GO:0160166 2-oxoadipate dehydrogenase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0160166 defines the molecular function 2-oxoadipate dehydrogenase activity, which catalyzes the oxidative decarboxylation of 2-oxoadipate to glutaryl-CoA within the mitochondrial 2-oxoadipate dehydrogenase complex (OADHC).
• The reaction requires a lipoylated E2 component (dihydrolipoyllysine-residue succinyltransferase) and produces CO2 and a glutarylated dihydrolipoyl moiety on the enzyme.
• The human OADHC is encoded by DHTKD1 (E1), DLST (E2), and DLD (E3), and it shares E2 and E3 with the 2-oxoglutarate dehydrogenase complex (OGDHC).
• OADHC is a major source of mitochondrial reactive oxygen species (ROS) when 2-oxoadipate accumulates, linking the enzyme to redox signaling and oxidative stress.
• Inhibition or dysfunction of 2-oxoadipate dehydrogenase causes protein glutarylation and metabolic remodeling, with relevance to neurological and metabolic disorders.
• DHTKD1 variants, such as G729R, alter OADHC structure and function and are associated with a disorder of L-lysine metabolism, making the enzyme a target for functional genomics and drug discovery.
Description
2-Oxoadipate dehydrogenase activity (GO:0160166) is a mitochondrial molecular function that catalyzes the oxidative decarboxylation of 2-oxoadipate, a key intermediate in L-lysine and tryptophan catabolism, to glutaryl-CoA. This reaction is performed by the 2-oxoadipate dehydrogenase complex (OADHC), a multienzyme assembly that is closely related to the 2-oxoglutarate dehydrogenase complex (OGDHC) and shares its E2 and E3 components. The enzyme is encoded by DHTKD1 (E1), DLST (E2), and DLD (E3) in humans, and its activity is essential for maintaining metabolic flux through the glutarate pathway. Researchers study this term because it sits at the intersection of mitochondrial energy metabolism, redox biology, and inherited metabolic disease. The OADHC is not only a catabolic hub but also a source of reactive oxygen species (ROS), particularly when 2-oxoadipate accumulates or when the enzyme is inhibited. This dual role makes it a compelling target for understanding how mitochondrial dysfunction contributes to neurodegeneration, metabolic disorders, and potentially cancer. Moreover, the enzyme's dependence on lipoic acid and its shared components with OGDHC create a unique regulatory landscape that can be probed with genetic and pharmacological tools. In this article, we integrate the QuickGO definition of GO:0160166 with verified PubMed literature to provide a research-grade overview of the enzyme's mechanism, key genes, disease associations, and experimental models. We also highlight how CRISPR-based approaches can be used to dissect the function of DHTKD1 and its partners in health and disease.
2-oxoadipate dehydrogenase activity At A Glance
| GO ID | GO:0160166 |
|---|---|
| GO term | 2-oxoadipate dehydrogenase activity |
| Ontology | molecular_function |
| Synonym | none |
| Major function | Catalyzes oxidative decarboxylation of 2-oxoadipate to glutaryl-CoA within the OADHC |
| Reaction | 2-oxoadipate + H+ + lipoyl-E2 = CO2 + glutaryl-dihydrolipoyl-E2 |
| Cofactors | Thiamine pyrophosphate (TPP), lipoic acid, CoA, NAD+ |
| Complex components | E1 (DHTKD1), E2 (DLST), E3 (DLD) |
| Subcellular location | Mitochondrial matrix |
| Related pathway | L-lysine degradation, tryptophan metabolism, glutarate pathway |
What Is GO:0160166?
2-Oxoadipate dehydrogenase activity (GO:0160166) is defined as the catalysis of the reaction: 2-oxoadipate + H+ + N(6)-[(R)-lipoyl]-L-lysyl-[dihydrolipoyllysine-residue succinyltransferase] = CO2 + N(6)-[(R)-S(8)-glutaryldihydrolipoyl]-L-lysyl-[dihydrolipoyllysine-residue succinyltransferase]. In simpler terms, it is the enzyme activity that removes a carboxyl group from 2-oxoadipate as carbon dioxide and transfers the remaining glutaryl group to a lipoyl-modified lysine residue on the E2 subunit of the dehydrogenase complex. This reaction is a component of the 2-oxoadipate dehydrogenase complex (OADHC), which is involved in L-lysine catabolism and mitochondrial metabolism.
Why Is 2-oxoadipate dehydrogenase activity Important in Cell Biology?
2-Oxoadipate dehydrogenase activity is important because it controls the flux of 2-oxoadipate, a metabolite that can accumulate in inherited disorders and contribute to mitochondrial dysfunction. The enzyme is a major source of ROS in mitochondria, and its inhibition leads to protein glutarylation, a post-translational modification that can alter enzyme activities and cellular signaling. DHTKD1 mutations cause a disorder of L-lysine metabolism, and the enzyme has been implicated in neurological and metabolic phenotypes in animal models. Understanding GO:0160166 therefore provides insight into mitochondrial bioenergetics, redox homeostasis, and the pathogenesis of rare and common diseases.
• Provides a key step in L-lysine and tryptophan catabolism, linking amino acid breakdown to energy production.
• Shares E2 and E3 components with OGDHC, making it a modulator of the Krebs cycle and mitochondrial ROS production.
• Its inhibition causes protein glutarylation, a PTM that can affect multiple metabolic enzymes.
• DHTKD1 mutations are associated with a disorder of L-lysine metabolism and neurological symptoms.
• The enzyme is a source of superoxide/hydrogen peroxide, contributing to redox signaling and oxidative stress.
• Pharmacological inhibitors of 2-oxoadipate dehydrogenase elicit target-specific metabolic and physiological responses in rats.
• It is a potential target for treating metabolic disorders linked to glutarate accumulation.
• Studying its structure-function relationships can guide drug design and genetic variant interpretation.
• CRISPR models of DHTKD1 can reveal tissue-specific roles and compensatory pathways.
• The enzyme's activity can be measured to assess mitochondrial health in disease models.
Molecular Mechanism of 2-oxoadipate dehydrogenase activity
Substrate recognition and binding
In simple terms: The enzyme grabs 2-oxoadipate and holds it in place for chemical modification.
The E1 subunit of the 2-oxoadipate dehydrogenase complex, encoded by DHTKD1, binds 2-oxoadipate in a pocket that positions the substrate for decarboxylation. Structural studies of the G729R variant show that mutations near the active site can alter substrate affinity and catalytic efficiency. The enzyme requires thiamine pyrophosphate (TPP) as a cofactor to initiate the reaction.
Oxidative decarboxylation and acyl transfer
In simple terms: The enzyme removes a carbon dioxide molecule and passes the rest to a flexible arm on the complex.
Upon binding, 2-oxoadipate undergoes decarboxylation, releasing CO2 and forming a glutaryl-TPP intermediate. The glutaryl group is then transferred to the lipoyl moiety of the E2 subunit (dihydrolipoyllysine-residue succinyltransferase, DLST), forming a glutaryl-dihydrolipoyl intermediate. This step is analogous to the mechanism of other 2-oxoacid dehydrogenase complexes, such as pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase.
Electron transfer and NADH production
In simple terms: The complex regenerates its lipoyl arm and produces NADH, a carrier of chemical energy.
The dihydrolipoyl moiety on E2 is reoxidized by the E3 component (dihydrolipoamide dehydrogenase, DLD), which transfers electrons to NAD+ to produce NADH. This step is shared with the 2-oxoglutarate dehydrogenase complex, as both complexes use the same E2 and E3 components. The generation of NADH links 2-oxoadipate oxidation to the electron transport chain and ATP production.
Reactive oxygen species production
In simple terms: When the enzyme is overloaded, it can leak electrons and create harmful oxygen radicals.
The 2-oxoadipate dehydrogenase complex can generate superoxide and hydrogen peroxide, especially when 2-oxoadipate accumulates or when the enzyme is inhibited. This ROS production is a side reaction of the flavin-containing E3 component and can contribute to oxidative stress. The balance between NADH production and ROS generation is influenced by substrate availability and the redox state of the mitochondria.
Regulation by lipoylation and inhibitors
In simple terms: The enzyme needs a lipoic acid tag to work, and certain chemicals can block it.
The activity of the complex depends on the lipoylation of the E2 subunit, which is mediated by lipoic acid synthesis pathways. Defects in lipoic acid synthesis can impair 2-oxoadipate dehydrogenase activity and lead to metabolic disease. Phosphonate inhibitors of 2-oxoglutarate and 2-oxoadipate dehydrogenases can selectively modulate enzyme activity in vivo, affecting metabolic and physiological responses.
Key Genes Involved in GO:0160166 2-oxoadipate dehydrogenase activity
The following genes encode the structural and regulatory components of the 2-oxoadipate dehydrogenase complex and related pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| DHTKD1 | E1 subunit of OADHC; binds 2-oxoadipate and catalyzes decarboxylation | Mutations cause a disorder of L-lysine metabolism; target for functional studies |
| DLST | E2 subunit; transfers glutaryl groups and is shared with OGDHC | Lipoylation site; central to complex assembly and ROS production |
| DLD | E3 subunit; reoxidizes lipoamide and produces NADH | Shared with OGDHC and PDHC; links to redox balance |
| OGDH | E1 subunit of OGDHC; can use 2-oxoadipate as alternative substrate | Contributes to ROS production from 2-oxoadipate |
| LIAS | Lipoic acid synthase; required for lipoylation of E2 subunits | Defects cause lipoic acid synthesis disorders |
| LIPT1 | Lipoyltransferase; attaches lipoate to E2 | Mutations affect multiple dehydrogenase complexes |
| LIPT2 | Lipoyltransferase; involved in lipoate synthesis | Related to lipoic acid metabolism |
| SLC25A1 | Mitochondrial citrate carrier; may influence 2-oxoadipate levels | Indirect role in substrate supply |
| AASS | Alpha-aminoadipate semialdehyde synthase; upstream in lysine degradation | Provides 2-oxoadipate for OADHC |
| DHTKD1 variants | G729R and others alter enzyme structure and function | Modeled in vitro and in cells to study disease |
| GOT2 | Aspartate aminotransferase; links amino acid metabolism to TCA cycle | May affect 2-oxoadipate availability |
| MDH2 | Malate dehydrogenase; TCA cycle enzyme | Context for metabolic flux |
| IDH3A | Isocitrate dehydrogenase; TCA cycle | Related to mitochondrial metabolism |
| SDHA | Succinate dehydrogenase; TCA cycle | Potential compensatory pathways |
| FH | Fumarase; TCA cycle | Metabolic context |
| ACO2 | Aconitase; TCA cycle | Metabolic context |
| CS | Citrate synthase; TCA cycle | Metabolic context |
| MPC1 | Mitochondrial pyruvate carrier | Supports acetyl-CoA production |
How Is 2-oxoadipate dehydrogenase activity Regulated?
The activity of 2-oxoadipate dehydrogenase is regulated at multiple levels. Substrate availability of 2-oxoadipate, derived from L-lysine and tryptophan catabolism, directly influences flux through the complex. The lipoylation status of the E2 subunit is critical, and defects in lipoic acid synthesis or attachment reduce enzyme activity. The complex shares E2 and E3 with OGDHC, so competition for these components can affect overall flux. Additionally, pharmacological inhibitors can acutely modulate activity, and the enzyme's ROS-producing side reaction is sensitive to the mitochondrial redox environment. Protein glutarylation, a consequence of OADHC inhibition, may further regulate enzyme activities in a feedback manner.
2-oxoadipate dehydrogenase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| DHTKD1 | Disorder of L-lysine metabolism; neurological symptoms | Knockout or point-mutation cell lines; patient-derived fibroblasts |
| DLST | Lipoic acid synthesis defects; metabolic dysfunction | Knockdown in cell lines; lipoylation assays |
| DLD | Redox imbalance; ROS production | Overexpression and knockout models; ROS measurements |
| OGDH | Alternative substrate use; ROS generation | Knockout cells; substrate flux analysis |
| LIAS | Lipoic acid synthesis disorder | CRISPR knockout; metabolic profiling |
Disorders of L-lysine metabolism
Mutations in DHTKD1, the E1 subunit of the 2-oxoadipate dehydrogenase complex, cause a rare disorder of L-lysine metabolism characterized by elevated 2-oxoadipate and neurological symptoms. The G729R variant specifically impairs enzyme function and has been structurally characterized. Diagnosis often involves measuring urinary organic acids and genetic testing, and functional studies are needed to confirm pathogenicity.
Mitochondrial dysfunction and oxidative stress
Inhibition of 2-oxoadipate dehydrogenase leads to increased protein glutarylation and altered brain metabolism in rats, suggesting a link to mitochondrial dysfunction. The enzyme is a source of ROS, and its overactivity or substrate overload can contribute to oxidative stress in neurons and other tissues. This has implications for neurodegenerative conditions where mitochondrial ROS play a role.
Metabolic and pharmacological responses
Phosphonate inhibitors of 2-oxoglutarate and 2-oxoadipate dehydrogenases elicit target-specific metabolic and physiological responses in rats, highlighting the enzyme as a potential drug target. Modulating its activity could influence glutarate levels and related metabolic pathways. However, the therapeutic window must be carefully evaluated due to the enzyme's role in ROS production.
From 2-oxoadipate dehydrogenase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does DHTKD1 loss alter 2-oxoadipate levels? | DHTKD1 knockout cell line (e.g., HEK293 or HepG2) |
| How does the G729R variant affect enzyme activity? | Point-mutation knock-in of DHTKD1 G729R in cell lines |
| What is the role of lipoylation in OADHC function? | Knockout of LIAS or LIPT1; rescue with lipoate |
| Does OADHC inhibition cause protein glutarylation? | Pharmacological inhibition in rat brain or cultured neurons |
| Can OADHC produce ROS under substrate overload? | Overexpression of DHTKD1 and DLST; ROS probes |
| What are the metabolic consequences of OADHC deficiency? | Metabolomics and proteomics in knockout models |
How to Study the 2-oxoadipate dehydrogenase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NADH production assay | Enzyme activity | Variant characterization, inhibitor screening |
| Amplex Red / MitoSOX | ROS generation | Mitochondrial oxidative stress |
| Anti-glutaryl-lysine Western blot | Protein glutarylation | OADHC inhibition readout |
| LC-MS metabolomics | 2-oxoadipate and related metabolites | Pathway flux analysis |
| CRISPR knockout | Gene function loss | DHTKD1, DLST, DLD studies |
| Point-mutation knock-in | Variant-specific effects | G729R and other DHTKD1 variants |
| Proteomics | Global protein expression and PTMs | Downstream effects of OADHC dysfunction |
| Seahorse respirometry | Mitochondrial respiration | Bioenergetic consequences |
Enzymatic activity assays
2-Oxoadipate dehydrogenase activity can be measured spectrophotometrically by monitoring NADH production at 340 nm using 2-oxoadipate as substrate and the purified complex or mitochondrial lysates. This assay is useful for characterizing variants and inhibitors.
ROS detection
The production of superoxide and hydrogen peroxide by the complex can be measured using fluorescent probes such as Amplex Red or MitoSOX in isolated mitochondria or intact cells. These methods help assess the oxidative side reaction of OADHC.
Protein glutarylation analysis
Glutarylation of proteins can be detected by Western blot with anti-glutaryl-lysine antibodies or by mass spectrometry after immunoprecipitation. This readout reflects OADHC inhibition and metabolic stress.
Genetic and pharmacological perturbation
CRISPR knockout or point-mutation knock-in of DHTKD1, DLST, or DLD can be combined with pharmacological inhibitors to dissect pathway-specific effects. Metabolomics and proteomics then reveal downstream consequences.
How CRISPR Can Be Used to Study GO:0160166 2-oxoadipate dehydrogenase activity
Knockout
CRISPR knockout of DHTKD1, DLST, or DLD can create cell models to study loss of 2-oxoadipate dehydrogenase activity. These models are useful for measuring substrate accumulation, ROS production, and compensatory metabolic pathways.
Point Mutation
Point-mutation knock-in of disease-associated variants such as DHTKD1 G729R allows precise modeling of altered enzyme function. Such models can reveal structural and biochemical consequences that are not evident from knockout alone.
Knock-in
Knock-in of tagged DHTKD1 or DLST (e.g., FLAG or GFP) enables affinity purification and imaging of the complex in live cells. This approach helps track complex assembly and subcellular localization.
Overexpression
Overexpression of DHTKD1 and DLST can amplify OADHC activity and ROS production, providing a system to study oxidative stress and substrate overload. It can also be used to rescue knockout phenotypes.
How EDITGENE Supports 2-oxoadipate dehydrogenase activity Research
Researchers studying 2-oxoadipate dehydrogenase activity-related genes often need to determine whether a candidate gene is causally involved in metabolic or neurological phenotypes. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this discovery process, from knockout to precise point mutations and overexpression.
Contact EDITGENE today to design your custom CRISPR model for 2-oxoadipate dehydrogenase activity research.
Frequently Asked Questions About 2-oxoadipate dehydrogenase activity
What is 2-oxoadipate dehydrogenase activity?
It is the enzyme activity defined by GO:0160166 that catalyzes the oxidative decarboxylation of 2-oxoadipate to glutaryl-CoA within the mitochondrial 2-oxoadipate dehydrogenase complex.
What genes are involved in 2-oxoadipate dehydrogenase activity?
The main genes are DHTKD1 (E1), DLST (E2), and DLD (E3), which encode the subunits of the complex.
What is the role of DHTKD1 in metabolism?
DHTKD1 encodes the E1 subunit that binds 2-oxoadipate and initiates its decarboxylation, linking lysine catabolism to mitochondrial energy production.
How is 2-oxoadipate dehydrogenase activity measured?
It is typically measured by monitoring NADH production at 340 nm using 2-oxoadipate as substrate, or by detecting ROS and protein glutarylation.
What diseases are associated with 2-oxoadipate dehydrogenase deficiency?
Mutations in DHTKD1 cause a disorder of L-lysine metabolism with neurological symptoms, and enzyme inhibition leads to protein glutarylation and metabolic changes.
Does 2-oxoadipate dehydrogenase produce reactive oxygen species?
Yes, the complex can generate superoxide and hydrogen peroxide, especially when 2-oxoadipate accumulates or the enzyme is inhibited.
What is the difference between OADHC and OGDHC?
They are related multienzyme complexes that share E2 and E3 components; OADHC uses 2-oxoadipate as substrate, while OGDHC primarily uses 2-oxoglutarate.
Can CRISPR be used to study 2-oxoadipate dehydrogenase activity?
Yes, CRISPR knockout, point-mutation knock-in, and overexpression models are powerful tools to dissect the function of DHTKD1, DLST, and DLD.
What are the cofactors required for 2-oxoadipate dehydrogenase activity?
The complex requires thiamine pyrophosphate (TPP), lipoic acid, coenzyme A, and NAD+ for catalysis.
How does lipoylation affect 2-oxoadipate dehydrogenase activity?
Lipoylation of the E2 subunit is essential for activity; defects in lipoic acid synthesis or attachment impair the complex and cause metabolic disease.
Conclusion
2-Oxoadipate dehydrogenase activity (GO:0160166) is a critical mitochondrial function that bridges amino acid catabolism, energy production, and redox biology. Its complex architecture, shared components with OGDHC, and capacity for ROS generation make it a fascinating subject for metabolic research. Disease-associated variants in DHTKD1 highlight its clinical relevance, and CRISPR-based models offer powerful ways to study its mechanism and regulation. As the field moves toward precision models of metabolic disease, targeting 2-oxoadipate dehydrogenase activity with genetic and pharmacological tools will likely yield new insights into mitochondrial dysfunction and potential therapies.
References
- 2. Boyko AI et al.. 2022. Delayed Impact of 2-Oxoadipate Dehydrogenase Inhibition on the Rat Brain Metabolism Is Linked to Protein Glutarylation.. Front Med (Lausanne) 9:896263 PMID: 35721081
- 3. 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
- 4. Boyko AI et al.. 2020. Isoforms of the DHTKD1-Encoded 2-Oxoadipate Dehydrogenase, Identified in Animal Tissues, Are not Observed upon the Human DHTKD1 Expression in Bacterial or Yeast Systems.. Biochemistry (Mosc) 85(8):920-929 PMID: 33045952
- 5. Zhang X et al.. 2020. Structure-function analyses of the G729R 2-oxoadipate dehydrogenase genetic variant associated with a disorder of l-lysine metabolism.. J Biol Chem 295(23):8078-8095 PMID: 32303640
- 6. Nemeria NS et al.. 2017. The human Krebs cycle 2-oxoglutarate dehydrogenase complex creates an additional source of superoxide/hydrogen peroxide from 2-oxoadipate as alternative substrate.. Free Radic Biol Med 108:644-654 PMID: 28435050
- 7. Tort F et al.. 2016. Differential diagnosis of lipoic acid synthesis defects.. J Inherit Metab Dis 39(6):781-793 PMID: 27586888
- 8. Bunik VI et al.. 2022. Administration of Phosphonate Inhibitors of Dehydrogenases of 2-Oxoglutarate and 2-Oxoadipate to Rats Elicits Target-Specific Metabolic and Physiological Responses.. Front Chem 10:892284 PMID: 35795216
