GO:0004047 aminomethyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0004047 aminomethyltransferase activity catalyzes the transfer of an aminomethyl group from a lipoyl-bound intermediate to tetrahydrofolate, releasing ammonia and producing 5,10-methylene-THF.
• The enzyme, historically called T-protein, is the third component of the glycine cleavage system and is essential for glycine and one-carbon metabolism.
• Biallelic mutations in AMT cause nonketotic hyperglycinemia, a severe neurometabolic disorder with elevated glycine in blood and cerebrospinal fluid.
• The crystal structure of T-protein in complex with the H-protein reveals the molecular basis for substrate recognition and disease-related mutations.
• Aminomethyltransferase activity is conserved from bacteria to humans, and in some parasites such as Plasmodium berghei the T-protein is non-essential for survival.
• Studying GO:0004047 requires integrating structural biology, enzymology, and CRISPR-based cellular models to dissect its role in health and disease.
Description
Aminomethyltransferase activity (GO:0004047) is a molecular function that catalyzes a key step in the glycine cleavage system, a multienzyme complex responsible for the oxidative decarboxylation of glycine. This activity transfers an aminomethyl group from a lipoyl-bound intermediate to tetrahydrofolate, generating 5,10-methylene-tetrahydrofolate and ammonia. The reaction is essential for one-carbon metabolism, which supports nucleotide synthesis, methylation reactions, and redox homeostasis. In humans, the enzyme is encoded by the AMT gene, and its dysfunction leads to nonketotic hyperglycinemia, a devastating neurological disorder. Understanding GO:0004047 is therefore critical for researchers studying metabolic diseases, enzyme mechanisms, and potential therapeutic interventions.
aminomethyltransferase activity At A Glance
| GO ID | GO:0004047 |
|---|---|
| GO term | aminomethyltransferase activity |
| Ontology | molecular_function |
| Synonym | glycine-cleavage system T-protein activity; glycine synthase activity; T-protein |
| Major function | Catalyzes the transfer of an aminomethyl group from a lipoyl-bound intermediate to tetrahydrofolate, producing 5,10-methylene-THF and ammonia. |
| EC number | 2.1.2.10 |
| Reaction participants | N(6)-[(R)-S(8)-aminomethyldihydrolipoyl]-L-lysyl-[protein], (6S)-5,6,7,8-tetrahydrofolate, N(6)-[(R)-dihydrolipoyl]-L-lysyl-[protein], (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate, NH4+. |
| Pathway context | Glycine cleavage system, one-carbon metabolism. |
| Human gene | AMT (aminomethyltransferase). |
What Is GO:0004047?
According to the Gene Ontology, GO:0004047 aminomethyltransferase activity is defined as the catalysis of the reaction: N(6)-[(R)-S(8)-aminomethyldihydrolipoyl]-L-lysyl-[protein] + (6S)-5,6,7,8-tetrahydrofolate = N(6)-[(R)-dihydrolipoyl]-L-lysyl-[protein] + (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate + NH4+. In simpler terms, it is the enzyme activity that removes an aminomethyl group from a modified lipoyl protein and transfers it to tetrahydrofolate, releasing ammonia and forming methylene-tetrahydrofolate.
Why Is aminomethyltransferase activity Important in Cell Biology?
Aminomethyltransferase activity is a central node in one-carbon metabolism, linking glycine catabolism to the folate cycle. This connection is vital for supplying methylene-tetrahydrofolate for thymidylate and purine synthesis, as well as for methylation reactions. In humans, loss-of-function mutations in AMT cause nonketotic hyperglycinemia, characterized by severe neurological impairment, seizures, and developmental delay. The enzyme is also a target for understanding metabolic reprogramming in cancer and for studying host-pathogen interactions, as some parasites rely on or tolerate its absence. Thus, GO:0004047 is of broad interest to biochemists, geneticists, and clinicians.
• Essential for glycine cleavage and one-carbon metabolism.
• Mutations cause nonketotic hyperglycinemia, a severe neurometabolic disorder.
• Provides 5,10-methylene-THF for nucleotide biosynthesis and methylation.
• Conserved across species, from bacteria to humans.
• In Plasmodium berghei, T-protein is non-essential for survival, highlighting metabolic flexibility.
• Structural studies reveal drug-targetable interfaces and disease mechanisms.
• Potential role in cancer metabolism and epigenetic regulation.
• Model for studying enzyme evolution and folate-dependent reactions.
• Relevant to newborn screening and genetic counseling.
• Enables CRISPR-based functional genomics of metabolic pathways.
What Happens During aminomethyltransferase activity?
Step 1: Formation of the aminomethyl-lipoyl intermediate
In simple terms: First, a glycine molecule is broken down and its aminomethyl group gets attached to a carrier protein.
The glycine cleavage system begins with the decarboxylation of glycine by the P-protein, transferring the remaining aminomethyl group to the lipoyl moiety of the H-protein, forming an aminomethyl-dihydrolipoyl intermediate.
Step 2: Substrate recognition by T-protein
In simple terms: The T-protein enzyme recognizes and binds the modified carrier protein.
Aminomethyltransferase (T-protein) specifically binds the aminomethyl-dihydrolipoyl-H-protein complex, as revealed by the crystal structure of the T-protein in complex with dihydrolipoyl-H-protein. This interaction positions the substrate for catalysis.
Step 3: Transfer of the aminomethyl group to tetrahydrofolate
In simple terms: The enzyme moves the aminomethyl group onto a folate molecule.
The aminomethyl group is transferred from the lipoyl intermediate to (6S)-5,6,7,8-tetrahydrofolate, producing (6R)-5,10-methylene-5,6,7,8-tetrahydrofolate and releasing ammonia. This reaction is the defining catalytic step of GO:0004047.
Step 4: Regeneration of the lipoyl carrier
In simple terms: The carrier protein is restored to its original state to participate again.
The dihydrolipoyl-H-protein is reoxidized by the L-protein (dihydrolipoamide dehydrogenase) to regenerate the lipoyl-H-protein, allowing the cycle to continue.
Key Genes Involved in GO:0004047 aminomethyltransferase activity
The following genes and proteins are directly or functionally associated with aminomethyltransferase activity (GO:0004047) and the glycine cleavage system.
| Gene | Major Role | Research Relevance |
|---|---|---|
| AMT | Encodes aminomethyltransferase (T-protein); catalyzes the transfer of aminomethyl group to THF. | Mutations cause nonketotic hyperglycinemia; target for structural and functional studies. |
| GLDC | Encodes glycine decarboxylase (P-protein); forms the aminomethyl-lipoyl intermediate. | Mutations also cause nonketotic hyperglycinemia; interacts with AMT. |
| GCSH | Encodes H-protein; carries lipoyl group and shuttles intermediates. | Essential for T-protein substrate recognition; studied in complex with AMT. |
| DLD | Encodes dihydrolipoamide dehydrogenase (L-protein); reoxidizes H-protein. | Defects cause E3 deficiency; relevant to glycine cleavage system. |
| MTHFD1 | Provides 5,10-methylene-THF for folate cycle. | Links one-carbon metabolism to nucleotide synthesis. |
| MTHFR | Regenerates 5-methyl-THF for methionine synthesis. | Interacts with glycine cleavage pathway. |
| SHMT1 | Serine hydroxymethyltransferase; interconverts serine and glycine. | Contributes to one-carbon pools. |
| SHMT2 | Mitochondrial serine hydroxymethyltransferase; produces glycine. | Supplies glycine for cleavage system. |
| GATM | Glycine amidinotransferase; consumes glycine. | Competes with glycine cleavage. |
| SLC6A9 | Glycine transporter; regulates glycine levels. | Affects substrate availability for GCS. |
| GLYT1 | Glycine transporter; modulates synaptic glycine. | Relevant to hyperglycinemia neuropathology. |
| GLYT2 | Glycine transporter; regulates glycine in brainstem. | Potential modifier of NKH. |
| YgfZ | Folate-dependent regulatory protein in E. coli; may interact with one-carbon metabolism. | Model for folate-dependent regulation. |
| PbGCS-T | Plasmodium berghei T-protein; non-essential for parasite survival. | Studied for parasite metabolism. |
| AMT (bacterial) | Bacterial aminomethyltransferase; homolog of human enzyme. | Used for structural and mechanistic studies. |
| GCSH (bacterial) | Bacterial H-protein; substrate for T-protein. | Crystallized in complex with T-protein. |
How Is aminomethyltransferase activity Regulated?
Aminomethyltransferase activity is regulated at multiple levels. Transcriptionally, the AMT gene may be influenced by metabolic demands, though specific transcription factors are not fully defined. Post-translationally, the glycine cleavage system is sensitive to the redox state and availability of its substrates and cofactors, including lipoate and tetrahydrofolate. The activity of the complex can be modulated by the NAD+/NADH ratio through the L-protein. Additionally, folate status affects the reaction rate, as tetrahydrofolate is a direct substrate. In some organisms, such as Plasmodium berghei, the T-protein is dispensable, suggesting alternative metabolic routes.
aminomethyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| AMT | Nonketotic hyperglycinemia | Patient-derived fibroblasts; AmT knockout mouse |
| GLDC | Nonketotic hyperglycinemia | Gldc knockout mouse |
| GCSH | Nonketotic hyperglycinemia (rare) | Gcsh knockout cell lines |
| DLD | E3 deficiency with glycine elevation | Dld knockout models |
| PbGCS-T | Parasite survival | Plasmodium berghei knockout |
Nonketotic hyperglycinemia (NKH)
Biallelic pathogenic variants in AMT cause nonketotic hyperglycinemia, an autosomal recessive disorder characterized by accumulation of glycine in body fluids and severe neurological symptoms, including seizures, hypotonia, and developmental delay. A synonymous variant in AMT has been reported to cause severe NKH, highlighting the importance of non-coding mutations.
Cancer metabolism
Altered one-carbon metabolism, including glycine cleavage, is observed in various cancers. The enzyme may contribute to metabolic reprogramming by supplying methylene-THF for nucleotide synthesis. However, direct evidence linking AMT mutations to cancer is limited.
Infectious disease
In Plasmodium berghei, the T-protein of the glycine cleavage system is non-essential for survival in vertebrate and invertebrate hosts, suggesting that the parasite can bypass this metabolic step. This raises questions about the role of aminomethyltransferase in pathogen metabolism and potential drug targeting.
From aminomethyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Enzyme catalytic mechanism | Recombinant T-protein and H-protein for crystallography |
| Loss-of-function in human cells | AMT knockout HEK293 or HeLa cells |
| Disease-causing point mutations | Knock-in of patient variants (e.g., synonymous variant) |
| Subcellular localization | Tagged knock-in of AMT with GFP |
| Metabolic flux | Overexpression of AMT in cancer cell lines |
| Parasite metabolism | Plasmodium berghei T-protein knockout |
How to Study the aminomethyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| X-ray crystallography | Three-dimensional structure of protein complexes | Mechanistic studies and drug design |
| Enzyme activity assay | Catalytic rate of aminomethyl transfer | Kinetic characterization |
| CRISPR knockout | Loss-of-function phenotype | Gene essentiality and metabolic profiling |
| CRISPR knock-in | Effect of specific mutations | Modeling patient variants |
| Metabolomics | Levels of glycine, serine, folates | Pathway flux analysis |
| Western blot | Protein expression and tagging | Validation of knockout/overexpression |
| Immunofluorescence | Subcellular localization | Mitochondrial targeting |
| RNA-seq | Transcriptional changes | Pathway adaptation |
Structural biology
X-ray crystallography of T-protein in complex with H-protein has elucidated the binding interface and catalytic residues, providing a template for understanding disease mutations.
Enzymatic assays
Aminomethyltransferase activity can be measured spectrophotometrically by coupling the release of ammonia or the formation of 5,10-methylene-THF to NADH production.
Genetic and genomic approaches
CRISPR-Cas9 knockout and knock-in models enable functional dissection of AMT and related genes in human cell lines and animal models.
Metabolomics
Mass spectrometry-based metabolomics can quantify glycine, serine, and folate species to assess pathway flux in cells with altered aminomethyltransferase activity.
How CRISPR Can Be Used to Study GO:0004047 aminomethyltransferase activity
Knockout
CRISPR-Cas9 knockout of AMT in human cell lines abolishes aminomethyltransferase activity, leading to glycine accumulation and altered one-carbon metabolism. Such models are valuable for studying NKH pathophysiology and identifying compensatory pathways.
Point Mutation
Introducing patient-specific point mutations, such as the synonymous variant linked to severe NKH, allows researchers to assess the impact on splicing, protein stability, and enzyme activity.
Knock-in
Knock-in of tagged AMT (e.g., GFP or FLAG) enables visualization of subcellular localization and interaction partners in live cells. This approach can also be used to create isogenic disease models.
Overexpression
Overexpression of wild-type or mutant AMT in cancer cell lines can reveal effects on proliferation, metabolic flux, and sensitivity to antifolates.
How EDITGENE Supports aminomethyltransferase activity Research
Researchers studying aminomethyltransferase 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 discovery process.
Contact EDITGENE today to design your custom CRISPR model for aminomethyltransferase activity research.
Frequently Asked Questions About aminomethyltransferase activity
What is aminomethyltransferase activity?
Aminomethyltransferase activity (GO:0004047) is the enzyme activity that transfers an aminomethyl group from a lipoyl-bound intermediate to tetrahydrofolate, producing 5,10-methylene-THF and ammonia.
What genes are involved in aminomethyltransferase activity?
The primary gene is AMT, which encodes the T-protein. Other genes in the glycine cleavage system include GLDC, GCSH, and DLD.
What diseases are associated with aminomethyltransferase deficiency?
Mutations in AMT cause nonketotic hyperglycinemia, a severe neurological disorder with elevated glycine levels.
What is the role of T-protein in the glycine cleavage system?
T-protein (aminomethyltransferase) catalyzes the transfer of the aminomethyl group from H-protein to tetrahydrofolate, releasing ammonia.
How is aminomethyltransferase activity measured?
It can be measured using coupled enzyme assays that detect ammonia release or the formation of 5,10-methylene-THF.
What is the structure of aminomethyltransferase?
The crystal structure of T-protein in complex with H-protein reveals a tightly bound complex with specific recognition of the lipoyl substrate.
Is aminomethyltransferase essential in all organisms?
It is essential in humans, but in Plasmodium berghei the T-protein is non-essential for survival, indicating metabolic flexibility.
What are the synonyms for aminomethyltransferase activity?
Synonyms include glycine-cleavage system T-protein activity, glycine synthase activity, and T-protein.
How can CRISPR be used to study aminomethyltransferase activity?
CRISPR knockout, knock-in, and point mutation models allow functional dissection of AMT and related genes in cells and animals.
What is the EC number for aminomethyltransferase?
The EC number is 2.1.2.10.
Conclusion
Aminomethyltransferase activity (GO:0004047) is a fundamental enzymatic function in glycine and one-carbon metabolism, with critical roles in human health and disease. Structural and genetic studies have illuminated its mechanism and link to nonketotic hyperglycinemia. Leveraging CRISPR-based models and EDITGENE services can further unravel its biology and therapeutic potential.
References
- 1. Adam MP et al.. 1993. Nonketotic Hyperglycinemia.. PMID: 20301531
- 2. Okamura-Ikeda K et al.. 2010. Crystal structure of aminomethyltransferase in complex with dihydrolipoyl-H-protein of the glycine cleavage system: implications for recognition of lipoyl protein substrate, disease-related mutations, and reaction mechanism.. J Biol Chem 285(24):18684-92 PMID: 20375021
- 3. Pang P et al.. 2025. Severe nonketotic hyperglycinaemia due to a synonymous variant.. Mol Genet Metab Rep 45:101268 PMID: 41142854
- 4. Rodriguez F et al.. 2022. Bacterial N4-methylcytosine as an epigenetic mark in eukaryotic DNA.. Nat Commun 13(1):1072 PMID: 35228526
- 5. Teplyakov A et al.. 2004. Crystal structure of the YgfZ protein from Escherichia coli suggests a folate-dependent regulatory role in one-carbon metabolism.. J Bacteriol 186(21):7134-40 PMID: 15489424
- 8. Varadarajan NM et al.. 2014. Plasmodium berghei glycine cleavage system T-protein is non-essential for parasite survival in vertebrate and invertebrate hosts.. Mol Biochem Parasitol 197(1-2):50-5 PMID: 25454081
