GO:0004489 methylenetetrahydrofolate reductase [NAD(P)H] activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004489 describes the enzymatic activity that converts (6S)-5-methyl-5,6,7,8-tetrahydrofolate to (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate using NAD(P)+ as an electron acceptor.
• This activity is essential for folate-mediated one-carbon metabolism, linking the methionine cycle and nucleotide synthesis.
• The enzyme is a flavoprotein that can also catalyze a dihydropterin reductase reaction, indicating broader redox capabilities.
• The common C677T polymorphism in MTHFR reduces enzyme activity and is a candidate genetic risk factor for vascular disease and migraine.
• MTHFR activity is regulated by S-adenosylmethionine and dihydrofolate polyglutamates, providing feedback control.
• 5-Formyltetrahydrofolate can inhibit MTHFR by promoting conformational remodeling of its active site.
Description
Methylenetetrahydrofolate reductase (MTHFR) catalyzes the NAD(P)H-dependent reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a key step in folate metabolism. This reaction, annotated as GO:0004489, is the only way mammals synthesize 5-methyltetrahydrofolate, the primary methyl donor for the remethylation of homocysteine to methionine. Because it sits at the intersection of the methionine cycle and nucleotide biosynthesis, MTHFR activity influences DNA methylation, DNA synthesis, and cellular redox balance. Researchers study this activity to understand how genetic variants, such as the common C677T polymorphism, affect enzyme function and disease risk. The enzyme is also a target for antifolate drugs and a model for studying flavin-dependent redox catalysis. Understanding GO:0004489 is therefore critical for nutrition, cardiovascular biology, and cancer research.
methylenetetrahydrofolate reductase [NAD(P)H] activity At A Glance
| GO ID | GO:0004489 |
|---|---|
| GO term | methylenetetrahydrofolate reductase [NAD(P)H] activity |
| Ontology | molecular_function |
| Synonym | 5,10-methylenetetrahydrofolate reductase activity; MTHFR activity; MetF |
| Major function | Catalyzes the NAD(P)H-dependent reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate |
| Cofactor | FAD (flavin adenine dinucleotide) |
| Substrates | (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate, NAD(P)H |
| Products | (6S)-5-methyl-5,6,7,8-tetrahydrofolate, NAD(P)+ |
| Regulation | Inhibited by S-adenosylmethionine and 5-formyltetrahydrofolate; modulated by dihydrofolate polyglutamates |
What Is GO:0004489?
GO:0004489 is defined as the catalysis of the reaction: (6S)-5-methyl-5,6,7,8-tetrahydrofolate + NAD(P)+ = (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + NAD(P)H + H+. In other words, it is the oxidoreductase activity that interconverts methylated and methylene forms of tetrahydrofolate using NAD+ or NADP+ as an electron acceptor. The reaction is reversible in vitro but physiologically favors the formation of 5-methyltetrahydrofolate. The enzyme requires FAD as a cofactor and can also act on dihydropterin substrates.
Why Is methylenetetrahydrofolate reductase [NAD(P)H] activity Important in Cell Biology?
GO:0004489 is central to one-carbon metabolism, which supplies methyl groups for methionine synthesis, DNA methylation, and nucleotide production. Dysregulation of this activity leads to hyperhomocysteinemia, a risk factor for cardiovascular disease, and has been linked to neural tube defects, cancer, and neuropsychiatric disorders. The enzyme is also a target for antifolate drugs and a model for studying flavoenzyme mechanisms. Understanding its regulation and genetic variation is therefore essential for precision medicine and nutritional genomics.
• Maintains methionine cycle homeostasis by providing 5-methyltetrahydrofolate for homocysteine remethylation.
• Supports DNA synthesis by balancing folate pools for thymidylate and purine biosynthesis.
• Genetic variants like C677T alter enzyme activity and are associated with vascular disease and migraine.
• Serves as a target for antifolate chemotherapeutics and a model for flavin-dependent redox catalysis.
• Regulated by S-adenosylmethionine and dihydrofolate polyglutamates, linking methionine status to folate metabolism.
• Inhibited by 5-formyltetrahydrofolate, a natural folate derivative, through active-site conformational changes.
• Bacterial MTHFRs, such as that from Neisseria meningitidis, are studied for structural and mechanistic insights.
• Some anaerobic bacteria use a reduced-ferredoxin-dependent MTHFR, expanding the known diversity of this activity.
Molecular Mechanism of methylenetetrahydrofolate reductase [NAD(P)H] activity
Substrate Binding and Cofactor Requirements
In simple terms: The enzyme grabs its folate substrate and a helper molecule called FAD to start the reaction.
MTHFR binds (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate and NAD(P)H in a sequential manner. The enzyme is a flavoprotein that uses FAD as a cofactor to transfer electrons from NAD(P)H to the folate substrate. Structural studies of bacterial MTHFRs have revealed conserved active-site residues that coordinate the substrate and FAD.
Catalytic Cycle and Redox Chemistry
In simple terms: The enzyme transfers electrons to convert one form of folate into another.
The catalytic cycle involves hydride transfer from NAD(P)H to FAD, followed by reduction of the methylene group of the folate substrate to a methyl group. This results in the formation of (6S)-5-methyl-5,6,7,8-tetrahydrofolate and NAD(P)+. The reaction is reversible, but the equilibrium favors 5-methyltetrahydrofolate under physiological conditions.
Regulation by S-Adenosylmethionine and Folate Derivatives
In simple terms: The enzyme can be turned off by molecules that signal plenty of methyl groups or by certain folate forms.
MTHFR activity is allosterically inhibited by S-adenosylmethionine (SAM), the universal methyl donor, providing feedback control. Dihydrofolate and its polyglutamate analogues also modulate activity, linking folate status to enzyme function. Additionally, 5-formyltetrahydrofolate, a stable folate derivative, inhibits MTHFR by inducing conformational remodeling of the active site.
Dihydropterin Reductase Side Activity
In simple terms: The enzyme can also perform a different chemical reaction, showing it is versatile.
Purified pig liver MTHFR exhibits dihydropterin reductase activity, catalyzing the NADPH-dependent reduction of dihydropterin to tetrahydropterin. This side activity suggests that MTHFR may have broader roles in pterin metabolism beyond folate interconversion.
Structural Diversity Across Species
In simple terms: Different organisms have slightly different versions of this enzyme.
While mammalian MTHFR is a well-characterized flavoprotein, bacterial enzymes such as that from Neisseria meningitidis have been biochemically and structurally characterized, revealing conserved catalytic domains but variations in oligomeric state. Some anaerobic bacteria, like Clostridium ljungdahlii, use a heterodimeric reduced-ferredoxin-dependent MTHFR, indicating evolutionary adaptation to different redox environments.
Key Genes Involved in GO:0004489 methylenetetrahydrofolate reductase [NAD(P)H] activity
The following genes and proteins are directly involved in or regulate methylenetetrahydrofolate reductase [NAD(P)H] activity.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MTHFR | Encodes the enzyme responsible for GO:0004489 activity | Common C677T variant linked to vascular disease and migraine |
| MTR | Methionine synthase, uses 5-methyltetrahydrofolate to remethylate homocysteine | Downstream of MTHFR in one-carbon metabolism |
| MTRR | Methionine synthase reductase, regenerates MTR | Supports methionine cycle flux |
| CBS | Cystathionine beta-synthase, transsulfuration of homocysteine | Alternative homocysteine disposal pathway |
| SHMT1 | Serine hydroxymethyltransferase, generates 5,10-methylene-THF | Provides substrate for MTHFR |
| MTHFD1 | Methylenetetrahydrofolate dehydrogenase, interconverts folate forms | Supplies 5,10-methylene-THF |
| DHFR | Dihydrofolate reductase, regenerates tetrahydrofolate | Influences folate pool availability |
| TYMS | Thymidylate synthase, uses 5,10-methylene-THF for dTMP synthesis | Competes with MTHFR for substrate |
| MTHFD2 | Mitochondrial methylenetetrahydrofolate dehydrogenase | Mitochondrial one-carbon metabolism |
| FOLR1 | Folate receptor alpha, mediates folate uptake | Affects intracellular folate levels |
| SLC19A1 | Reduced folate carrier, transports folates | Determines substrate availability |
| MAT1A | Methionine adenosyltransferase, produces SAM | Regulates MTHFR via SAM levels |
| GNMT | Glycine N-methyltransferase, consumes SAM | Affects SAM/SAH ratio and MTHFR regulation |
| AHCY | S-adenosylhomocysteine hydrolase, hydrolyzes SAH | Links methylation to homocysteine |
| BHMT | Betaine-homocysteine methyltransferase | Alternative homocysteine remethylation pathway |
| MTHFS | Methenyltetrahydrofolate synthetase | Metabolizes 5-formyl-THF, an MTHFR inhibitor |
| MTHFR (bacterial) | Bacterial homologs, e.g., from Neisseria meningitidis | Model for structural and mechanistic studies |
| MetF (bacterial) | Clostridium ljungdahlii MTHFR | Reduced-ferredoxin-dependent activity |
How Is methylenetetrahydrofolate reductase [NAD(P)H] activity Regulated?
MTHFR activity is regulated at multiple levels. Allosteric inhibition by S-adenosylmethionine (SAM) provides feedback control: when SAM levels are high, MTHFR is inhibited, reducing 5-methyltetrahydrofolate production and conserving folate for nucleotide synthesis. Dihydrofolate and its polyglutamate analogues also modulate activity, linking folate status to enzyme function. Additionally, 5-formyltetrahydrofolate, a stable folate derivative, inhibits MTHFR by inducing conformational remodeling of the active site. Genetic regulation includes the common C677T polymorphism, which reduces enzyme activity and is associated with altered homocysteine levels.
methylenetetrahydrofolate reductase [NAD(P)H] activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MTHFR | Hyperhomocysteinemia, cardiovascular disease | MTHFR C677T knock-in mice |
| MTHFR | Migraine with aura | MTHFR knockout or point-mutation cell lines |
| MTHFR | Neural tube defects | MTHFR-deficient zebrafish or mouse models |
| MTHFR | Cancer chemosensitivity | Cancer cell lines with MTHFR overexpression or knockout |
| MTHFR | Folate metabolism disorders | Patient-derived iPSCs with MTHFR mutations |
Cardiovascular Disease and Hyperhomocysteinemia
Reduced MTHFR activity leads to decreased 5-methyltetrahydrofolate production, impairing homocysteine remethylation and causing hyperhomocysteinemia, a risk factor for vascular disease. The C677T polymorphism, which encodes a thermolabile enzyme with reduced activity, is a candidate genetic risk factor for cardiovascular disease.
Migraine
A meta-analysis found that the MTHFR C677T polymorphism is associated with increased migraine risk, particularly migraine with aura. This link may be mediated by elevated homocysteine levels and altered folate metabolism.
Cancer and Chemotherapy
MTHFR activity influences folate pools required for DNA synthesis and methylation, and altered activity has been implicated in cancer risk and response to antifolate drugs. Inhibitors like 5-formyltetrahydrofolate that target MTHFR may modulate chemosensitivity.
Neural Tube Defects
Impaired MTHFR activity and subsequent low folate status are associated with neural tube defects, although the exact mechanisms remain under investigation.
From methylenetetrahydrofolate reductase [NAD(P)H] activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of MTHFR loss on homocysteine levels? | MTHFR knockout cell lines or mice |
| How does the C677T polymorphism affect enzyme activity? | Point-mutation knock-in of C677T in cell lines |
| Does MTHFR overexpression alter folate pool distribution? | MTHFR overexpression cell lines |
| How does 5-formyltetrahydrofolate inhibit MTHFR? | Tagged knock-in for structural studies |
| What is the role of MTHFR in neural tube development? | MTHFR knockout zebrafish or mouse embryos |
| Can MTHFR activity be modulated by SAM analogues? | Cell lines with inducible MTHFR expression |
How to Study the methylenetetrahydrofolate reductase [NAD(P)H] activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Spectrophotometric assay | NAD(P)H oxidation at 340 nm | Enzyme kinetics and inhibitor screening |
| X-ray crystallography | Three-dimensional structure | Active-site mapping and inhibitor design |
| PCR-RFLP | C677T genotype | Clinical association studies |
| LC-MS/MS metabolomics | Folate and homocysteine levels | Metabolic phenotyping |
| Western blot | MTHFR protein expression | Validation of knockout or overexpression |
| CRISPR screening | Gene essentiality and synthetic lethality | Identifying modifiers of MTHFR activity |
| Ribo-seq | Translation efficiency | Assessing MTHFR mRNA translation under stress |
| Proteomics | Protein interactions | Identifying MTHFR binding partners |
Enzymatic Activity Assays
MTHFR activity is typically measured spectrophotometrically by monitoring the NAD(P)H-dependent conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate at 340 nm. This assay is used to characterize wild-type and mutant enzymes, including the C677T variant.
Structural Biology
X-ray crystallography and cryo-EM have been used to determine the structure of bacterial MTHFRs, revealing the active site and conformational changes upon inhibitor binding. These studies inform mechanism-based drug design.
Genotyping and Polymorphism Analysis
PCR-RFLP and TaqMan assays are commonly used to genotype the MTHFR C677T polymorphism in clinical and epidemiological studies. These methods link genotype to enzyme activity and disease risk.
Metabolomics and Flux Analysis
LC-MS/MS-based metabolomics quantifies folate species and homocysteine in cells and tissues, providing a readout of MTHFR activity in vivo. Stable isotope tracers can measure one-carbon flux.
How CRISPR Can Be Used to Study GO:0004489 methylenetetrahydrofolate reductase [NAD(P)H] activity
Knockout
CRISPR-Cas9 knockout of MTHFR in cell lines abolishes GO:0004489 activity, leading to intracellular folate pool imbalances and elevated homocysteine. These models are used to study the metabolic consequences of MTHFR loss and to identify compensatory pathways.
Point Mutation
Knock-in of the C677T point mutation using CRISPR homology-directed repair recapitulates the reduced enzyme activity seen in humans. Such models are valuable for testing the impact of the polymorphism on drug response and disease risk.
Knock-in
Tagged knock-in of MTHFR with fluorescent or affinity tags enables live-cell imaging and proteomic analysis of the enzyme. This approach helps track MTHFR localization and interactions under different metabolic conditions.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression of MTHFR increases 5-methyltetrahydrofolate production and lowers homocysteine. These models are used to study the effects of enhanced MTHFR activity on methylation and cell proliferation.
How EDITGENE Supports methylenetetrahydrofolate reductase [NAD(P)H] activity Research
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Frequently Asked Questions About methylenetetrahydrofolate reductase [NAD(P)H] activity
What is methylenetetrahydrofolate reductase [NAD(P)H] activity?
It is the enzymatic activity defined by GO:0004489 that converts 5-methyltetrahydrofolate to 5,10-methylenetetrahydrofolate using NAD(P)+ as an electron acceptor.
What genes are involved in methylenetetrahydrofolate reductase [NAD(P)H] activity?
The primary gene is MTHFR, which encodes the enzyme. Other genes in the pathway include MTR, MTRR, CBS, and SHMT1.
What is the function of MTHFR in folate metabolism?
MTHFR catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the primary methyl donor for homocysteine remethylation.
How is MTHFR activity regulated?
MTHFR is inhibited by S-adenosylmethionine and 5-formyltetrahydrofolate, and modulated by dihydrofolate polyglutamates.
What diseases are associated with MTHFR mutations?
MTHFR mutations, such as C677T, are associated with hyperhomocysteinemia, cardiovascular disease, and migraine.
What is the C677T polymorphism in MTHFR?
It is a common genetic variant that reduces MTHFR enzyme activity and is a candidate risk factor for vascular disease.
How can I study MTHFR activity in the lab?
Common methods include spectrophotometric enzyme assays, genotyping, and metabolomics.
What model systems are used for MTHFR research?
Cell lines with CRISPR knockout or knock-in of MTHFR, as well as mouse models, are widely used.
Does MTHFR have other enzymatic activities?
Yes, pig liver MTHFR exhibits dihydropterin reductase activity, indicating broader redox capabilities.
What is the role of FAD in MTHFR activity?
FAD is a cofactor that accepts electrons from NAD(P)H and transfers them to the folate substrate.
Conclusion
GO:0004489, methylenetetrahydrofolate reductase [NAD(P)H] activity, is a critical enzymatic function in one-carbon metabolism with far-reaching implications for human health. Its regulation by SAM and folate derivatives, its genetic variation, and its links to cardiovascular disease and migraine make it a compelling target for research. CRISPR-based models offer powerful tools to dissect its mechanism and role in disease.
References
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- 2. Frosst P et al.. 1995. A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase.. Nat Genet 10(1):111-3 PMID: 7647779
- 3. Yamada K et al.. 2023. 5-Formyltetrahydrofolate promotes conformational remodeling in a methylenetetrahydrofolate reductase active site and inhibits its activity.. J Biol Chem 299(2):102855 PMID: 36592927
- 4. Matthews RG et al.. 1982. Modulation of methylenetetrahydrofolate reductase activity by S-adenosylmethionine and by dihydrofolate and its polyglutamate analogues.. Adv Enzyme Regul 20:123-31 PMID: 7051769
- 5. Pantong W et al.. 2023. Biochemical and structural characterization of meningococcal methylenetetrahydrofolate reductase.. Protein Sci 32(6):e4654 PMID: 37165541
- 6. Matthews RG et al.. 1980. Characterization of the dihydropterin reductase activity of pig liver methylenetetrahydrofolate reductase.. J Biol Chem 255(13):6014-7 PMID: 6967065
- 7. Liu R et al.. 2014. MTHFR C677T polymorphism and migraine risk: a meta-analysis.. J Neurol Sci 336(1-2):68-73 PMID: 24183284
- 8. Yi J et al.. 2021. A Heterodimeric Reduced-Ferredoxin-Dependent Methylenetetrahydrofolate Reductase from Syngas-Fermenting Clostridium ljungdahlii.. Microbiol Spectr 9(2):e0095821 PMID: 34643446
