GO:0008260 succinyl-CoA:3-oxo-acid CoA-transferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0008260 describes the enzymatic activity that transfers coenzyme A from succinyl-CoA to a 3-oxo acid, producing succinate and a 3-oxoacyl-CoA.
• In mammals, this activity is essential for ketone body catabolism (ketolysis), allowing tissues such as brain, heart, and skeletal muscle to use acetoacetate and beta-hydroxybutyrate for energy.
• The canonical enzyme is OXCT1 (succinyl-CoA:3-ketoacid CoA transferase), a mitochondrial matrix protein that is highly expressed in extrahepatic tissues.
• Deficiency of this activity causes succinyl-CoA:3-ketoacid CoA transferase deficiency, a rare inborn error of metabolism presenting with episodic ketoacidosis in infancy.
• OXCT1 is regulated by succinylation and by interaction with SUCLA2, and its activity can be modulated pharmacologically, with implications for cancer and diabetes.
• Research on this activity employs enzyme assays, CRISPR knockout and point-mutation models, metabolomics, and structural studies across species from mammals to trypanosomes.
Description
GO:0008260, succinyl-CoA:3-oxo-acid CoA-transferase activity, is a molecular function that catalyzes the reversible transfer of coenzyme A from succinyl-CoA to a 3-oxo acid, yielding succinate and a 3-oxoacyl-CoA. This activity is best known for its role in ketone body catabolism, where it facilitates the conversion of acetoacetate to acetoacetyl-CoA, a key step in ketolysis. The enzyme responsible, OXCT1 (also known as SCOT), is a mitochondrial matrix protein that is widely expressed in extrahepatic tissues but absent from the liver. Because ketone bodies are critical alternative fuels during fasting, prolonged exercise, and neonatal development, this activity is central to energy homeostasis. Dysregulation of succinyl-CoA:3-oxo-acid CoA-transferase activity has been linked to metabolic disorders, cancer, and rare inherited diseases. For example, loss-of-function mutations in OXCT1 cause succinyl-CoA:3-ketoacid CoA transferase deficiency, a disorder characterized by severe ketoacidosis in infancy. In cancer, OXCT1-mediated ketolysis supports tumor growth in the liver, and its activity is regulated by succinylation and interaction with SUCLA2. In obesity and diabetes, inhibiting skeletal muscle ketone oxidation can improve glycemia, highlighting the therapeutic potential of targeting this activity. Researchers study GO:0008260 using biochemical assays, genetic models, and structural biology. The enzyme has been purified from rat brain and other tissues, and comparative studies have revealed tissue-specific isoforms and kinetic properties. More recently, CRISPR-based knockout and point-mutation models have been used to dissect the roles of specific residues and regulatory modifications. This article provides a comprehensive overview of the mechanism, genes, regulation, disease relevance, and research methods associated with succinyl-CoA:3-oxo-acid CoA-transferase activity.
succinyl-CoA:3-oxo-acid CoA-transferase activity At A Glance
| GO ID | GO:0008260 |
|---|---|
| GO term | succinyl-CoA:3-oxo-acid CoA-transferase activity |
| Ontology | molecular_function |
| Synonym | 3-oxoacid CoA-transferase activity; acetoacetate succinyl-CoA transferase activity; succinyl-CoA:3-ketoacid-CoA transferase; succinyl-CoA transferase activity |
| Major function | Catalyzes the transfer of CoA from succinyl-CoA to a 3-oxo acid, producing succinate and a 3-oxoacyl-CoA; essential for ketone body catabolism |
| Reaction | succinyl-CoA + a 3-oxo acid = succinate + a 3-oxo-acyl-CoA |
| Cellular location | Mitochondrial matrix |
| Key enzyme | OXCT1 (SCOT) in mammals; homologs in other organisms |
| Related disease | Succinyl-CoA:3-ketoacid CoA transferase deficiency; cancer; diabetes |
What Is GO:0008260?
Succinyl-CoA:3-oxo-acid CoA-transferase activity (GO:0008260) is defined as the catalysis of the reaction: succinyl-CoA + a 3-oxo acid = succinate + a 3-oxo-acyl-CoA. In other words, it is an enzyme activity that moves a coenzyme A (CoA) group from succinyl-CoA onto a 3-oxo acid, producing succinate and a 3-oxoacyl-CoA. This reaction is reversible and is a key step in ketone body utilization, allowing the body to convert acetoacetate into acetoacetyl-CoA for further metabolism.
Why Is succinyl-CoA:3-oxo-acid CoA-transferase activity Important in Cell Biology?
Succinyl-CoA:3-oxo-acid CoA-transferase activity is essential for ketone body utilization, a process that provides energy to extrahepatic tissues during fasting, prolonged exercise, and neonatal life. By enabling the conversion of acetoacetate to acetoacetyl-CoA, it allows ketone bodies to enter the tricarboxylic acid cycle and support ATP production. This activity is also critical for brain development and function, as ketone bodies are important fuels for the developing brain. Moreover, dysregulation of this activity contributes to metabolic disorders such as ketoacidosis, and its inhibition has emerged as a potential strategy for treating obesity and diabetes. In cancer, OXCT1-mediated ketolysis supports tumor growth, making it a candidate therapeutic target.
• Enables ketone body catabolism, providing an alternative energy source during fasting and starvation.
• Supports brain metabolism, especially in neonates where ketone bodies are major fuels.
• Deficiency causes life-threatening ketoacidosis in infancy, highlighting its clinical importance.
• Plays a role in cancer metabolism, as OXCT1 supports liver tumor growth.
• Inhibition of skeletal muscle ketone oxidation improves glycemia in obesity models.
• Regulated by succinylation and protein-protein interactions, offering targets for therapeutic modulation.
• Studied across species, from mammals to Trypanosoma brucei, revealing conserved and divergent features.
• Its activity can be measured biochemically, making it a tractable enzyme for drug discovery.
Mechanism, Genes and Research Methods
Biological Process: Ketone Body Catabolism
In simple terms: This enzyme helps the body break down ketone bodies to make energy when glucose is scarce.
Succinyl-CoA:3-oxo-acid CoA-transferase activity is a key step in ketone body catabolism, also known as ketolysis. During fasting or prolonged exercise, the liver produces ketone bodies such as acetoacetate and beta-hydroxybutyrate from fatty acids. These ketone bodies are released into the bloodstream and taken up by extrahepatic tissues, including the brain, heart, and skeletal muscle. Inside mitochondria, acetoacetate is converted to acetoacetyl-CoA by succinyl-CoA:3-oxo-acid CoA-transferase, using succinyl-CoA as the CoA donor. The resulting acetoacetyl-CoA is then cleaved by thiolase into two molecules of acetyl-CoA, which enter the TCA cycle to produce ATP. This pathway is essential for energy homeostasis during periods of low carbohydrate availability.
Cellular Component: Mitochondrial Matrix Localization
In simple terms: The enzyme works inside mitochondria, the powerhouses of the cell.
Succinyl-CoA:3-oxo-acid CoA-transferase activity is localized to the mitochondrial matrix, where it colocalizes with other enzymes of ketone body metabolism and the TCA cycle. The enzyme is a soluble protein that does not require membrane association for activity. In mammals, the enzyme is encoded by the nuclear gene OXCT1 and imported into mitochondria via a mitochondrial targeting sequence. The mitochondrial matrix environment provides the necessary substrates, including succinyl-CoA, which is generated by the TCA cycle and by succinyl-CoA synthetase (SUCLA2/SUCLG2). The enzyme's activity is influenced by the availability of succinyl-CoA and by post-translational modifications such as succinylation.
Molecular Function: Catalytic Mechanism and Substrate Specificity
In simple terms: The enzyme grabs a CoA group from succinyl-CoA and hands it to a 3-oxo acid, like passing a baton.
The catalytic mechanism of succinyl-CoA:3-oxo-acid CoA-transferase involves a ping-pong kinetic mechanism. First, succinyl-CoA binds to the enzyme, and the CoA group is transferred to an active-site glutamate residue, forming a glutamyl-CoA thioester intermediate and releasing succinate. Next, a 3-oxo acid (e.g., acetoacetate) binds and accepts the CoA group, forming a 3-oxoacyl-CoA (e.g., acetoacetyl-CoA) and regenerating the free enzyme. This mechanism is conserved across species, although the specific residues involved can vary; for example, a single amino acid residue in the Trypanosoma brucei enzyme modulates its activity. The enzyme exhibits broad specificity for 3-oxo acids, including acetoacetate, and can also use other 3-oxo acids.
Regulation by Succinylation and Protein Interactions
In simple terms: The enzyme's activity can be switched on or off by chemical tags and by binding to other proteins.
Recent studies have shown that OXCT1, the enzyme responsible for succinyl-CoA:3-oxo-acid CoA-transferase activity, is regulated by succinylation. Specifically, succinylation of OXCT1 at specific lysine residues can inhibit its activity, while the mitochondrial enzyme SUCLA2 can promote its desuccinylation and activation. This regulation is important for ketolysis and liver tumor growth, as SUCLA2-mediated activation of OXCT1 supports cancer cell proliferation. Additionally, the enzyme's activity can be modulated by small-molecule inhibitors, such as pimozide, which inhibits skeletal muscle ketone oxidation and improves glycemia in obesity models. These findings highlight the potential for pharmacological targeting of this activity.
Tissue-Specific Expression and Isoforms
In simple terms: Different tissues have different versions of the enzyme, tuned to their energy needs.
Succinyl-CoA:3-oxo-acid CoA-transferase activity is present in most extrahepatic tissues, with high levels in the brain, heart, and skeletal muscle, but is absent from the liver. This tissue distribution ensures that ketone bodies produced by the liver are oxidized in peripheral tissues. In the testis, a haploid germ cell-specific homolog of the enzyme, known as OXCT2, has been identified, suggesting specialized roles in sperm metabolism. Comparative studies in rats have shown that the enzyme from different tissues exhibits similar kinetic properties but may differ in regulation. The presence of tissue-specific isoforms and homologs underscores the importance of this activity in diverse physiological contexts.
Key Genes Involved in GO:0008260 succinyl-CoA:3-oxo-acid CoA-transferase activity
The following genes and proteins are directly involved in succinyl-CoA:3-oxo-acid CoA-transferase activity or its regulation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| OXCT1 | Encodes the main succinyl-CoA:3-ketoacid CoA transferase (SCOT) in mammals; catalyzes the rate-limiting step in ketolysis | Target for cancer and metabolic disease; regulated by succinylation |
| SUCLA2 | Encodes a subunit of succinyl-CoA synthetase; interacts with OXCT1 and promotes its desuccinylation and activation | Modulates ketolysis and tumor growth; potential therapeutic target |
| OXCT2 | Testis-specific homolog of OXCT1; may play a role in sperm metabolism | Studied for germ cell-specific functions and fertility |
| ACAT1 | Mitochondrial acetoacetyl-CoA thiolase; acts downstream of OXCT1 to cleave acetoacetyl-CoA into acetyl-CoA | Involved in ketone body utilization and is a target for metabolic studies |
| BDH1 | Catalyzes the interconversion of beta-hydroxybutyrate and acetoacetate; supplies substrate for OXCT1 | Regulates ketone body flux and is studied in diabetes and cancer |
| HMGCS2 | Rate-limiting enzyme for ketogenesis in the liver; produces ketone bodies that are utilized by OXCT1 in extrahepatic tissues | Target for understanding ketone body metabolism and fasting |
| SLC16A1 | Monocarboxylate transporter 1; transports ketone bodies into cells | Regulates ketone body uptake and is studied in metabolic disorders |
| SLC16A7 | Monocarboxylate transporter 2; facilitates ketone body transport in muscle and brain | Potential target for modulating ketone oxidation |
| PPARA | Peroxisome proliferator-activated receptor alpha; regulates expression of genes involved in fatty acid oxidation and ketogenesis | Influences ketone body metabolism and OXCT1 expression |
| INSR | Insulin receptor; signaling suppresses ketogenesis and promotes glucose utilization | Links insulin signaling to ketone body metabolism |
| FOXO1 | Forkhead box O1; transcription factor that promotes gluconeogenesis and ketogenesis during fasting | Regulates metabolic adaptation and OXCT1 expression |
| PGC1A | PPAR gamma coactivator 1 alpha; master regulator of mitochondrial biogenesis and oxidative metabolism | Modulates mitochondrial function and ketone oxidation |
| AMPK | AMP-activated protein kinase; energy sensor that promotes fatty acid oxidation and ketogenesis | Regulates energy homeostasis and OXCT1 activity |
| SIRT3 | NAD-dependent deacetylase sirtuin 3; regulates mitochondrial protein acetylation and succinylation | Modulates OXCT1 activity through post-translational modifications |
| SIRT5 | NAD-dependent desuccinylase sirtuin 5; removes succinyl groups from mitochondrial proteins | Regulates OXCT1 succinylation and ketolysis |
| GOT2 | Mitochondrial aspartate aminotransferase; contributes to succinyl-CoA pool | Indirectly affects OXCT1 activity by supplying succinyl-CoA |
| DLST | Dihydrolipoamide S-succinyltransferase; component of the alpha-ketoglutarate dehydrogenase complex; produces succinyl-CoA | Influences succinyl-CoA availability for OXCT1 |
| SUCLG1 | Encodes the alpha subunit of succinyl-CoA synthetase; forms complexes with SUCLA2 | Regulates succinyl-CoA levels and OXCT1 activity |
How Is succinyl-CoA:3-oxo-acid CoA-transferase activity Regulated?
Succinyl-CoA:3-oxo-acid CoA-transferase activity is regulated at multiple levels. At the post-translational level, OXCT1 is subject to succinylation, which inhibits its activity; the mitochondrial enzyme SUCLA2 promotes desuccinylation and activation of OXCT1, thereby enhancing ketolysis. This regulation is critical for liver tumor growth, as SUCLA2-mediated activation of OXCT1 supports cancer cell proliferation. At the transcriptional level, the expression of OXCT1 and other ketolytic genes is influenced by fasting and hormonal signals, including insulin and glucagon. Insulin suppresses ketogenesis and promotes glucose utilization, while glucagon and fasting induce ketogenesis and ketolysis. Additionally, the activity can be pharmacologically modulated; for example, pimozide inhibits skeletal muscle ketone oxidation and improves glycemia in diet-induced obesity. A selective peripheral inhibitor of succinyl-CoA:3-ketoacid CoA transferase has also been developed, which improves glycemia in obesity models. These regulatory mechanisms highlight the potential for therapeutic targeting of this activity in metabolic diseases and cancer.
succinyl-CoA:3-oxo-acid CoA-transferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| OXCT1 | Succinyl-CoA:3-ketoacid CoA transferase deficiency; episodic ketoacidosis in infancy | Oxct1 knockout mouse; patient-derived fibroblasts; CRISPR knock-in of patient mutations |
| OXCT1 | Liver cancer; ketolysis supports tumor growth | Hepatocellular carcinoma cell lines with OXCT1 knockout or overexpression; xenograft models |
| OXCT1 | Diabetes and obesity; inhibition improves glycemia | Diet-induced obese mice treated with OXCT1 inhibitors; skeletal muscle-specific knockout |
| SUCLA2 | Regulates OXCT1 activity and ketolysis; potential role in cancer | SUCLA2 knockout cells; co-immunoprecipitation and succinylation assays |
| OXCT2 | Testis-specific homolog; potential role in fertility | Oxct2 knockout mice; sperm motility and metabolism assays |
Succinyl-CoA:3-ketoacid CoA transferase deficiency
Deficiency of succinyl-CoA:3-oxo-acid CoA-transferase activity, caused by mutations in OXCT1, leads to a rare inborn error of metabolism known as succinyl-CoA:3-ketoacid CoA transferase deficiency. This condition typically presents in infancy with episodes of severe ketoacidosis, often triggered by fasting or illness. Because the enzyme is absent in the liver but present in extrahepatic tissues, the deficiency impairs ketone body utilization, leading to accumulation of ketone bodies and metabolic acidosis. Diagnosis is based on clinical presentation, elevated ketone bodies, and genetic testing. Treatment involves avoiding fasting and providing a high-carbohydrate diet, but management can be challenging.
Cancer metabolism
Recent studies have implicated succinyl-CoA:3-oxo-acid CoA-transferase activity in cancer. In liver cancer, OXCT1-mediated ketolysis supports tumor growth by providing acetyl-CoA for biosynthetic pathways. The activity of OXCT1 is regulated by succinylation and by interaction with SUCLA2, which promotes its activation and enhances ketolysis. Knockdown or inhibition of OXCT1 reduces tumor growth in preclinical models, suggesting that targeting this activity could be a therapeutic strategy for liver cancer. Furthermore, the enzyme may play a role in other cancers where ketone bodies serve as an energy source, although further research is needed.
Diabetes and obesity
In obesity and type 2 diabetes, increased ketone body oxidation in skeletal muscle contributes to hyperglycemia. Inhibiting succinyl-CoA:3-oxo-acid CoA-transferase activity with pimozide or a selective peripheral inhibitor reduces ketone oxidation and improves glycemia in diet-induced obese mice. These findings suggest that targeting this activity in skeletal muscle could be a novel approach to treat diabetes. The mechanism involves reducing the use of ketone bodies as fuel, which may force muscle to use glucose, thereby lowering blood glucose levels. Clinical trials are needed to evaluate the safety and efficacy of such inhibitors in humans.
Neurological and developmental roles
The brain relies on ketone bodies as an alternative fuel during development and fasting. Succinyl-CoA:3-oxo-acid CoA-transferase activity is essential for ketone body utilization in the brain, and its deficiency can lead to neurological symptoms during ketoacidotic episodes. In rat brain, the enzyme has been purified and characterized, showing high activity in regions with high energy demand. Understanding its role in brain metabolism may provide insights into neurodevelopmental disorders and neurodegenerative diseases, although direct links remain to be established.
From succinyl-CoA:3-oxo-acid CoA-transferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of OXCT1 loss on ketone body metabolism? | OXCT1 knockout cell lines (e.g., HEK293T, HepG2) and mouse models |
| How does succinylation regulate OXCT1 activity? | Point-mutation knock-in of specific lysine residues (e.g., K succinylation sites) in OXCT1 |
| What is the role of SUCLA2 in OXCT1 activation? | SUCLA2 knockout or overexpression models; co-immunoprecipitation and succinylation assays |
| Can OXCT1 inhibition improve glycemia in obesity? | Diet-induced obese mice treated with OXCT1 inhibitors (e.g., pimozide) |
| What is the impact of OXCT1 on tumor growth? | Xenograft models with OXCT1 knockout or overexpression in liver cancer cells |
| How does OXCT2 function in sperm metabolism? | Oxct2 knockout mice; sperm motility and metabolite profiling |
How to Study the succinyl-CoA:3-oxo-acid CoA-transferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Spectrophotometric enzyme assay | Enzyme activity by monitoring CoA transfer | Kinetic characterization and inhibitor screening |
| Metabolomics (LC-MS/GC-MS) | Levels of ketone bodies and acyl-CoAs | Profiling metabolic changes in cells and tissues |
| 13C isotopic tracing | Flux through ketolysis pathway | Quantifying metabolic flux in cancer and diabetes models |
| CRISPR knockout | Loss-of-function effects on ketone metabolism | Validating gene function in cell lines and mice |
| CRISPR point mutation | Effect of specific residues on enzyme activity | Studying post-translational modifications and catalytic residues |
| Western blot and immunoprecipitation | Protein expression and interactions | Assessing OXCT1 succinylation and SUCLA2 binding |
| X-ray crystallography | Three-dimensional structure of enzyme | Understanding catalytic mechanism and inhibitor design |
| Inhibitor treatment (e.g., pimozide) | Pharmacological modulation of activity | Testing therapeutic potential in obesity and diabetes |
Enzyme activity assays
Succinyl-CoA:3-oxo-acid CoA-transferase activity can be measured spectrophotometrically by coupling the reaction to a reporter system. Typically, the assay monitors the formation of acetoacetyl-CoA from acetoacetate and succinyl-CoA, which can be detected by the decrease in absorbance of succinyl-CoA at 310 nm or by using a coupled enzyme system with thiolase and NADH. These assays are used to determine kinetic parameters, substrate specificity, and the effects of inhibitors or mutations.
Metabolomics and flux analysis
Metabolomic profiling using mass spectrometry can quantify ketone bodies and their metabolites in cells and tissues. Stable isotope tracing with 13C-labeled ketone bodies can measure flux through the ketolysis pathway, providing insights into the role of succinyl-CoA:3-oxo-acid CoA-transferase activity in metabolic networks. These methods are particularly useful for studying cancer metabolism and diabetes.
Genetic and CRISPR models
CRISPR-Cas9 genome editing is widely used to create knockout, point-mutation, and knock-in models for studying succinyl-CoA:3-oxo-acid CoA-transferase activity. Knockout of OXCT1 or SUCLA2 in cell lines and mice allows researchers to assess the consequences of loss of function on ketolysis and disease phenotypes. Point mutations can be introduced to study the effects of specific residues on enzyme activity and regulation, such as succinylation sites. These models are essential for validating therapeutic targets.
Structural and biophysical methods
X-ray crystallography and cryo-electron microscopy can provide structural insights into the enzyme's active site and mechanism. For example, structural studies of the Trypanosoma brucei enzyme have revealed how a single amino acid residue modulates activity. Biophysical techniques such as isothermal titration calorimetry and surface plasmon resonance can measure substrate binding and inhibitor interactions. These methods aid in the design of selective inhibitors.
How CRISPR Can Be Used to Study GO:0008260 succinyl-CoA:3-oxo-acid CoA-transferase activity
Knockout
CRISPR-Cas9 knockout of OXCT1 or SUCLA2 is used to eliminate succinyl-CoA:3-oxo-acid CoA-transferase activity and study its consequences. For example, OXCT1 knockout in liver cancer cells reduces ketolysis and tumor growth. In skeletal muscle, OXCT1 knockout mice display impaired ketone oxidation and altered glucose homeostasis. These models are valuable for validating the role of the enzyme in metabolic diseases and cancer.
Point Mutation
CRISPR-mediated point mutations can be introduced to study the effects of specific amino acid residues on enzyme activity. For instance, mutation of lysine residues in OXCT1 that are subject to succinylation can reveal how this modification regulates activity. Similarly, mutations in the active site of the Trypanosoma brucei enzyme have been used to identify residues critical for catalysis. These models provide mechanistic insights into the enzyme's function.
Knock-in
Knock-in models can be used to express tagged or mutant versions of OXCT1 at endogenous levels. For example, a FLAG-tagged OXCT1 knock-in cell line allows for immunoprecipitation and proteomic analysis of interacting proteins. Knock-in of patient-derived mutations can recapitulate disease phenotypes in cell and animal models, aiding in the development of targeted therapies.
Overexpression
Overexpression of OXCT1 or SUCLA2 using CRISPR activation or lentiviral vectors can enhance succinyl-CoA:3-oxo-acid CoA-transferase activity. This approach is used to study the effects of increased ketolysis on cell metabolism and tumor growth. Overexpression models can also be used to test the efficacy of inhibitors in the presence of high enzyme levels.
How EDITGENE Supports succinyl-CoA:3-oxo-acid CoA-transferase activity Research
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Frequently Asked Questions About succinyl-CoA:3-oxo-acid CoA-transferase activity
What is succinyl-CoA:3-oxo-acid CoA-transferase activity?
It is an enzyme activity (GO:0008260) that transfers coenzyme A from succinyl-CoA to a 3-oxo acid, producing succinate and a 3-oxoacyl-CoA. This reaction is essential for ketone body catabolism.
What genes are involved in succinyl-CoA:3-oxo-acid CoA-transferase activity?
The main gene is OXCT1, which encodes the enzyme succinyl-CoA:3-ketoacid CoA transferase (SCOT). Other related genes include SUCLA2, which regulates OXCT1 activity, and OXCT2, a testis-specific homolog.
What diseases are associated with succinyl-CoA:3-oxo-acid CoA-transferase deficiency?
Deficiency of this activity causes succinyl-CoA:3-ketoacid CoA transferase deficiency, a rare disorder presenting with episodic ketoacidosis in infancy. It has also been implicated in cancer and diabetes.
How is succinyl-CoA:3-oxo-acid CoA-transferase activity measured?
It is typically measured using spectrophotometric enzyme assays that monitor the formation of acetoacetyl-CoA or the disappearance of succinyl-CoA. Coupled enzyme assays and metabolomics can also be used.
What is the role of OXCT1 in cancer?
OXCT1-mediated ketolysis supports tumor growth in liver cancer by providing acetyl-CoA for biosynthetic pathways. Its activity is regulated by succinylation and SUCLA2.
Can succinyl-CoA:3-oxo-acid CoA-transferase activity be inhibited therapeutically?
Yes, inhibitors such as pimozide and a selective peripheral inhibitor have been shown to improve glycemia in obesity models by blocking ketone oxidation in skeletal muscle.
Where is succinyl-CoA:3-oxo-acid CoA-transferase located in the cell?
It is located in the mitochondrial matrix, where it colocalizes with enzymes of ketone body metabolism and the TCA cycle.
What is the difference between OXCT1 and OXCT2?
OXCT1 is the main enzyme expressed in most extrahepatic tissues, while OXCT2 is a testis-specific homolog that may play a role in sperm metabolism.
How does succinylation regulate succinyl-CoA:3-oxo-acid CoA-transferase activity?
Succinylation of OXCT1 inhibits its activity, while the enzyme SUCLA2 promotes desuccinylation and activation, enhancing ketolysis and tumor growth.
What model systems are used to study succinyl-CoA:3-oxo-acid CoA-transferase activity?
Common models include CRISPR knockout and point-mutation cell lines, mouse models (e.g., Oxct1 knockout), and purified enzyme assays from tissues such as rat brain.
Conclusion
Succinyl-CoA:3-oxo-acid CoA-transferase activity (GO:0008260) is a fundamental enzymatic function that enables ketone body utilization in extrahepatic tissues. Its main enzyme, OXCT1, is critical for energy homeostasis during fasting and development, and its dysregulation is linked to ketoacidosis, cancer, and diabetes. Recent research has revealed complex regulation by succinylation and protein interactions, offering new avenues for therapeutic intervention. Understanding this activity requires a combination of biochemical, genetic, and structural approaches, and CRISPR-based models are invaluable for dissecting its roles in health and disease. As the field advances, targeting succinyl-CoA:3-oxo-acid CoA-transferase activity may provide novel treatments for metabolic disorders and cancer. EDITGENE's suite of CRISPR services can support researchers in creating precise models to study this activity and accelerate drug discovery.
References
- 1. Guo D et al.. 2025. OXCT1 succinylation and activation by SUCLA2 promotes ketolysis and liver tumor growth.. Mol Cell 85(4):843-856.e6 PMID: 39862868
- 2. Russell JJ et al.. 1982. Purification and properties of succinyl-CoA:3-oxo-acid CoA-transferase from rat brain.. J Neurochem 38(5):1446-52 PMID: 6950030
- 3. Al Batran R et al.. 2020. Pimozide Alleviates Hyperglycemia in Diet-Induced Obesity by Inhibiting Skeletal Muscle Ketone Oxidation.. Cell Metab 31(5):909-919.e8 PMID: 32275862
- 4. Koga M et al.. 2000. Isolation and characterization of a haploid germ cell-specific novel complementary deoxyribonucleic acid; testis-specific homologue of succinyl CoA:3-Oxo acid CoA transferase.. Biol Reprod 63(6):1601-9 PMID: 11090426
- 5. Tildon JT et al.. 1972. Succinyl-CoA: 3-ketoacid CoA-transferase deficiency. A cause for ketoacidosis in infancy.. J Clin Invest 51(3):493-8 PMID: 4258782
- 6. Tabatabaei Dakhili SA et al.. 2025. Development of a succinyl CoA:3-ketoacid CoA transferase inhibitor selective for peripheral tissues that improves glycemia in obesity.. iScience 28(5):112336 PMID: 40454095
- 7. Mochizuki K et al.. 2026. Modulation of succinyl-CoA:3-ketoacid CoA transferase activity by a single amino acid residue in acetate:succinate CoA transferase from Trypanosoma brucei, the causative agent of African sleeping sickness.. Protein Sci 35(2):e70463 PMID: 41556494
- 8. Fenselau A et al.. 1974. Comparative studies on 3-oxo acid coenzyme A transferase from various rat tissues.. Biochem J 142(3):619-27 PMID: 4464844
