GO:0042709 succinate-CoA ligase complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0042709 (succinate-CoA ligase complex) is a heterodimeric mitochondrial enzyme complex that catalyzes the reversible conversion of succinyl-CoA to succinate and CoA, coupled to ATP or GTP formation.
• The complex is composed of an alpha subunit (SUCLG1) and a beta subunit (SUCLA2 for ATP-specific or SUCLG2 for GTP-specific), forming the only TCA cycle enzyme that generates high-energy phosphate bonds via substrate-level phosphorylation.
• Mutations in SUCLA2 and SUCLG1 cause succinate-CoA ligase deficiency, a severe mitochondrial disorder with phenotypes including Leigh syndrome, encephalomyopathy, and methylmalonic aciduria.
• Recent studies show that SUCLA2 and its beta subunit have extramitochondrial roles, including regulation of stress granule assembly, redox homeostasis, and cancer metastasis.
• The complex is a target of lysine succinylation, and its activity is linked to NAD+ metabolism and Sirt5-mediated desuccinylation.
• Research on this complex employs CRISPR knockout, point mutation, and knock-in models, combined with metabolomics, proteomics, and imaging to dissect its roles in mitochondrial bioenergetics and disease.
Description
The succinate-CoA ligase complex (GO:0042709) is a heterodimeric enzyme complex that plays a central role in the tricarboxylic acid (TCA) cycle by catalyzing the reversible hydrolysis of succinyl-CoA to succinate and coenzyme A, coupled with the synthesis of ATP or GTP. This complex is unique among TCA cycle enzymes because it directly generates a high-energy phosphate bond through substrate-level phosphorylation, making it essential for mitochondrial energy production. The complex is composed of an alpha subunit, encoded by SUCLG1, and a beta subunit, encoded by either SUCLA2 (ATP-forming) or SUCLG2 (GTP-forming), which dictate the nucleotide specificity of the enzyme. Beyond its canonical role in the TCA cycle, the succinate-CoA ligase complex has emerged as a critical player in mitochondrial and cellular physiology. Mutations in SUCLA2 and SUCLG1 are associated with a spectrum of mitochondrial disorders, including Leigh syndrome, encephalomyopathy, and methylmalonic aciduria, highlighting its importance in human health. Furthermore, recent studies have revealed extramitochondrial functions for the beta subunit, such as promoting stress granule assembly and regulating redox homeostasis, which can drive cancer metastasis. The complex is also subject to post-translational modifications like lysine succinylation, linking its activity to cellular metabolic states. For researchers, understanding the succinate-CoA ligase complex is crucial for dissecting mitochondrial bioenergetics, metabolic reprogramming in cancer, and the molecular basis of mitochondrial diseases. The availability of CRISPR-based models, including knockout, point mutation, and knock-in cell lines, enables precise interrogation of the complex's subunits and their roles in health and disease.
succinate-CoA ligase complex At A Glance
| GO ID | GO:0042709 |
|---|---|
| GO term | succinate-CoA ligase complex |
| Ontology | cellular_component |
| Synonym | none |
| Major function | Catalyzes the reversible conversion of succinyl-CoA to succinate and CoA, coupled to ATP or GTP synthesis |
| Subunit composition | Heterodimer of alpha (SUCLG1) and beta (SUCLA2 or SUCLG2) subunits |
| Subcellular location | Mitochondrial matrix |
| Pathway | Tricarboxylic acid (TCA) cycle |
| Nucleotide specificity | ATP-specific (SUCLA2) or GTP-specific (SUCLG2) beta subunits |
What Is GO:0042709?
The succinate-CoA ligase complex (GO:0042709) is a heterodimeric enzyme complex, usually composed of an alpha and a beta chain, that functions in the TCA cycle by hydrolyzing succinyl-CoA into succinate and CoA, thereby forming ATP or GTP.
Why Is succinate-CoA ligase complex Important in Cell Biology?
The succinate-CoA ligase complex is essential for mitochondrial energy metabolism and is the only TCA cycle enzyme that directly produces a high-energy phosphate bond via substrate-level phosphorylation. Its dysfunction leads to severe mitochondrial disorders, including Leigh syndrome and encephalomyopathy, and it has been implicated in cancer progression through extramitochondrial roles in stress granule assembly and redox regulation. Understanding this complex provides insights into mitochondrial bioenergetics, metabolic diseases, and potential therapeutic targets.
• Mutations in SUCLA2 and SUCLG1 cause succinate-CoA ligase deficiency, a severe mitochondrial disorder with phenotypes including Leigh syndrome, encephalomyopathy, and methylmalonic aciduria.
• The complex is a key enzyme in the TCA cycle, directly generating ATP or GTP through substrate-level phosphorylation.
• SUCLA2 beta subunit promotes stress granule assembly and regulates redox homeostasis, driving cancer metastasis.
• The complex is regulated by lysine succinylation and NAD+-dependent Sirt5 desuccinylation, linking it to cellular metabolic states.
• Defects in the complex lead to mitochondrial bioenergetic failure and locomotor defects, as shown in sucla2 mutant models.
• The complex is a target for structural studies, with crystal structures revealing binding mechanisms for succinate and CoA.
• It serves as a model for studying mitochondrial disease mechanisms and for developing CRISPR-based therapies.
• Its role in cancer metastasis highlights potential for therapeutic intervention in oncology.
• The complex is involved in the pathophysiology of infantile mitochondrial disorders.
• Research on this complex benefits from advanced CRISPR models to dissect subunit-specific functions.
What Happens During succinate-CoA ligase complex?
Substrate Binding and Catalysis
In simple terms: The enzyme grabs succinyl-CoA and a nucleotide, then breaks it down to make succinate and an energy molecule.
The succinate-CoA ligase complex binds succinyl-CoA and a nucleotide (ADP or GDP) in its active site, where the alpha and beta subunits coordinate the substrates. Structural studies have revealed the binding mode of succinate and CoA, showing that the enzyme undergoes conformational changes to facilitate catalysis. The reaction proceeds through a phosphorylated enzyme intermediate, leading to the formation of ATP or GTP and the release of succinate and CoA.
Nucleotide Specificity and Energy Production
In simple terms: Depending on which beta subunit is present, the enzyme makes either ATP or GTP, both of which are energy carriers.
The beta subunit determines whether the complex uses ADP (SUCLA2) or GDP (SUCLG2) as the phosphate acceptor, thereby producing ATP or GTP, respectively. This substrate-level phosphorylation is a key source of high-energy phosphates in the TCA cycle, particularly in tissues with high energy demands.
Role in the TCA Cycle
In simple terms: This enzyme is a step in the circular process that cells use to burn fuel and make energy.
The succinate-CoA ligase complex catalyzes the only step in the TCA cycle that generates a high-energy phosphate bond directly, converting succinyl-CoA to succinate while producing ATP or GTP. This reaction is reversible and can also function in the reverse direction to generate succinyl-CoA from succinate, depending on cellular conditions.
Extramitochondrial Functions
In simple terms: Parts of this enzyme can also work outside mitochondria to help cells cope with stress and control chemical balance.
Recent studies have shown that the SUCLA2 beta subunit localizes to stress granules and promotes their assembly, regulating redox homeostasis and driving cancer metastasis. This extramitochondrial role expands the functional repertoire of the succinate-CoA ligase complex beyond mitochondrial metabolism.
Key Genes Involved in GO:0042709 succinate-CoA ligase complex
The succinate-CoA ligase complex is encoded by several nuclear genes, with SUCLG1, SUCLA2, and SUCLG2 being the most directly involved in its structure and function.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SUCLG1 | Encodes the alpha subunit of the succinate-CoA ligase complex | Mutations cause succinate-CoA ligase deficiency with severe mitochondrial phenotypes |
| SUCLA2 | Encodes the ATP-specific beta subunit | Mutations linked to Leigh syndrome and mitochondrial DNA depletion; promotes stress granule assembly and cancer metastasis |
| SUCLG2 | Encodes the GTP-specific beta subunit | Determines GTP specificity; less commonly mutated but relevant for metabolic studies |
| SIRT5 | NAD+-dependent desuccinylase that regulates succinate-CoA ligase activity | Modulates mitochondrial bioenergetics and rescues sucla2 mutant phenotypes |
| SDHA | Succinate dehydrogenase subunit A, adjacent TCA cycle enzyme | Often studied in conjunction with succinate-CoA ligase for TCA cycle flux |
| SDHB | Succinate dehydrogenase subunit B | Used as a comparative marker for TCA cycle enzyme complexes |
| SDHC | Succinate dehydrogenase subunit C | Component of complex II, relevant for mitochondrial respiration studies |
| SDHD | Succinate dehydrogenase subunit D | Involved in TCA cycle and mitochondrial function |
| ACLY | ATP citrate lyase, produces acetyl-CoA and succinyl-CoA precursors | Links to succinyl-CoA availability for the complex |
| OGDH | Alpha-ketoglutarate dehydrogenase, produces succinyl-CoA | Upstream enzyme providing substrate for succinate-CoA ligase |
| DLST | Dihydrolipoamide succinyltransferase, component of OGDH complex | Supplies succinyl-CoA to the TCA cycle |
| GOT2 | Glutamate oxaloacetate transaminase 2, involved in amino acid metabolism | Indirectly affects succinyl-CoA levels |
| SLC25A10 | Mitochondrial dicarboxylate carrier, transports succinate | Affects substrate availability for the complex |
| SLC25A11 | Mitochondrial oxoglutarate carrier | Involved in TCA cycle intermediate transport |
| MDH2 | Malate dehydrogenase 2, TCA cycle enzyme | Adjacent step in the TCA cycle, used for pathway analysis |
| FH | Fumarate hydratase, TCA cycle enzyme | Downstream of succinate-CoA ligase, relevant for metabolic flux |
| IDH3A | Isocitrate dehydrogenase 3 alpha, TCA cycle enzyme | Upstream of succinyl-CoA production |
| NNT | Nicotinamide nucleotide transhydrogenase, maintains NADPH/NADH balance | Affects mitochondrial redox and complex activity |
How Is succinate-CoA ligase complex Regulated?
The succinate-CoA ligase complex is regulated at multiple levels. Its activity is influenced by substrate availability, particularly succinyl-CoA and nucleotides, which are tied to the metabolic state of the cell. Post-translational modifications, especially lysine succinylation, can modulate the complex; Sirt5, an NAD+-dependent desuccinylase, removes succinyl groups and restores mitochondrial bioenergetics in sucla2 mutant models. Additionally, the beta subunit's extramitochondrial role in stress granule assembly is regulated by stress conditions and redox status, linking the complex to cellular stress responses.
succinate-CoA ligase complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SUCLA2 | Leigh syndrome, mitochondrial DNA depletion, cancer metastasis | CRISPR knockout and point mutation cell lines, xenograft models |
| SUCLG1 | Fatal infantile lactic acidosis, encephalomyopathy | Knockout and knock-in models in cell lines and animal models |
| SUCLG2 | Metabolic disorders (rare) | Knockout and overexpression models for GTP-specific functions |
| SIRT5 | Mitochondrial bioenergetics, NAD+ metabolism | Overexpression and knockout models to study desuccinylation |
| SDHA | Leigh syndrome, cancer (paraganglioma) | Knockout models for TCA cycle dysfunction |
Succinate-CoA Ligase Deficiency and Mitochondrial Disorders
Mutations in SUCLA2 and SUCLG1 cause succinate-CoA ligase deficiency, a severe mitochondrial disorder characterized by encephalomyopathy, Leigh syndrome, and methylmalonic aciduria. Clinical phenotypes include developmental delay, hypotonia, and lactic acidosis, with genotype-phenotype correlations showing that SUCLG1 mutations often lead to more severe outcomes. These disorders highlight the critical role of the complex in mitochondrial energy metabolism and brain function.
Cancer Metastasis and Stress Granule Regulation
The SUCLA2 beta subunit promotes stress granule assembly, which regulates redox homeostasis and drives cancer metastasis. This extramitochondrial function links the succinate-CoA ligase complex to cancer progression, suggesting that targeting this pathway could be a therapeutic strategy for metastatic cancers.
NAD+ Metabolism and Bioenergetic Failure
NAD+ and Sirt5 restore mitochondrial bioenergetics failure and improve locomotor defects caused by sucla2 mutations, indicating that the complex is sensitive to NAD+ levels and sirtuin activity. This connection offers potential therapeutic avenues for mitochondrial diseases involving succinate-CoA ligase dysfunction.
From succinate-CoA ligase complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of SUCLA2 loss on mitochondrial respiration? | SUCLA2 knockout cell lines (e.g., HEK293, HeLa) |
| How do SUCLG1 mutations affect complex assembly? | SUCLG1 point mutation knock-in cell lines |
| Does SUCLA2 beta subunit localize to stress granules? | Tagged knock-in of SUCLA2 with fluorescent tag |
| Can Sirt5 overexpression rescue sucla2 mutant phenotypes? | Sirt5 overexpression in sucla2 mutant cells |
| What is the role of SUCLG2 in GTP production? | SUCLG2 knockout and overexpression models |
| How does succinylation regulate complex activity? | Point mutation of lysine residues in SUCLA2/SUCLG1 |
How to Study the succinate-CoA ligase complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| LC-MS metabolomics | Levels of succinyl-CoA, succinate, ATP/GTP | Assessing complex activity in knockout cells |
| 13C flux analysis | TCA cycle flux and substrate utilization | Quantifying metabolic rewiring |
| Succinylome proteomics | Lysine succinylation sites | Identifying post-translational regulation |
| Fluorescence microscopy | Subcellular localization of subunits | Visualizing stress granule recruitment |
| CRISPR knockout screening | Gene essentiality and synthetic lethality | Discovering modifiers of complex function |
| Western blot | Protein expression and modification | Validating knockout and overexpression |
| Seahorse respirometry | Mitochondrial respiration (OCR) | Measuring bioenergetic function |
| Co-immunoprecipitation | Protein-protein interactions | Identifying complex components and partners |
Metabolomics and Flux Analysis
Metabolomics, including LC-MS and GC-MS, is used to measure succinyl-CoA, succinate, and nucleotide levels in cells with CRISPR-edited succinate-CoA ligase subunits. Flux analysis with 13C-labeled substrates can trace TCA cycle activity and quantify the contribution of the complex to energy production.
Proteomics and Succinylation Profiling
Proteomic approaches, such as mass spectrometry-based succinylome analysis, identify lysine succinylation sites on the complex and its regulators. This helps elucidate post-translational regulation and crosstalk with Sirt5.
Imaging and Subcellular Localization
Fluorescence microscopy with tagged subunits (e.g., GFP-SUCLA2) reveals mitochondrial and extramitochondrial localization, including stress granules. Live-cell imaging can track complex dynamics under stress conditions.
CRISPR Screening and Functional Genomics
Genome-wide CRISPR knockout screens can identify synthetic lethal interactions and modifiers of succinate-CoA ligase complex function. These screens are powerful for uncovering novel pathways linked to the complex in cancer and metabolic diseases.
How CRISPR Can Be Used to Study GO:0042709 succinate-CoA ligase complex
Knockout
CRISPR knockout of SUCLA2, SUCLG1, or SUCLG2 in cell lines (e.g., HEK293, HeLa) abolishes complex activity, leading to impaired mitochondrial respiration and altered metabolite levels. These models are used to study the loss-of-function phenotypes associated with succinate-CoA ligase deficiency.
Point Mutation
Point mutations identified in patients (e.g., SUCLA2 or SUCLG1 missense mutations) can be introduced via CRISPR to model disease-specific effects on complex assembly and catalysis. These models help dissect genotype-phenotype correlations and test therapeutic interventions.
Knock-in
Knock-in of tagged subunits (e.g., FLAG-SUCLA2) allows for affinity purification and localization studies. Knock-in of disease-associated mutations recapitulates patient phenotypes in isogenic cell lines.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of SUCLA2, SUCLG1, or SIRT5 can rescue loss-of-function phenotypes and enhance mitochondrial bioenergetics. Overexpression models are useful for studying gain-of-function effects and therapeutic potential.
How EDITGENE Supports succinate-CoA ligase complex Research
Researchers studying succinate-CoA ligase complex-related genes often need to determine whether a candidate gene is causally involved in mitochondrial function, metabolic disease, or cancer progression. EDITGENE provides comprehensive CRISPR-based services to generate precise cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for succinate-CoA ligase complex research.
Frequently Asked Questions About succinate-CoA ligase complex
What is the succinate-CoA ligase complex?
The succinate-CoA ligase complex (GO:0042709) is a heterodimeric enzyme in the TCA cycle that converts succinyl-CoA to succinate and CoA, producing ATP or GTP.
What genes are involved in the succinate-CoA ligase complex?
The complex is encoded by SUCLG1 (alpha subunit), SUCLA2 (ATP-specific beta subunit), and SUCLG2 (GTP-specific beta subunit).
What diseases are associated with succinate-CoA ligase complex mutations?
Mutations in SUCLA2 and SUCLG1 cause succinate-CoA ligase deficiency, leading to Leigh syndrome, encephalomyopathy, and methylmalonic aciduria.
How is the succinate-CoA ligase complex regulated?
It is regulated by substrate availability, lysine succinylation, and NAD+-dependent Sirt5 desuccinylation.
What is the role of SUCLA2 in cancer?
SUCLA2 beta subunit promotes stress granule assembly, regulates redox homeostasis, and drives cancer metastasis.
How can I study the succinate-CoA ligase complex using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect subunit functions and disease mechanisms.
What is the structure of the succinate-CoA ligase complex?
It is a heterodimer of alpha and beta subunits, with crystal structures revealing substrate binding and catalytic mechanisms.
What is the difference between SUCLA2 and SUCLG2?
SUCLA2 encodes the ATP-specific beta subunit, while SUCLG2 encodes the GTP-specific beta subunit, determining the nucleotide produced.
Can Sirt5 rescue succinate-CoA ligase deficiency?
NAD+ and Sirt5 restore mitochondrial bioenergetics and improve locomotor defects in sucla2 mutant models.
What methods are used to measure succinate-CoA ligase activity?
Metabolomics, flux analysis, respirometry, and proteomics are commonly used to assess complex activity and regulation.
Conclusion
The succinate-CoA ligase complex (GO:0042709) is a critical mitochondrial enzyme that bridges TCA cycle metabolism and energy production, with far-reaching implications for mitochondrial diseases and cancer. Its heterodimeric structure, nucleotide specificity, and regulation by succinylation and NAD+ metabolism make it a compelling subject for basic and translational research. By leveraging CRISPR-based models and multi-omics approaches, researchers can uncover novel functions of the complex and develop targeted therapies for succinate-CoA ligase deficiency and related disorders. EDITGENE's comprehensive services empower these investigations with precision and scale.
References
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- 3. Carrozzo R et al.. 2016. Succinate-CoA ligase deficiency due to mutations in SUCLA2 and SUCLG1: phenotype and genotype correlations in 71 patients.. J Inherit Metab Dis 39(2):243-52 PMID: 26475597
- 4. Chinopoulos C. 2021. The Mystery of Extramitochondrial Proteins Lysine Succinylation.. Int J Mol Sci 22(11) PMID: 34199982
- 5. Huang J et al.. 2016. Structural basis for the binding of succinate to succinyl-CoA synthetase.. Acta Crystallogr D Struct Biol 72(Pt 8):912-21 PMID: 27487822
- 6. Carrozzo R et al.. 2007. Infantile mitochondrial disorders.. Biosci Rep 27(1-3):105-12 PMID: 17486440
- 7. Richard J et al.. 2026. NAD+ and Sirt5 restore mitochondrial bioenergetics failure and improve locomotor defects caused by sucla2 mutations.. JCI Insight 11(2) PMID: 41574612
- 8. Huang J et al.. 2015. Structure of GTP-specific succinyl-CoA synthetase in complex with CoA.. Acta Crystallogr F Struct Biol Commun 71(Pt 8):1067-71 PMID: 26249701
