GO:0046655 folic acid metabolic process: One-Carbon Metabolism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0046655 (folic acid metabolic process) describes the chemical reactions and pathways involving folic acid (pteroylglutamic acid), a vitamin B complex member essential for purine and pyrimidine synthesis.
• Folic acid is a synthetic oxidized folate that must be reduced and methylated to enter the active one-carbon pool, with L-5-methyltetrahydrofolate being the predominant circulating form.
• The pathway supplies one-carbon units for nucleotide biosynthesis, amino acid interconversion, and methylation reactions, making it indispensable for cell proliferation.
• Genetic polymorphisms in folate-metabolizing enzymes alter folate status and influence disease susceptibility, including neural tube defects and cancer.
• Folate metabolism is compartmentalized between cytosol and mitochondria, and mitochondrial folate cycle enzymes are emerging as regulators of purine synthesis and redox balance.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) enable causal interrogation of folate pathway genes in health and disease.
Description
Folic acid metabolic process (GO:0046655) encompasses the chemical reactions and pathways involving folic acid, also known as pteroylglutamic acid, a member of the vitamin B complex. This process is fundamental to one-carbon metabolism, providing the essential cofactors required for the de novo synthesis of purines and pyrimidines, as well as for amino acid interconversion and methylation reactions. Because rapidly dividing cells depend on folate-dependent nucleotide synthesis, perturbations in this pathway have profound effects on cell proliferation, development, and genome stability. Folic acid itself is a synthetic, fully oxidized form of the vitamin that does not occur naturally in significant amounts in human tissues; it must be reduced to dihydrofolate and then to tetrahydrofolate, and subsequently converted to one-carbon derivatives such as 10-formyltetrahydrofolate, 5,10-methylenetetrahydrofolate, and 5-methyltetrahydrofolate. These derivatives serve as donors and acceptors in a network of interconnected reactions that shuttle one-carbon units between the cytosol, mitochondria, and nucleus. The clinical importance of this pathway is underscored by the widespread use of folic acid supplementation to prevent neural tube defects and by the association of folate-related polymorphisms with cancer risk and other diseases. For researchers, GO:0046655 provides a structured framework to study how genetic and environmental factors influence folate homeostasis and how disruptions contribute to human pathology. Understanding the molecular players, regulatory mechanisms, and experimental models available to interrogate this process is essential for advancing both basic biology and therapeutic development.
folic acid metabolic process At A Glance
| GO ID | GO:0046655 |
|---|---|
| GO term | folic acid metabolic process |
| Ontology | biological_process |
| Synonym | folate metabolic process; folate metabolism; folic acid metabolism; vitamin B9 metabolic process; vitamin B9 metabolism; vitamin M metabolic process; vitamin M metabolism |
| Major function | One-carbon metabolism for purine and pyrimidine synthesis, amino acid interconversion, and methylation reactions |
| Key substrates | Folic acid, dihydrofolate, tetrahydrofolate, 5,10-methylenetetrahydrofolate, 5-methyltetrahydrofolate, 10-formyltetrahydrofolate |
| Cellular compartments | Cytosol, mitochondria, nucleus |
| Related cofactors | NADPH, NADH, FAD, PLP, vitamin B12 |
| Clinical relevance | Neural tube defects, cancer, cardiovascular disease, and antifolate drug response |
What Is GO:0046655?
In our own words, GO:0046655 (folic acid metabolic process) refers to the sum of biochemical reactions and pathways that convert, interconvert, and utilize folic acid (pteroylglutamic acid) and its derivatives. This includes the reduction of folic acid to dihydrofolate and tetrahydrofolate, the generation of one-carbon substituted tetrahydrofolates, and the transfer of one-carbon units for the synthesis of purines, pyrimidines, and methionine, as well as for methylation reactions. The term is synonymous with folate metabolic process, folate metabolism, folic acid metabolism, vitamin B9 metabolic process, vitamin B9 metabolism, vitamin M metabolic process, and vitamin M metabolism.
Why Is folic acid metabolic process Important in Cell Biology?
Folic acid metabolic process is central to cellular one-carbon metabolism, which supports nucleotide biosynthesis, amino acid homeostasis, and methylation reactions essential for gene regulation and genome maintenance. Because folate deficiency or genetic variation in folate pathway enzymes can impair DNA synthesis and repair, this process is directly linked to developmental disorders, cancer predisposition, and therapeutic responses to antifolate drugs. Moreover, recent studies have revealed that mitochondrial folate enzymes contribute to redox balance and lipogenesis, expanding the importance of this pathway beyond nucleotide synthesis.
• Provides one-carbon units for de novo purine and pyrimidine synthesis, critical for DNA replication and cell division.
• Supports methionine synthesis and the methylation cycle, influencing epigenetic regulation.
• Genetic polymorphisms in folate-metabolizing genes (e.g., MTHFR, MTR, MTHFD1) affect folate status and disease risk.
• Folate deficiency is associated with neural tube defects and megaloblastic anemia.
• Antifolate drugs (e.g., methotrexate) target folate metabolism in cancer and autoimmune diseases.
• Mitochondrial folate cycle enzymes regulate redox homeostasis and lipogenesis.
• Succinylation of mitochondrial folate enzymes links metabolic stress to purine synthesis.
• Folic acid supplementation is a public health strategy to prevent birth defects.
• Folate status biomarkers are used clinically to assess nutritional and disease states.
• CRISPR screens can identify synthetic lethal interactions with folate pathway inhibition.
What Happens During folic acid metabolic process?
Absorption and transport of folic acid
In simple terms: Folic acid from diet or supplements is taken up by cells and converted into active forms.
Folic acid is absorbed in the small intestine and transported into cells via reduced folate carriers and folate receptors. Inside cells, it must be reduced to dihydrofolate and then to tetrahydrofolate by dihydrofolate reductase (DHFR) before it can enter the one-carbon pool. The synthetic form folic acid is not naturally found in human tissues and requires this activation step, whereas natural folates are already reduced.
One-carbon unit generation and interconversion
In simple terms: Tetrahydrofolate picks up and carries one-carbon units in different chemical forms.
Tetrahydrofolate (THF) serves as the central acceptor and donor of one-carbon units. Serine hydroxymethyltransferase (SHMT) converts serine to glycine, transferring a one-carbon unit to THF to form 5,10-methylenetetrahydrofolate (5,10-methylene-THF). This can be reduced to 5-methyltetrahydrofolate (5-methyl-THF) by methylenetetrahydrofolate reductase (MTHFR) or oxidized to 10-formyltetrahydrofolate (10-formyl-THF) via the bifunctional enzyme MTHFD1/2. These interconversions are compartmentalized between cytosol and mitochondria.
Purine and pyrimidine synthesis
In simple terms: Folate derivatives provide the building blocks for DNA and RNA.
10-formyl-THF donates two carbons to the purine ring during de novo purine synthesis, while 5,10-methylene-THF provides the methyl group for thymidylate synthesis via thymidylate synthase (TYMS). Inhibition of these reactions blocks DNA replication and cell proliferation, which is the basis for antifolate chemotherapy. Recent work shows that mitochondrial folate cycle enzymes, including MTHFD2, are required for purine synthesis and that their succinylation can suppress this pathway.
Methionine synthesis and methylation cycle
In simple terms: Folate helps regenerate methionine, which is needed for methylation reactions.
5-methyl-THF donates its methyl group to homocysteine to form methionine, a reaction catalyzed by methionine synthase (MTR) with vitamin B12 as a cofactor. Methionine is then converted to S-adenosylmethionine (SAM), the universal methyl donor for DNA, RNA, protein, and lipid methylation. This links folate metabolism to epigenetic regulation and to the methionine cycle.
Mitochondrial folate cycle and redox balance
In simple terms: Mitochondria use folate enzymes to produce energy and maintain redox balance.
The mitochondrial folate cycle, involving MTHFD2, MTHFD2L, and SHMT2, generates one-carbon units and contributes to NADPH production. Serine catabolism in mitochondria generates liver NADPH and supports hepatic lipogenesis. Additionally, accumulation of succinate can suppress de novo purine synthesis through succinylation-mediated control of the mitochondrial folate cycle, linking metabolic stress to folate-dependent nucleotide synthesis.
Key Genes Involved in GO:0046655 folic acid metabolic process
The following genes encode enzymes and transporters that are directly involved in folic acid metabolic process (GO:0046655) and are commonly studied in research and clinical contexts.
| Gene | Major Role | Research Relevance |
|---|---|---|
| DHFR | Reduces dihydrofolate to tetrahydrofolate | Target of methotrexate; essential for folate activation |
| MTHFR | Reduces 5,10-methylene-THF to 5-methyl-THF | Common polymorphisms affect folate status and disease risk |
| MTR | Methionine synthase; transfers methyl from 5-methyl-THF to homocysteine | Links folate to methylation cycle; vitamin B12 dependent |
| MTHFD1 | Bifunctional methylenetetrahydrofolate dehydrogenase/cyclohydrolase | Provides one-carbon units for purine synthesis |
| MTHFD2 | Mitochondrial methylenetetrahydrofolate dehydrogenase | Supports purine synthesis; succinylation regulates activity |
| SHMT1 | Cytosolic serine hydroxymethyltransferase | Generates 5,10-methylene-THF from serine |
| SHMT2 | Mitochondrial serine hydroxymethyltransferase | Supports mitochondrial one-carbon metabolism and NADPH production |
| TYMS | Thymidylate synthase; synthesizes dTMP from dUMP | Target of 5-fluorouracil; requires 5,10-methylene-THF |
| GART | Phosphoribosylglycinamide formyltransferase; purine synthesis | Uses 10-formyl-THF for purine ring |
| ATIC | Bifunctional purine biosynthesis protein; uses 10-formyl-THF | Involved in purine synthesis and antifolate response |
| SLC19A1 | Reduced folate carrier; transports folates into cells | Determines cellular folate uptake |
| FOLR1 | Folate receptor alpha; mediates folate transport | Target for folate-conjugated therapeutics |
| MTHFS | Methenyltetrahydrofolate synthetase | Regulates 10-formyl-THF levels |
| ALDH1L1 | 10-formyltetrahydrofolate dehydrogenase | Regulates one-carbon pool and NADPH production |
| MTRR | Methionine synthase reductase | Maintains MTR activity; affects folate status |
| CBS | Cystathionine beta-synthase; transsulfuration | Links folate cycle to homocysteine metabolism |
| MTHFD1L | Mitochondrial 10-formyl-THF synthetase | Generates formate for cytosolic one-carbon pool |
How Is folic acid metabolic process Regulated?
Folic acid metabolic process is regulated at multiple levels. Enzyme expression is controlled by transcription factors responsive to nutrient status, and allosteric regulation by SAM and dihydrofolate polyglutamation modulates flux. The methionine cycle and folate cycle are reciprocally regulated through SAM-dependent inhibition of MTHFR and activation of cystathionine beta-synthase. Recent evidence indicates that post-translational modifications, such as succinylation of mitochondrial folate enzymes, can suppress de novo purine synthesis under metabolic stress. Additionally, serine catabolism in mitochondria generates NADPH and supports hepatic lipogenesis, linking folate metabolism to cellular redox and energy status.
folic acid metabolic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| MTHFR | Neural tube defects, cardiovascular disease | Knock-in of C677T polymorphism in cell lines |
| DHFR | Cancer, antifolate drug resistance | Knockout and point mutation for methotrexate resistance |
| MTHFD2 | Cancer, metabolic stress | Knockout and succinylation-site point mutation |
| SHMT2 | Metabolic disease, lipogenesis | Liver-specific knockout and overexpression |
| TYMS | Cancer, 5-fluorouracil response | Knockout and overexpression for drug sensitivity |
Folate deficiency and neural tube defects
Inadequate folate status during early pregnancy is a well-established risk factor for neural tube defects (NTDs), and periconceptional folic acid supplementation significantly reduces NTD incidence. Genetic polymorphisms in folate-metabolizing genes, particularly MTHFR C677T, further modulate risk by altering enzyme activity and folate distribution.
Cancer and antifolate therapy
Folate metabolism is a validated target in oncology because rapidly proliferating cancer cells depend on one-carbon units for nucleotide synthesis. Methotrexate and pemetrexed inhibit DHFR and other folate enzymes, while 5-fluorouracil targets thymidylate synthase. Polymorphisms in MTHFR and TYMS influence drug response and toxicity.
Cardiovascular disease and hyperhomocysteinemia
Impaired folate metabolism can lead to elevated homocysteine levels, a risk factor for cardiovascular disease. MTHFR polymorphisms and low folate status are associated with hyperhomocysteinemia, and folate supplementation lowers homocysteine.
Mitochondrial folate cycle in metabolic disease
Emerging evidence links mitochondrial folate enzymes to metabolic regulation. Serine catabolism via SHMT2 and MTHFD2 generates NADPH and supports lipogenesis in the liver. Succinate accumulation can suppress purine synthesis through succinylation of mitochondrial folate enzymes, connecting metabolic stress to nucleotide imbalance.
From folic acid metabolic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of DHFR impair folate-dependent nucleotide synthesis? | DHFR knockout cell line |
| Does the MTHFR C677T polymorphism alter folate distribution? | MTHFR C677T knock-in cell line |
| Does succinylation of MTHFD2 regulate purine synthesis? | MTHFD2 succinylation-site point mutation |
| Does SHMT2 overexpression increase NADPH production? | SHMT2 overexpression cell line |
| Can tagged MTHFD2 reveal mitochondrial localization dynamics? | Tagged knock-in of MTHFD2 |
| Which genes are synthetic lethal with methotrexate? | CRISPR library screening in folate pathway mutants |
How to Study the folic acid metabolic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| LC-MS metabolomics | Folate species and one-carbon metabolites | Quantifying pathway activity |
| Stable isotope tracing | Flux through folate cycle | Assessing serine/formate utilization |
| RNA-seq | Gene expression changes | Identifying folate pathway regulation |
| CRISPR knockout screening | Gene essentiality and drug resistance | Discovering synthetic lethal interactions |
| Enzyme activity assay | DHFR, MTHFR, TYMS activity | Functional validation of variants |
| Western blot | Protein expression and modifications | Detecting succinylation or phosphorylation |
| Immunofluorescence | Subcellular localization | Visualizing mitochondrial folate enzymes |
| Genotyping | SNP detection (e.g., MTHFR C677T) | Associating polymorphisms with disease |
Metabolomics and one-carbon flux analysis
Liquid chromatography-mass spectrometry (LC-MS) can quantify folate species and one-carbon metabolites to assess pathway activity. Stable isotope tracing with 13C-serine or 13C-formate enables flux analysis through the folate cycle.
Genomic and transcriptomic profiling
RNA-seq and targeted sequencing can identify expression changes and polymorphisms in folate pathway genes. GWAS and candidate-gene studies have linked MTHFR, MTR, and MTHFD1 variants to folate status and disease risk.
CRISPR screening and functional genomics
Genome-wide CRISPR knockout screens can identify genes that are essential in folate-limited conditions or that mediate resistance to antifolates. Such screens have revealed metabolic vulnerabilities linked to mitochondrial folate enzymes.
Enzyme activity assays and protein analysis
Enzymatic assays measure DHFR, MTHFR, and TYMS activities in cell lysates. Western blotting and immunoprecipitation can assess protein levels and post-translational modifications such as succinylation.
How CRISPR Can Be Used to Study GO:0046655 folic acid metabolic process
Knockout
CRISPR knockout of folate pathway genes such as DHFR, MTHFR, or MTHFD2 can reveal their essentiality for cell proliferation and nucleotide synthesis. Knockout models are valuable for identifying metabolic vulnerabilities and for validating drug targets.
Point Mutation
Introducing disease-associated point mutations, such as MTHFR C677T or succinylation-site mutations in MTHFD2, allows precise interrogation of how specific amino acid changes alter enzyme activity and pathway flux.
Knock-in
Knock-in of tagged versions of folate enzymes (e.g., GFP-MTHFD2) enables live-cell imaging and proteomic analysis of localization and interactions. Knock-in of polymorphic variants can model human genetic diversity.
Overexpression
Overexpression of genes like SHMT2 or MTHFD2 can mimic metabolic states in cancer or metabolic disease, allowing researchers to study effects on NADPH production, lipogenesis, and purine synthesis.
How EDITGENE Supports folic acid metabolic process Research
Researchers studying folic acid metabolic process-related genes often need to determine whether a candidate gene is causally involved in pathway regulation, disease risk, or drug response. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models that enable such causal inferences.
Contact EDITGENE today to design your custom CRISPR model for folic acid metabolic process research.
Frequently Asked Questions About folic acid metabolic process
What is folic acid metabolic process (GO:0046655)?
It is the set of biochemical reactions and pathways involving folic acid (pteroylglutamic acid), essential for purine and pyrimidine synthesis and one-carbon metabolism.
What genes are involved in folic acid metabolic process?
Key genes include DHFR, MTHFR, MTR, MTHFD1, MTHFD2, SHMT1, SHMT2, TYMS, and SLC19A1, among others.
Why is folic acid important for DNA synthesis?
Folic acid derivatives provide one-carbon units for de novo purine and thymidylate synthesis, which are required for DNA replication.
What diseases are linked to folate metabolism defects?
Neural tube defects, cancer, cardiovascular disease, and hyperhomocysteinemia are associated with impaired folate metabolism.
How is folic acid metabolized in cells?
Folic acid is reduced to dihydrofolate and tetrahydrofolate, then converted to one-carbon derivatives like 5,10-methylene-THF and 5-methyl-THF.
What is the role of MTHFR in folate metabolism?
MTHFR reduces 5,10-methylene-THF to 5-methyl-THF, which is used for methionine synthesis; polymorphisms affect folate status.
Can CRISPR be used to study folate metabolism?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable causal studies of folate pathway genes.
What is the difference between folic acid and folate?
Folic acid is the synthetic oxidized form used in supplements, while folate refers to natural reduced forms found in food.
How does the mitochondrial folate cycle contribute to metabolism?
It generates one-carbon units and NADPH, supports lipogenesis, and can be regulated by succinylation.
What experimental methods are used to study folate metabolism?
LC-MS metabolomics, stable isotope tracing, RNA-seq, CRISPR screens, and enzyme activity assays are commonly used.
Conclusion
Folic acid metabolic process (GO:0046655) is a cornerstone of one-carbon metabolism, supplying essential building blocks for nucleotide synthesis, methylation, and redox balance. Its dysfunction is implicated in a wide range of human diseases, from neural tube defects to cancer and cardiovascular disease. Advances in CRISPR-based models and metabolomic technologies are enabling precise interrogation of this pathway, offering new opportunities for therapeutic intervention. EDITGENE provides the tools and expertise to accelerate research in this vital area.
References
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