GDP + Orthophosphate + Succinyl-CoA <=> GTP + Succinate + CoA

Stable Identifier
Reaction [transition]
Homo sapiens
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Mitochondrial succinate CoA ligase (ADP-forming) catalyzes the reversible conversion of succinyl CoA to succinate plus Coenzyme A, coupled to the conversion of ADP and orthophosphate to ATP. The enzyme is a heterodimer containing SUCLG1 and SUCLA2 monomers.

The enzyme catalyzing the reaction in vertebrates is a heterodimer that occurs in two isoforms. The enzymes have been purified from pigeon and rat tissue and characterized in detail. Both isoforms, an alpha:betaA heterodimer and an alpha:betaG heterodimer, catalyze the reversible conversion of succinyl CoA to succinate plus Coenzyme A. The alpha:betaA heterodimer couples this conversion to the synthesis of ATP from ADP and orthophosphate, while the alpha:betaG heterodimer couples it to the synthesis of GTP from GDP and orthophosphate (Johnson et al. 1998a,b; Lambeth et al. 2004). Consistent with these results in model systems, patients homozygous for a mutant allele of the gene encoding the ADP enzyme beta subunit, SUCLA2, are deficient in succinyl CoA ligase activity (Elpeleg et al. 2005).

Both isoforms are found in vivo, and appear to be expressed at different levels in various tissues. Their relative contributions to the flux of carbon atoms through the TCA cycle are unknown. Genetic and biochemical data suggest that the alpha:betaA isoform may be required to catalyze the reverse reaction, conversion of succinate, Coenzyme A, and ATP to succinyl CoA, ADP, and orthophosphate for heme biosynthesis (Furuyama and Sassa 2000).

Literature References
PubMed ID Title Journal Year
13181903 Guanosine triphosphate, the primary product of phosphorylation coupled to the breakdown of succinyl coenzyme A

Sanadi, DR, Ayengar, P, Gibson, M

Biochim Biophys Acta 1954
10727444 Interaction between succinyl CoA synthetase and the heme-biosynthetic enzyme ALAS-E is disrupted in sideroblastic anemia

Sassa, S, Furuyama, K

J Clin Invest 2000
17668387 Deficiency of the alpha subunit of succinate-coenzyme A ligase causes fatal infantile lactic acidosis with mitochondrial DNA depletion

Kristensen, E, Duno, M, Mogensen, B, Wibrand, F, Ostergaard, E, Shoubridge, EA, Christensen, E

Am J Hum Genet 2007
9765291 Genetic evidence for the expression of ATP- and GTP-specific succinyl-CoA synthetases in multicellular eucaryotes

Mehus, JG, Lambeth, DO, Milavetz, BI, Tews, KN, Johnson, JD

J Biol Chem 1998
15234968 Expression of two succinyl-CoA synthetases with different nucleotide specificities in mammalian tissues

Lambeth, DO, Frohlich, D, Milavetz, BI, Adkins, S, Tews, KN

J Biol Chem 2004
9765290 Characterization of the ATP- and GTP-specific succinyl-CoA synthetases in pigeon. The enzymes incorporate the same alpha-subunit.

Lambeth, DO, Muhonen, WW, Johnson, JD

J Biol Chem 1998
Catalyst Activity

succinate-CoA ligase (GDP-forming) activity of SUCLG1:SUCLG2 [mitochondrial matrix]

Orthologous Events
Cross References
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