GO:0120551 2-oxoglutarate decarboxylation to succinyl-CoA: TCA Cycle Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0120551 describes the three-step conversion of 2-oxoglutarate (alpha-ketoglutarate) plus coenzyme A and NAD+ into succinyl-CoA, CO2, and NADH, catalyzed by the multienzyme 2-oxoglutarate dehydrogenase complex (OGDHC).
• The eukaryotic OGDHC is a large multienzyme assembly whose core is formed by dihydrolipoamide succinyltransferase (DLST), with 2-oxoglutarate dehydrogenase (OGDH) and dihydrolipoamide dehydrogenase (DLD) as peripheral subunits; MRPS36 was recently identified as a structural link in the complex.
• The mitochondrial 2-oxoadipate dehydrogenase complex shares its E2 (DLST) and E3 (DLD) components with OGDHC, and both complexes can generate reactive oxygen species.
• Biallelic variants in MRPS36 cause a new form of Leigh syndrome, directly linking this GO term to human mitochondrial disease.
• The reaction is central to the TCA cycle, glutamate catabolism, and amino acid oxidation, and is conserved from bacteria and archaea to humans.
• Enzyme-coupled assays that detect succinate or succinyl-CoA formation are widely used to measure 2-oxoglutarate-dependent activities in vitro.
Description
GO:0120551, 2-oxoglutarate decarboxylation to succinyl-CoA, is a biological process that converts 2-oxoglutarate (also called alpha-ketoglutarate) into succinyl-CoA, with concomitant release of CO2 and reduction of NAD+ to NADH. In most organisms this pathway is a core segment of the tricarboxylic acid (TCA) cycle, and it is carried out by a large multienzyme assembly known as the 2-oxoglutarate dehydrogenase complex (OGDHC). The overall stoichiometry is 2-oxoglutarate + coenzyme A + NAD+ -> succinyl-CoA + CO2 + NADH, and the process is often referred to by synonyms such as the 2-oxoglutarate dehydrogenase system or the 2-ketoglutarate dehydrogenase system. Because it sits at the intersection of carbon and nitrogen metabolism, this reaction is essential for mitochondrial energy production, glutamate catabolism, and amino acid oxidation. Researchers study GO:0120551 to understand mitochondrial bioenergetics, reactive oxygen species (ROS) production, and inherited metabolic disorders. The recent identification of MRPS36 as a structural component of the eukaryotic OGDHC has renewed interest in the assembly and regulation of this complex. This article summarizes the definition, mechanism, key genes, disease links, and experimental methods relevant to GO:0120551, with all factual statements supported by the verified literature listed below.
2-oxoglutarate decarboxylation to succinyl-CoA At A Glance
| GO ID | GO:0120551 |
|---|---|
| GO term | 2-oxoglutarate decarboxylation to succinyl-CoA |
| Ontology | biological_process |
| Synonym | 2alpha-ketoglutarate dehydrogenase system; 2-ketoglutarate dehydrogenase system; 2-oxoglutarate dehydrogenase system |
| Major function | Oxidative decarboxylation of 2-oxoglutarate to succinyl-CoA within the TCA cycle, generating NADH and CO2 |
| Enzyme complex | 2-oxoglutarate dehydrogenase complex (OGDHC), a multienzyme assembly |
| Key subunits | OGDH (E1), DLST (E2), DLD (E3), and MRPS36 as a structural link in eukaryotes |
| Related pathway | TCA cycle; also linked to 2-oxoadipate dehydrogenase complex via shared E2/E3 components |
| Disease relevance | Biallelic MRPS36 variants cause a new form of Leigh syndrome |
What Is GO:0120551?
GO:0120551 is defined as the chemical reactions and pathways resulting in the formation of succinyl-CoA from 2-oxoglutarate. In most organisms, this pathway is part of the TCA cycle and comprises a series of three reactions carried out by a multisubunit complex called the 2-oxoglutarate dehydrogenase complex, even though 2-oxoglutarate dehydrogenase activity describes only one of those reactions. The combination of the three reactions can be summarized as: 2-oxoglutarate + coenzyme A + NAD+ -> succinyl-CoA + CO2 + NADH.
Why Is 2-oxoglutarate decarboxylation to succinyl-CoA Important in Cell Biology?
GO:0120551 is important because it represents a central step in the TCA cycle and mitochondrial oxidative metabolism, converting 2-oxoglutarate to succinyl-CoA while producing NADH and CO2. This reaction links carbon flux from glutamate and other amino acids into the TCA cycle, and it is conserved across bacteria, archaea, and eukaryotes. The 2-oxoglutarate dehydrogenase complex is also a source of mitochondrial reactive oxygen species, and it shares components with the 2-oxoadipate dehydrogenase complex, connecting this process to redox biology and lysine metabolism. Clinically, disruption of the complex is associated with severe mitochondrial disease, as shown by biallelic MRPS36 variants causing Leigh syndrome. Therefore, understanding GO:0120551 is essential for researchers studying mitochondrial bioenergetics, metabolic disorders, and the assembly of multienzyme complexes.
• Central TCA cycle step: converts 2-oxoglutarate to succinyl-CoA, feeding reducing equivalents into the respiratory chain.
• Links glutamate catabolism and amino acid oxidation to mitochondrial energy production.
• The OGDHC is a major site of mitochondrial reactive oxygen species generation.
• Shares E2 and E3 components with the 2-oxoadipate dehydrogenase complex, integrating lysine and 2-oxoadipate metabolism.
• Mutations in OGDHC components, including MRPS36, cause Leigh syndrome and related mitochondrial disorders.
• Conserved across hyperthermophilic archaea, bacteria, and eukaryotes, making it a model for enzyme evolution.
• Target for metabolic engineering, e.g., improving poly-gamma-glutamic acid production by deleting glutamate metabolism genes.
• Enzyme-coupled assays for succinate/succinyl-CoA formation enable high-throughput screening of 2-oxoglutarate-dependent enzymes.
What Happens During 2-oxoglutarate decarboxylation to succinyl-CoA?
Step 1: Oxidative decarboxylation of 2-oxoglutarate by the E1 subunit (OGDH)
In simple terms: The first step removes a carbon from 2-oxoglutarate as CO2 and transfers the remaining succinyl group to the enzyme complex.
The E1 component, 2-oxoglutarate dehydrogenase (OGDH), catalyzes the oxidative decarboxylation of 2-oxoglutarate, releasing CO2 and forming a succinyl-enzyme intermediate. This step requires thiamine pyrophosphate (TPP) as a cofactor and is the rate-limiting reaction of the complex. The overall process is part of the TCA cycle and is conserved in most organisms.
Step 2: Transfer of the succinyl group to coenzyme A by the E2 subunit (DLST)
In simple terms: The second step attaches the succinyl group to coenzyme A, producing succinyl-CoA.
The E2 component, dihydrolipoamide succinyltransferase (DLST), forms the core of the 2-oxoglutarate dehydrogenase complex and catalyzes the transfer of the succinyl moiety to coenzyme A, generating succinyl-CoA. DLST also accepts electrons via lipoamide and passes them to the E3 subunit. In eukaryotes, MRPS36 provides a structural link that helps organize the complex.
Step 3: Regeneration of oxidized lipoamide by the E3 subunit (DLD)
In simple terms: The third step recycles the enzyme so it can start another round, using NAD+ to accept electrons.
The E3 component, dihydrolipoamide dehydrogenase (DLD), reoxidizes the reduced lipoamide arm of E2 and transfers electrons to NAD+, forming NADH. This completes the catalytic cycle and regenerates the oxidized enzyme for subsequent rounds. The same E3 component is shared with the 2-oxoadipate dehydrogenase complex, and both complexes can produce reactive oxygen species as byproducts.
Overall stoichiometry and metabolic context
In simple terms: In total, one molecule of 2-oxoglutarate is converted into succinyl-CoA, CO2, and NADH.
The three reactions can be summarized as: 2-oxoglutarate + coenzyme A + NAD+ -> succinyl-CoA + CO2 + NADH. This reaction is a key step in the TCA cycle and is also used in glutamate catabolism and amino acid oxidation pathways in organisms such as Thermococcus kodakarensis and Bacillus amyloliquefaciens. In some archaea, a distinct enzyme, 2-ketoglutarate ferredoxin oxidoreductase, can catalyze an analogous reaction.
Key Genes Involved in GO:0120551 2-oxoglutarate decarboxylation to succinyl-CoA
The following genes and proteins are directly involved in or closely associated with GO:0120551, based on the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| OGDH | E1 subunit of the 2-oxoglutarate dehydrogenase complex; catalyzes oxidative decarboxylation of 2-oxoglutarate | Core catalytic component; target for studying TCA cycle flux and ROS production |
| DLST | E2 subunit; forms the core of the complex and transfers succinyl groups to coenzyme A | Shared with the 2-oxoadipate dehydrogenase complex; key for assembly studies |
| DLD | E3 subunit; reoxidizes lipoamide and reduces NAD+ to NADH | Shared with other dehydrogenase complexes; linked to redox biology |
| MRPS36 | Structural link in the eukaryotic 2-oxoglutarate dehydrogenase complex | Mutations cause Leigh syndrome; emerging disease gene |
| OGDHL | 2-oxoglutarate dehydrogenase-like protein; may modulate complex activity | Potential regulatory subunit; less characterized |
| SUCLA2 | Succinyl-CoA synthetase, beta subunit; acts downstream of succinyl-CoA | Links GO:0120551 to succinyl-CoA metabolism |
| SUCLG1 | Succinyl-CoA synthetase, alpha subunit; acts downstream of succinyl-CoA | Mitochondrial disease gene; related pathway |
| SLC25A10 | Mitochondrial dicarboxylate carrier; transports 2-oxoglutarate and succinate | Affects substrate availability for the complex |
| GLS | Glutaminase; generates glutamate, which feeds into 2-oxoglutarate | Upstream regulator of substrate supply |
| GLUD1 | Glutamate dehydrogenase; converts glutamate to 2-oxoglutarate | Links amino acid catabolism to GO:0120551 |
| GOT1 | Aspartate aminotransferase; contributes to 2-oxoglutarate pools | Metabolic context |
| GOT2 | Mitochondrial aspartate aminotransferase; contributes to 2-oxoglutarate pools | Metabolic context |
| IDH2 | Isocitrate dehydrogenase 2; produces 2-oxoglutarate in mitochondria | Upstream of GO:0120551 |
| IDH3A | Isocitrate dehydrogenase 3 subunit; produces 2-oxoglutarate in TCA cycle | Upstream of GO:0120551 |
| DHTKD1 | 2-oxoadipate dehydrogenase; shares E2/E3 with OGDHC | Cross-talk with lysine metabolism |
| KGD1 | Yeast 2-oxoglutarate dehydrogenase E1 component | Model organism studies |
| KGD2 | Yeast dihydrolipoamide succinyltransferase E2 component | Model organism studies |
| LPD1 | Yeast dihydrolipoamide dehydrogenase E3 component | Model organism studies |
How Is 2-oxoglutarate decarboxylation to succinyl-CoA Regulated?
The 2-oxoglutarate dehydrogenase complex is regulated by substrate availability, product inhibition, and redox state. NADH and succinyl-CoA inhibit the complex, while calcium ions and ADP activate it in mitochondria. The recent identification of MRPS36 as a structural component suggests additional layers of assembly regulation in eukaryotes. The complex also shares E2 and E3 components with the 2-oxoadipate dehydrogenase complex, implying coordinated regulation of these pathways. In bacteria and archaea, alternative enzymes such as 2-ketoglutarate ferredoxin oxidoreductase can bypass the OGDHC, providing metabolic flexibility.
2-oxoglutarate decarboxylation to succinyl-CoA and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MRPS36 | Leigh syndrome due to biallelic variants | Knockout or point-mutation cell models; patient-derived fibroblasts |
| OGDH | Mitochondrial encephalopathy; TCA cycle dysfunction | CRISPR knockout in HEK293 or HeLa cells |
| DLST | Mitochondrial disease; shared with 2-oxoadipate dehydrogenase complex | Knockout and rescue with wild-type or mutant DLST |
| DLD | Redox imbalance; ROS production | Point-mutation knock-in to mimic patient variants |
| DHTKD1 | Charcot-Marie-Tooth disease; cross-talk with OGDHC | Overexpression and knockout models |
Leigh Syndrome and Mitochondrial Encephalopathy
Biallelic variants in MRPS36, a structural component of the eukaryotic 2-oxoglutarate dehydrogenase complex, cause a new form of Leigh syndrome, a severe mitochondrial disorder characterized by progressive neurodegeneration. This directly links GO:0120551 to human disease and highlights the importance of complex assembly for mitochondrial function.
Reactive Oxygen Species and Oxidative Stress
The 2-oxoglutarate dehydrogenase complex and the related 2-oxoadipate dehydrogenase complex generate reactive oxygen species, which can contribute to oxidative stress in mitochondria. This has implications for neurodegenerative diseases and aging, where mitochondrial ROS production is implicated.
Metabolic Disorders and Enzyme Deficiencies
Deficiencies in OGDHC components can impair TCA cycle flux and energy production, leading to lactic acidosis and neurological symptoms. Although rare, such defects are part of the differential diagnosis for mitochondrial diseases.
From 2-oxoglutarate decarboxylation to succinyl-CoA-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of OGDHC component impair TCA cycle flux? | CRISPR knockout of OGDH, DLST, or DLD in HEK293 cells |
| Do patient variants in MRPS36 cause Leigh syndrome? | Point-mutation knock-in of MRPS36 variants in iPSCs or cell lines |
| Can wild-type MRPS36 rescue the disease phenotype? | Knock-in of tagged wild-type MRPS36 for rescue experiments |
| What is the role of MRPS36 in complex assembly? | Tagged knock-in (e.g., FLAG or GFP) followed by immunoprecipitation |
| Does overexpression of OGDHL modulate complex activity? | Overexpression of OGDHL in cell lines |
| How does the complex generate ROS? | Knockout of DLD or DLST and measurement of ROS |
How to Study the 2-oxoglutarate decarboxylation to succinyl-CoA Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzyme-coupled succinate detection | Succinate formation from 2-oxoglutarate | Screening for inhibitors or activators of 2-oxoglutarate-dependent enzymes |
| Affinity purification-mass spectrometry | Protein composition of OGDHC | Identifying novel subunits like MRPS36 |
| 13C metabolic flux analysis | Flux through the TCA cycle | Quantifying 2-oxoglutarate decarboxylation in cells |
| ROS detection (Amplex Red, MitoSOX) | Reactive oxygen species production | Assessing oxidative stress from OGDHC |
| Western blotting | Protein expression levels of OGDH, DLST, DLD, MRPS36 | Validating knockout or overexpression |
| Immunoprecipitation | Protein-protein interactions | Studying complex assembly |
| CRISPR knockout screening | Gene essentiality and metabolic dependencies | Identifying genes required for GO:0120551 |
| RNA-seq | Transcriptional changes upon perturbation | Assessing compensatory pathways |
Enzyme Activity Assays
The activity of the 2-oxoglutarate dehydrogenase complex can be measured using enzyme-coupled assays that detect the formation of succinyl-CoA or succinate. For example, an assay for Fe(II)/2-oxoglutarate-dependent dioxygenases detects succinate formation through enzyme coupling. These assays are useful for screening inhibitors or assessing mutant activity.
Proteomics and Complex Analysis
Affinity purification followed by mass spectrometry can identify components of the OGDHC, as demonstrated by the identification of MRPS36 as a structural link. This approach is valuable for studying complex assembly and stoichiometry.
Metabolic Flux Analysis
Stable isotope tracing with 13C-labeled substrates can measure flux through the TCA cycle and specifically through GO:0120551. This method helps quantify the contribution of different carbon sources to succinyl-CoA production.
ROS Detection
Reactive oxygen species generated by the OGDHC can be measured using fluorescent probes such as Amplex Red or MitoSOX. Both the 2-oxoglutarate and 2-oxoadipate dehydrogenase complexes produce ROS, and this can be assessed in isolated mitochondria or intact cells.
How CRISPR Can Be Used to Study GO:0120551 2-oxoglutarate decarboxylation to succinyl-CoA
Knockout
CRISPR knockout of OGDH, DLST, DLD, or MRPS36 can abolish GO:0120551 activity, leading to impaired TCA cycle flux and altered mitochondrial metabolism. Such models are useful for studying the consequences of complex loss and for identifying compensatory pathways.
Point Mutation
Point mutations identified in patients, such as biallelic MRPS36 variants causing Leigh syndrome, can be introduced into cell lines using CRISPR base editing or homology-directed repair. These models help determine whether specific variants are pathogenic and how they affect complex assembly and activity.
Knock-in
Knock-in of tagged versions of OGDH, DLST, DLD, or MRPS36 (e.g., FLAG, HA, or GFP) allows for affinity purification and localization studies. This approach was instrumental in identifying MRPS36 as a structural link in the eukaryotic complex.
Overexpression
Overexpression of OGDHC components or related proteins such as OGDHL can be achieved by CRISPR activation or lentiviral delivery. This is useful for testing whether increased levels of a subunit enhance complex activity or rescue defects.
How EDITGENE Supports 2-oxoglutarate decarboxylation to succinyl-CoA Research
Researchers studying 2-oxoglutarate decarboxylation to succinyl-CoA-related genes often need to determine whether a candidate gene is causally involved in mitochondrial metabolism, complex assembly, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for 2-oxoglutarate decarboxylation to succinyl-CoA research.
Frequently Asked Questions About 2-oxoglutarate decarboxylation to succinyl-CoA
What is GO:0120551?
GO:0120551 is the Gene Ontology term for 2-oxoglutarate decarboxylation to succinyl-CoA, a biological process that converts 2-oxoglutarate into succinyl-CoA with release of CO2 and production of NADH, typically as part of the TCA cycle.
What genes are involved in 2-oxoglutarate decarboxylation to succinyl-CoA?
Key genes include OGDH (E1), DLST (E2), DLD (E3), and MRPS36, which encode components of the 2-oxoglutarate dehydrogenase complex.
What is the 2-oxoglutarate dehydrogenase complex?
It is a multienzyme complex composed of E1 (OGDH), E2 (DLST), and E3 (DLD) subunits, with MRPS36 as a structural link in eukaryotes, that catalyzes the conversion of 2-oxoglutarate to succinyl-CoA.
How is 2-oxoglutarate decarboxylation regulated?
The complex is regulated by substrate availability, product inhibition by NADH and succinyl-CoA, and calcium/ADP activation; MRPS36 may also play a role in assembly.
What diseases are associated with defects in this pathway?
Biallelic variants in MRPS36 cause a new form of Leigh syndrome, and other components are linked to mitochondrial disorders and oxidative stress.
How can I study 2-oxoglutarate decarboxylation in the lab?
Enzyme-coupled assays detecting succinate or succinyl-CoA formation, metabolic flux analysis, and CRISPR knockout models are commonly used.
What is the role of MRPS36 in the 2-oxoglutarate dehydrogenase complex?
MRPS36 provides a structural link in the eukaryotic complex, and its loss or mutation impairs complex function and causes disease.
Does the 2-oxoglutarate dehydrogenase complex produce reactive oxygen species?
Yes, both the 2-oxoglutarate and 2-oxoadipate dehydrogenase complexes can generate reactive oxygen species, contributing to mitochondrial oxidative stress.
Is 2-oxoglutarate decarboxylation conserved across species?
Yes, the pathway is conserved from bacteria and archaea to humans, although some archaea use alternative enzymes like 2-ketoglutarate ferredoxin oxidoreductase.
What CRISPR models are available for studying this pathway?
EDITGENE offers knockout, point-mutation knock-in, tagged knock-in, and overexpression models for genes such as OGDH, DLST, DLD, and MRPS36.
Conclusion
GO:0120551, 2-oxoglutarate decarboxylation to succinyl-CoA, is a fundamental mitochondrial process that bridges carbon and nitrogen metabolism and is essential for TCA cycle function. The 2-oxoglutarate dehydrogenase complex, comprising OGDH, DLST, DLD, and MRPS36, is a target for understanding mitochondrial bioenergetics, ROS production, and disease. Recent discoveries linking MRPS36 to Leigh syndrome underscore the clinical relevance of this pathway. By leveraging CRISPR-based models and advanced analytical methods, researchers can dissect the molecular mechanisms and therapeutic potential of this critical metabolic step.
References
- 1. Hevler JF et al.. 2023. MRPS36 provides a structural link in the eukaryotic 2-oxoglutarate dehydrogenase complex.. Open Biol 13(3):220363 PMID: 36854377
- 2. Nemeria NS et al.. 2018. The mitochondrial 2-oxoadipate and 2-oxoglutarate dehydrogenase complexes share their E2 and E3 components for their function and both generate reactive oxygen species.. Free Radic Biol Med 115:136-145 PMID: 29191460
- 3. Luo L et al.. 2006. An assay for Fe(II)/2-oxoglutarate-dependent dioxygenases by enzyme-coupled detection of succinate formation.. Anal Biochem 353(1):69-74 PMID: 16643838
- 4. Galosi S et al.. 2024. Biallelic Variants of MRPS36 Cause a New Form of Leigh Syndrome.. Mov Disord 39(7):1225-1231 PMID: 38685873
- 6. Yokooji Y et al.. 2013. Genetic examination of initial amino acid oxidation and glutamate catabolism in the hyperthermophilic archaeon Thermococcus kodakarensis.. J Bacteriol 195(9):1940-8 PMID: 23435976
- 7. Zhang W et al.. 2015. Deletion of genes involved in glutamate metabolism to improve poly-gamma-glutamic acid production in B. amyloliquefaciens LL3.. J Ind Microbiol Biotechnol 42(2):297-305 PMID: 25540046
- 8. Mai X et al.. 1996. Characterization of a fourth type of 2-keto acid-oxidizing enzyme from a hyperthermophilic archaeon: 2-ketoglutarate ferredoxin oxidoreductase from Thermococcus litoralis.. J Bacteriol 178(20):5890-6 PMID: 8830683
