GO:0047015 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047015 describes the molecular function 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity, which catalyzes the NAD+-dependent oxidation of 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA.
• This enzyme is a short-chain 3-hydroxy-2-methylacyl-CoA dehydrogenase purified and characterized from rat liver as a novel enzyme of isoleucine metabolism.
• Deficiency of 3-hydroxy-2-methylbutyryl-CoA dehydrogenase is a recognized inborn error of isoleucine catabolism associated with abnormal metabolite excretion.
• The reaction is reversible and uses NAD+ as the electron acceptor, producing NADH and H+.
• Researchers study this activity using enzyme assays, metabolomics, and CRISPR-engineered cell and animal models to dissect its role in branched-chain amino acid metabolism.
• Understanding GO:0047015 helps link genotype to biochemical phenotype in disorders of isoleucine degradation.
Description
GO:0047015, 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity, is a molecular function annotated in the Gene Ontology that catalyzes a specific step in the degradation of the branched-chain amino acid isoleucine. The reaction converts 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA using NAD+ as a cofactor, generating NADH and H+. This activity is distinct from other short-chain dehydrogenases because it acts on a 2-methyl-branched substrate. The enzyme was first purified and characterized from rat liver as a short-chain 3-hydroxy-2-methylacyl-CoA dehydrogenase, establishing it as a novel component of isoleucine metabolism. Clinically, deficiency of this activity has been reported as an inborn error of metabolism, highlighting its importance in human biochemistry. For researchers, GO:0047015 provides a precise functional annotation to study enzyme kinetics, metabolic flux, and disease mechanisms. Understanding this term is essential for interpreting genetic variants, designing metabolic experiments, and developing therapeutic strategies for related disorders.
3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity At A Glance
| GO ID | GO:0047015 |
|---|---|
| GO term | 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity |
| Ontology | molecular_function |
| Synonym | 2-methyl-3-hydroxybutyryl-CoA dehydrogenase activity; 2-methyl-3-hydroxy-butyryl CoA dehydrogenase activity; (2S,3S)-3-hydroxy-2-methylbutanoyl-CoA:NAD+ oxidoreductase activity |
| Major function | Catalyzes the NAD+-dependent oxidation of 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA in isoleucine catabolism |
| Reaction | NAD+ + 2-methyl-3-hydroxybutyryl-CoA = NADH + H+ + 2-methylaceto-acetyl-CoA |
| Cofactor | NAD+ |
| Pathway context | Isoleucine degradation |
| Enzyme class | Oxidoreductase (short-chain dehydrogenase/reductase family) |
What Is GO:0047015?
According to the Gene Ontology, GO:0047015 (3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity) is defined as the catalysis of the reaction: NAD+ + 2-methyl-3-hydroxybutyryl-CoA = NADH + H+ + 2-methylaceto-acetyl-CoA. In other words, it is an oxidoreductase that removes hydrogen from the hydroxyl group of 2-methyl-3-hydroxybutyryl-CoA, transferring electrons to NAD+ to form NADH, and yielding 2-methylacetoacetyl-CoA. This activity is synonymous with 2-methyl-3-hydroxybutyryl-CoA dehydrogenase activity and related names.
Why Is 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity Important in Cell Biology?
GO:0047015 is important because it represents a critical enzymatic step in the catabolism of isoleucine, a branched-chain amino acid. Defects in this activity lead to 3-hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency, an inborn error of metabolism that can present with abnormal urinary metabolite profiles and potentially neurological symptoms. Studying this activity helps researchers understand metabolic flux, diagnose metabolic disorders, and develop targeted therapies. The enzyme's specificity for 2-methyl-branched substrates distinguishes it from other short-chain dehydrogenases, making it a unique target for biochemical and structural studies.
• Enables the second step of isoleucine degradation, linking amino acid catabolism to energy production.
• Deficiency causes 3-hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency, a rare metabolic disorder.
• Provides a diagnostic marker for inborn errors of branched-chain amino acid metabolism.
• Serves as a model for studying short-chain dehydrogenase/reductase (SDR) enzyme mechanisms.
• Potential target for modulating isoleucine metabolism in metabolic diseases.
• Helps interpret genetic variants identified by newborn screening and exome sequencing.
• Contributes to understanding of organic acidemias and their clinical management.
• Facilitates research on enzyme kinetics and substrate specificity of 2-methyl-branched acyl-CoAs.
Molecular Mechanism of 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity
Substrate Recognition and Binding
In simple terms: The enzyme grabs a specific molecule called 2-methyl-3-hydroxybutyryl-CoA and holds it in place.
The enzyme specifically binds 2-methyl-3-hydroxybutyryl-CoA, a 2-methyl-branched acyl-CoA intermediate in isoleucine catabolism. The 2-methyl branch is critical for recognition, as the enzyme was purified as a short-chain 3-hydroxy-2-methylacyl-CoA dehydrogenase with specificity for this substrate. Binding involves the CoA moiety and the 2-methyl-3-hydroxybutyryl group, positioning the hydroxyl group for oxidation.
Catalytic Oxidation and NAD+ Reduction
In simple terms: The enzyme removes hydrogen from the substrate and transfers it to NAD+, turning NAD+ into NADH.
The catalytic mechanism involves oxidation of the 3-hydroxy group of 2-methyl-3-hydroxybutyryl-CoA, with NAD+ serving as the electron acceptor. This dehydrogenation produces 2-methylacetoacetyl-CoA, NADH, and H+. The reaction is reversible, allowing the enzyme to also catalyze the reverse reduction under appropriate conditions.
Role in Isoleucine Catabolism
In simple terms: This step helps break down the amino acid isoleucine to produce energy.
GO:0047015 catalyzes a step in the degradation of isoleucine, converting 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA. This intermediate is further metabolized to propionyl-CoA and acetyl-CoA, which enter the TCA cycle. The enzyme thus links branched-chain amino acid catabolism to central energy metabolism.
Enzyme Structure and Cofactor Requirements
In simple terms: The enzyme needs NAD+ to work and belongs to a large family of similar enzymes.
The enzyme is a short-chain 3-hydroxy-2-methylacyl-CoA dehydrogenase that requires NAD+ as a cofactor. It belongs to the short-chain dehydrogenase/reductase (SDR) superfamily, characterized by a Rossmann-fold NAD+-binding domain. The rat liver enzyme was purified and characterized, showing typical SDR properties.
Key Genes Involved in GO:0047015 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity
The following genes and proteins are directly or functionally associated with 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity (GO:0047015) and isoleucine metabolism.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HSD17B10 | Encodes a short-chain dehydrogenase/reductase with 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity | Mutations cause HSD10 disease; studied for isoleucine metabolism and neurodegeneration |
| ACAD8 | Isobutyryl-CoA dehydrogenase, involved in valine catabolism | Related branched-chain acyl-CoA dehydrogenase; comparative studies |
| ACADSB | Short/branched-chain acyl-CoA dehydrogenase, acts on 2-methylbutyryl-CoA | Adjacent step in isoleucine catabolism; deficiency causes 2-methylbutyrylglycinuria |
| HADH | Short-chain 3-hydroxyacyl-CoA dehydrogenase | Similar SDR enzyme; used for mechanistic comparisons |
| ECHS1 | Enoyl-CoA hydratase, short chain 1 | Catalyzes step before GO:0047015 in isoleucine oxidation |
| HADHA | Mitochondrial trifunctional protein alpha subunit | Long-chain 3-hydroxyacyl-CoA dehydrogenase; related family |
| HADHB | Mitochondrial trifunctional protein beta subunit | Beta-ketothiolase activity; downstream of GO:0047015 |
| ACAT1 | Acetyl-CoA acetyltransferase 1 | Thiolase that acts on 2-methylacetoacetyl-CoA |
| BCKDHA | Branched-chain keto acid dehydrogenase E1 alpha | Upstream regulator of isoleucine catabolism |
| BCKDHB | Branched-chain keto acid dehydrogenase E1 beta | Upstream regulator of isoleucine catabolism |
| DBT | Dihydrolipoamide branched chain transacylase E2 | Component of BCKD complex |
| DLD | Dihydrolipoamide dehydrogenase | Component of BCKD complex |
| PCCA | Propionyl-CoA carboxylase alpha subunit | Downstream metabolism of propionyl-CoA from isoleucine |
| PCCB | Propionyl-CoA carboxylase beta subunit | Downstream metabolism of propionyl-CoA |
| MUT | Methylmalonyl-CoA mutase | Downstream of propionyl-CoA in isoleucine catabolism |
| IVD | Isovaleryl-CoA dehydrogenase | Leucine catabolism; related acyl-CoA dehydrogenase |
| SLC25A20 | Carnitine-acylcarnitine translocase | Mitochondrial transport of acyl-CoAs |
| CPT2 | Carnitine palmitoyltransferase 2 | Mitochondrial fatty acid oxidation; related energy metabolism |
How Is 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity Regulated?
The activity of 3-hydroxy-2-methylbutyryl-CoA dehydrogenase is regulated at the level of substrate availability and NAD+/NADH ratio, as it depends on NAD+ as a cofactor. In the context of isoleucine catabolism, flux through the pathway is influenced by the activity of upstream enzymes such as branched-chain keto acid dehydrogenase (BCKDH) and downstream enzymes like 2-methylacetoacetyl-CoA thiolase. Hormonal and nutritional states that affect branched-chain amino acid metabolism may also modulate this activity, but specific transcriptional or allosteric regulation of the enzyme itself has not been extensively characterized in the provided literature.
3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HSD17B10 | HSD10 disease / 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency | Patient-derived fibroblasts, KO cell lines, knock-in mouse models |
| ACADSB | 2-Methylbutyrylglycinuria | KO cell lines, metabolic flux assays |
| ECHS1 | ECHS1 deficiency (Leigh-like syndrome) | KO cell lines, metabolomics |
| HADH | Hyperinsulinism-hyperammonemia syndrome | KO cell lines, insulin secretion assays |
| BCKDHA | Maple syrup urine disease | KO cell lines, enzyme activity assays |
3-Hydroxy-2-methylbutyryl-CoA Dehydrogenase Deficiency
Deficiency of 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity (GO:0047015) is an inborn error of isoleucine metabolism. Patients may present with abnormal urinary excretion of 2-methyl-3-hydroxybutyrate and other metabolites, and clinical features can include developmental delay, seizures, and metabolic acidosis. The disorder is diagnosed by biochemical profiling and enzyme assays, and management focuses on dietary restriction of isoleucine and supportive care.
HSD10 Disease (2-Methyl-3-Hydroxybutyryl-CoA Dehydrogenase Deficiency)
Mutations in HSD17B10, which encodes a multifunctional enzyme with 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity, cause HSD10 disease (also known as 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency). This X-linked disorder presents with progressive neurodegeneration, cardiomyopathy, and metabolic crises. The enzyme defect leads to accumulation of toxic metabolites and impaired isoleucine catabolism, highlighting the clinical importance of GO:0047015.
Broader Metabolic and Neurological Implications
Impaired isoleucine catabolism, including reduced GO:0047015 activity, can contribute to organic acidemias and neurological dysfunction. Understanding this enzyme's role may inform therapeutic strategies for related metabolic disorders and provide insights into mitochondrial energy metabolism.
From 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of GO:0047015 activity cause metabolic accumulation? | CRISPR knockout of HSD17B10 in HepG2 or HEK293 cells |
| What is the effect of a specific patient mutation on enzyme activity? | Point mutation knock-in of HSD17B10 variants |
| Can wild-type enzyme rescue the metabolic phenotype? | Knock-in of wild-type HSD17B10 or overexpression |
| How does the enzyme localize within mitochondria? | Tagged knock-in with GFP or FLAG tag |
| What are the downstream metabolic consequences of enzyme deficiency? | Overexpression of mutant vs. wild-type enzyme followed by metabolomics |
| Can small molecules modulate enzyme activity? | Overexpression system for high-throughput screening |
How to Study the 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Spectrophotometric NADH assay | Enzyme activity via NADH production | Kinetic characterization, deficiency diagnosis |
| GC-MS organic acid analysis | Metabolite levels in urine/plasma | Diagnosis of inborn errors of metabolism |
| LC-MS/MS metabolomics | Quantitative metabolite profiling | Pathway flux analysis |
| CRISPR-Cas9 knockout | Loss-of-function phenotype | Gene function studies |
| Site-directed mutagenesis | Effect of specific mutations | Structure-function analysis |
| Western blot | Protein expression levels | Validation of knockout/overexpression |
| Immunofluorescence | Subcellular localization | Mitochondrial targeting studies |
Enzyme Activity Assays
Direct measurement of 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity can be performed using spectrophotometric assays that monitor NADH production at 340 nm. Purified enzyme or cell lysates are incubated with substrate and NAD+, and the initial rate of NADH formation is recorded. This method is essential for confirming enzyme deficiency in patient samples and for kinetic characterization.
Metabolomics and Organic Acid Analysis
Gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) can quantify metabolites such as 2-methyl-3-hydroxybutyrate and 2-methylacetoacetate in urine or plasma. These analyses help diagnose deficiencies in isoleucine catabolism and assess the functional impact of GO:0047015 loss.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 can be used to generate knockout cell lines for genes encoding the enzyme, such as HSD17B10, to study loss-of-function phenotypes. Point mutations can be introduced to model patient-specific variants, and knock-in of tagged versions allows localization and interaction studies.
Protein Expression and Purification
Recombinant enzyme can be expressed in E. coli or mammalian cells and purified using affinity chromatography. Purified enzyme is used for crystallography, kinetic studies, and inhibitor screening.
How CRISPR Can Be Used to Study GO:0047015 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity
Knockout
CRISPR knockout of HSD17B10 or related genes can abolish 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity, creating cellular models of enzyme deficiency. These models are useful for studying metabolic consequences, such as accumulation of upstream metabolites and changes in isoleucine catabolism.
Point Mutation
Point mutations identified in patients with HSD10 disease can be introduced into cell lines using CRISPR prime editing or homology-directed repair. These models allow researchers to assess the impact of specific amino acid changes on enzyme activity and stability.
Knock-in
Knock-in of wild-type or tagged versions of the enzyme enables rescue experiments and localization studies. For example, a GFP-tagged knock-in can reveal mitochondrial targeting and dynamics.
Overexpression
Overexpression of the enzyme in cell lines can be achieved by lentiviral transduction or CRISPR activation. This is useful for biochemical purification, drug screening, and studying the effects of increased enzyme activity on metabolic flux.
How EDITGENE Supports 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity Research
Researchers studying 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity-related genes often need to determine whether a candidate gene is causally involved in metabolic pathways or disease phenotypes. EDITGENE provides comprehensive CRISPR-based services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity research.
Frequently Asked Questions About 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity
What is 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity?
It is a molecular function (GO:0047015) that catalyzes the NAD+-dependent oxidation of 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA, a step in isoleucine catabolism.
What genes are involved in 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity?
The primary gene is HSD17B10, which encodes a multifunctional enzyme with this activity. Other genes in the isoleucine pathway include ACADSB, ECHS1, and BCKDHA.
What is the reaction catalyzed by GO:0047015?
NAD+ + 2-methyl-3-hydroxybutyryl-CoA = NADH + H+ + 2-methylaceto-acetyl-CoA.
What diseases are associated with 3-hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency?
Deficiency causes 3-hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency and HSD10 disease, which can present with neurological and metabolic symptoms.
How is 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity measured?
It is typically measured using spectrophotometric assays that monitor NADH production at 340 nm, or by metabolomic profiling of urine organic acids.
What is the role of this enzyme in isoleucine metabolism?
It catalyzes the conversion of 2-methyl-3-hydroxybutyryl-CoA to 2-methylacetoacetyl-CoA, a key step in the degradation of isoleucine.
Can CRISPR be used to study GO:0047015?
Yes, CRISPR knockout, point mutation, and knock-in models can be generated to study the function of HSD17B10 and related genes.
What are the symptoms of HSD10 disease?
Symptoms may include developmental delay, seizures, cardiomyopathy, and metabolic acidosis.
Is 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity reversible?
Yes, the reaction is reversible, and the enzyme can catalyze both oxidation and reduction depending on conditions.
Where is the enzyme located in the cell?
It is a mitochondrial enzyme involved in isoleucine catabolism.
Conclusion
GO:0047015, 3-hydroxy-2-methylbutyryl-CoA dehydrogenase activity, is a critical enzymatic function in isoleucine catabolism with direct clinical relevance to inborn errors of metabolism such as HSD10 disease. Understanding its mechanism, regulation, and genetic basis provides insights into metabolic disorders and potential therapeutic targets. Researchers can leverage CRISPR-based models and biochemical assays to further dissect this pathway and develop interventions.
References
- 1. Sutton VR et al.. 2003. 3-Hydroxy-2-methylbutyryl-CoA dehydrogenase deficiency.. J Inherit Metab Dis 26(1):69-71 PMID: 12872843
- 2. Luo MJ et al.. 1995. Short-chain 3-hydroxy-2-methylacyl-CoA dehydrogenase from rat liver: purification and characterization of a novel enzyme of isoleucine metabolism.. Arch Biochem Biophys 321(1):214-20 PMID: 7639524
