cycle I (prokaryotic). These reactions can be summarized by the general reaction
which is the form commonly found in the TCA cycle.
Unification Links: EcoCyc:PWY-5084
Fries03: Fries M, Jung HI, Perham RN (2003). "Reaction mechanism of the heterotetrameric (alpha2beta2) E1 component of 2-oxo acid dehydrogenase multienzyme complexes." Biochemistry 42(23);6996-7002. PMID: 12795594
Milne02: Milne JL, Shi D, Rosenthal PB, Sunshine JS, Domingo GJ, Wu X, Brooks BR, Perham RN, Henderson R, Subramaniam S (2002). "Molecular architecture and mechanism of an icosahedral pyruvate dehydrogenase complex: a multifunctional catalytic machine." EMBO J 21(21);5587-98. PMID: 12411477
Zhou01: Zhou ZH, McCarthy DB, O'Connor CM, Reed LJ, Stoops JK (2001). "The remarkable structural and functional organization of the eukaryotic pyruvate dehydrogenase complexes." Proc Natl Acad Sci U S A 98(26);14802-7. PMID: 11752427
Ali94: Ali G, Wasco W, Cai X, Szabo P, Sheu KF, Cooper AJ, Gaston SM, Gusella JF, Tanzi RE, Blass JP (1994). "Isolation, characterization, and mapping of gene encoding dihydrolipoyl succinyltransferase (E2k) of human alpha-ketoglutarate dehydrogenase complex." Somat Cell Mol Genet 20(2);99-105. PMID: 8009371
Arifuzzaman06: Arifuzzaman M, Maeda M, Itoh A, Nishikata K, Takita C, Saito R, Ara T, Nakahigashi K, Huang HC, Hirai A, Tsuzuki K, Nakamura S, Altaf-Ul-Amin M, Oshima T, Baba T, Yamamoto N, Kawamura T, Ioka-Nakamichi T, Kitagawa M, Tomita M, Kanaya S, Wada C, Mori H (2006). "Large-scale identification of protein-protein interaction of Escherichia coli K-12." Genome Res 16(5);686-91. PMID: 16606699
Bryk02: Bryk R, Lima CD, Erdjument-Bromage H, Tempst P, Nathan C (2002). "Metabolic enzymes of mycobacteria linked to antioxidant defense by a thioredoxin-like protein." Science 295(5557);1073-7. PMID: 11799204
Bunik08: Bunik VI, Degtyarev D (2008). "Structure-function relationships in the 2-oxo acid dehydrogenase family: substrate-specific signatures and functional predictions for the 2-oxoglutarate dehydrogenase-like proteins." Proteins 71(2);874-90. PMID: 18004749
Butland05: Butland G, Peregrin-Alvarez JM, Li J, Yang W, Yang X, Canadien V, Starostine A, Richards D, Beattie B, Krogan N, Davey M, Parkinson J, Greenblatt J, Emili A (2005). "Interaction network containing conserved and essential protein complexes in Escherichia coli." Nature 433(7025);531-7. PMID: 15690043
Carothers89: Carothers DJ, Pons G, Patel MS (1989). "Dihydrolipoamide dehydrogenase: functional similarities and divergent evolution of the pyridine nucleotide-disulfide oxidoreductases." Arch Biochem Biophys 1989;268(2);409-25. PMID: 2643922
Coggins76: Coggins JR, Hooper EA, Perham RN (1976). "Use of dimethyl suberimidate and novel periodate-cleavable bis(imido esters) to study the quaternary structure of the pyruvate dehydrogenase multienzyme complex of Escherichia coli." Biochemistry 15(12);2527-33. PMID: 779824
Darlison84: Darlison MG, Spencer ME, Guest JR (1984). "Nucleotide sequence of the sucA gene encoding the 2-oxoglutarate dehydrogenase of Escherichia coli K-12." Eur J Biochem. 141(2):351-9. PMID: 6376123
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Feeney11: Feeney MA, Veeravalli K, Boyd D, Gon S, Faulkner MJ, Georgiou G, Beckwith J (2011). "Repurposing lipoic acid changes electron flow in two important metabolic pathways of Escherichia coli." Proc Natl Acad Sci U S A 108(19);7991-6. PMID: 21521794
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