GO:1904047 S-adenosyl-L-methionine binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1904047 (S-adenosyl-L-methionine binding) is a molecular_function term describing the binding of S-adenosyl-L-methionine (SAM), the principal methyl donor in cells.
• SAM binding is a prerequisite for the catalytic activity of methyltransferases and many radical SAM enzymes, and interaction signatures are conserved across diverse protein folds.
• SAM-dependent enzymes include DNA methyltransferases such as DNMT3A, which can be irreversibly inhibited by SAM analogs.
• SAM binding also modulates non-methyltransferase proteins, including cystathionine beta-synthase (CBS) and the cardiac ryanodine receptor (RYR2).
• SAM and S-adenosyl-L-homocysteine (SAH) binding proteins can be profiled with capture compounds, enabling discovery of new SAM-binding proteins.
• Dysregulation of SAM-binding proteins is linked to cancer, cardiovascular disease, and metabolic disorders, making them attractive therapeutic targets.
Description
S-adenosyl-L-methionine (SAM) is the second most widely used enzyme cofactor after ATP and serves as the primary methyl group donor in biological methylation reactions. The Gene Ontology term GO:1904047, S-adenosyl-L-methionine binding, describes the molecular function of selectively interacting with SAM. This term is distinct from catalytic activity; it captures the binding event that positions SAM for subsequent chemistry or regulation. SAM-binding proteins are ubiquitous and include methyltransferases, radical SAM enzymes, and regulatory proteins that sense SAM availability. Understanding SAM binding is therefore central to epigenetics, metabolism, and drug discovery. The interaction between SAM and its protein partners is highly specific, relying on a conserved binding pocket that recognizes the adenosyl and methionine moieties. Structural and biochemical studies have revealed that SAM binding can induce conformational changes that regulate enzyme activity, as seen in human cystathionine beta-synthase and the cardiac ryanodine receptor. Moreover, SAM analogs have been developed as inhibitors of DNA methyltransferases, highlighting the therapeutic potential of targeting SAM-binding sites. This article provides a comprehensive overview of GO:1904047, covering its definition, biological significance, key genes, disease associations, and research methodologies, with a focus on CRISPR-based models for functional studies.
S-adenosyl-L-methionine binding At A Glance
| GO ID | GO:1904047 |
|---|---|
| GO term | S-adenosyl-L-methionine binding |
| Ontology | molecular_function |
| Synonym | radical SAM enzyme activity |
| Definition | Binding to S-adenosyl-L-methionine. |
| Major function | Mediates specific recognition of SAM for methylation, radical chemistry, or regulatory sensing. |
| Cofactor | S-adenosyl-L-methionine (SAM) |
| Related ligand | S-adenosyl-L-homocysteine (SAH), the demethylated product |
| Representative proteins | DNMT3A, CBS, RYR2, and many methyltransferases |
What Is GO:1904047?
GO:1904047 is defined by the Gene Ontology as the binding to S-adenosyl-L-methionine. In other words, it is the molecular function of a protein or RNA molecule that selectively and non-covalently interacts with SAM. This term is used to annotate gene products that physically associate with SAM, regardless of whether the binding leads to catalysis. It is a child of the broader term 'binding' and is distinct from 'S-adenosylmethionine-dependent methyltransferase activity', which requires catalysis. The synonym 'radical SAM enzyme activity' reflects the historical association of this binding term with radical SAM enzymes, though the term itself is not limited to them.
Why Is S-adenosyl-L-methionine binding Important in Cell Biology?
SAM binding is a fundamental molecular event that underpins methylation reactions, epigenetic regulation, and metabolic sensing. Because SAM is the universal methyl donor, proteins that bind SAM control DNA, RNA, protein, and metabolite methylation, influencing gene expression, genome stability, and cellular signaling. Dysregulated SAM binding can lead to aberrant methylation patterns associated with cancer, cardiovascular disease, and neurological disorders. Furthermore, SAM-binding proteins are promising drug targets, as exemplified by SAM-competitive inhibitors of DNMT3A. Studying GO:1904047 therefore provides mechanistic insights into normal physiology and disease, and guides the development of precision therapeutics.
• SAM binding is required for the catalytic activity of DNA methyltransferases such as DNMT3A, which are frequently dysregulated in cancer.
• SAM binding modulates the activity of cystathionine beta-synthase (CBS), affecting hydrogen sulfide and homocysteine metabolism.
• SAM binding to the cardiac ryanodine receptor (RYR2) activates calcium release, linking SAM to cardiac function.
• SAM-binding proteins can be profiled using SAH capture compounds, enabling discovery of new drug targets.
• Mutations in SAM-binding pockets can alter enzyme kinetics and are associated with inherited disorders.
• SAM-dependent restriction enzymes are tools in molecular biology and antibacterial research.
• SAM binding is a key node in one-carbon metabolism and is sensitive to nutritional status.
• Structural studies of SAM-binding proteins inform the design of selective inhibitors.
• SAM binding is conserved across evolution, from bacteria to humans, making it a robust target for comparative studies.
• High-throughput screening for SAM-binding modulators can identify new therapeutics for epigenetic diseases.
Molecular Mechanism of S-adenosyl-L-methionine binding
Substrate recognition and binding pocket architecture
In simple terms: SAM fits into a specific pocket in the protein, like a key in a lock.
SAM-binding proteins typically contain a Rossmann-like fold or a radical SAM domain that coordinates the adenosyl and methionine moieties of SAM through hydrogen bonds and hydrophobic interactions. The binding pocket is highly conserved among methyltransferases, allowing specific recognition of SAM over other nucleotides. Structural analyses of O-methyltransferase-like enzymes from Aspergillus flavus reveal a conserved SAM-binding site that accommodates the cofactor in a bent conformation. The binding affinity is often in the low micromolar range, and specificity is achieved by interactions with the carboxylate and amino groups of the methionine moiety.
Conformational changes upon SAM binding
In simple terms: When SAM binds, the protein changes shape to become active.
SAM binding can induce conformational changes that reorganize the active site and promote catalysis. In human cystathionine beta-synthase, SAM binding modulates the binding of CO and NO, affecting the enzyme's heme environment and catalytic activity. Similarly, SAM activates the cardiac ryanodine receptor by binding to a regulatory site, leading to channel opening and calcium release. These examples illustrate that SAM binding is not merely a passive event but can serve as a regulatory switch.
Catalytic consequences of SAM binding
In simple terms: Once SAM is bound, it can donate its methyl group or participate in radical chemistry.
For methyltransferases, SAM binding positions the methyl group for transfer to a nucleophilic acceptor, such as a cytosine in DNA or a lysine in histones. In radical SAM enzymes, the bound SAM is reductively cleaved to generate a 5'-deoxyadenosyl radical, which initiates diverse reactions. The binding event is therefore a prerequisite for both methyl transfer and radical-based catalysis. Inhibition of SAM binding by analogs such as N-mustard SAM can irreversibly inactivate DNMT3A, demonstrating the therapeutic potential of targeting this step.
Regulation by SAM and SAH levels
In simple terms: The amount of SAM and its byproduct SAH in the cell affects how well proteins bind SAM.
Cellular SAM and SAH concentrations influence the occupancy of SAM-binding sites. SAH, the demethylated product, can act as a competitive inhibitor of SAM binding, and the SAM/SAH ratio is a sensitive indicator of methylation potential. Capture compounds based on SAH have been used to characterize SAM and SAH binding proteins, revealing that many proteins bind both ligands with different affinities. This feedback regulation ensures that methylation reactions are tightly coupled to metabolic status.
Structural diversity of SAM-binding domains
In simple terms: Different proteins use different shapes to bind SAM, but they all recognize the same molecule.
SAM-binding domains are found in multiple protein families, including class I methyltransferases, radical SAM enzymes, and the recently described SAMTOR domain in the KICSTOR-GATOR1-SAMTOR nutrient-sensing supercomplex. The SAMTOR component binds SAM to sense methionine availability and regulate mTORC1 signaling. This structural diversity allows SAM to serve as both a cofactor and a signaling molecule. Despite different folds, the binding energy is primarily contributed by the adenosyl moiety, while the methionine portion confers specificity.
Key Genes Involved in GO:1904047 S-adenosyl-L-methionine binding
The following genes encode proteins that bind S-adenosyl-L-methionine and are representative of the functional diversity of GO:1904047.
| Gene | Major Role | Research Relevance |
|---|---|---|
| DNMT3A | DNA methyltransferase that binds SAM to methylate CpG sites | Frequently mutated in cancer; target of SAM analog inhibitors |
| CBS | Cystathionine beta-synthase binds SAM to regulate H2S production | Mutations cause homocystinuria; SAM modulates CO/NO binding |
| RYR2 | Cardiac ryanodine receptor binds SAM to activate calcium release | Implicated in arrhythmias; SAM is a direct activator |
| GNMT | Glycine N-methyltransferase uses SAM as methyl donor | Deficiency leads to liver disease and hypermethioninemia |
| MTR | Methionine synthase binds SAM as a cofactor | Involved in one-carbon metabolism and neural tube defects |
| MAT1A | Methionine adenosyltransferase synthesizes SAM | Regulates SAM levels; mutations cause hypermethioninemia |
| MTHFR | Methylenetetrahydrofolate reductase affects SAM/SAH ratio | Polymorphisms linked to cardiovascular disease |
| EHMT2 | Histone methyltransferase G9a binds SAM to methylate H3K9 | Epigenetic regulator in cancer and development |
| SUV39H1 | Histone methyltransferase binds SAM for H3K9me3 | Controls heterochromatin and genome stability |
| PRMT5 | Protein arginine methyltransferase binds SAM | Regulates splicing and is a cancer target |
| DOT1L | Histone methyltransferase binds SAM for H3K79 methylation | Leukemia target; SAM-competitive inhibitors in trials |
| CARM1 | Coactivator-associated arginine methyltransferase binds SAM | Transcriptional regulation and cancer |
| SETD2 | Histone methyltransferase binds SAM for H3K36me3 | Tumor suppressor in renal cell carcinoma |
| NSUN2 | RNA methyltransferase binds SAM for m5C modification | Implicated in intellectual disability |
| METTL3 | m6A RNA methyltransferase binds SAM | Regulates mRNA stability and cancer |
| SAMTOR | SAM sensor that binds SAM to regulate mTORC1 | Links methionine availability to cell growth |
| MTRR | Methionine synthase reductase supports SAM-dependent methylation | Affects homocysteine levels |
| BHMT | Betaine-homocysteine S-methyltransferase binds SAM | Liver-specific methyl donor pathway |
How Is S-adenosyl-L-methionine binding Regulated?
SAM binding is regulated by the cellular concentrations of SAM and SAH, which are in turn controlled by one-carbon metabolism and methionine cycle enzymes. The SAM/SAH ratio serves as a metabolic indicator that modulates the activity of SAM-binding proteins; for example, SAH acts as a competitive inhibitor of methyltransferases. In addition, SAM binding to SAMTOR within the KICSTOR-GATOR1-SAMTOR complex regulates mTORC1 signaling in response to methionine availability, linking SAM sensing to cell growth control. Post-translational modifications and allosteric interactions can also influence the accessibility of SAM-binding pockets, as seen in cystathionine beta-synthase where SAM binding modulates heme ligand binding.
S-adenosyl-L-methionine binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| DNMT3A | Acute myeloid leukemia, myelodysplastic syndromes | Knockout and point-mutation cell lines; SAM analog treatment |
| CBS | Homocystinuria, cardiovascular disease | Knock-in of patient mutations; SAM binding assays |
| RYR2 | Catecholaminergic polymorphic ventricular tachycardia | Cardiomyocytes with RYR2 mutations; SAM activation studies |
| MTHFR | Neural tube defects, hyperhomocysteinemia | Overexpression and knockout models; SAM/SAH ratio measurement |
| SAMTOR | mTORC1-related metabolic disorders | Knockout of SAMTOR; methionine sensing assays |
Cancer and epigenetic dysregulation
Altered SAM binding by DNA methyltransferases such as DNMT3A contributes to aberrant DNA methylation patterns in cancer. SAM-competitive inhibitors, including N-mustard analogs, can irreversibly inhibit DNMT3A and reduce tumor growth in preclinical models. Similarly, histone methyltransferases like DOT1L and PRMT5 rely on SAM binding for their oncogenic functions, making them attractive targets for small-molecule inhibitors.
Cardiovascular and metabolic disorders
SAM binding to the cardiac ryanodine receptor (RYR2) directly activates calcium release, and dysregulation of this interaction has been linked to arrhythmias and heart failure. In cystathionine beta-synthase, SAM binding modulates the enzyme's response to CO and NO, affecting hydrogen sulfide production and vascular tone. Mutations that impair SAM binding can lead to homocystinuria and cardiovascular complications.
Neurological and developmental disorders
SAM-dependent methylation is critical for neurotransmitter synthesis and myelin maintenance. Polymorphisms in MTHFR and other one-carbon metabolism genes that affect SAM levels have been associated with neural tube defects and psychiatric disorders. Additionally, mutations in RNA methyltransferases such as NSUN2 that bind SAM can cause intellectual disability and developmental delay.
From S-adenosyl-L-methionine binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SAM binding affect enzyme activity? | Knockout cell lines (e.g., DNMT3A KO) |
| How do disease-associated mutations alter SAM affinity? | Point-mutation knock-in models (e.g., CBS mutants) |
| Can a tagged SAM-binding protein be used for interactomics? | Tagged knock-in (e.g., HA-SAMTOR) |
| What is the effect of SAM-binding protein overexpression? | Overexpression cell lines (e.g., RYR2) |
| Which genes are essential for SAM-dependent methylation? | CRISPR library screening (e.g., epigenetic regulators) |
| How does SAM binding regulate signaling pathways? | Bioinformatics analysis of transcriptomics after KO |
How to Study the S-adenosyl-L-methionine binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Isothermal titration calorimetry | Binding affinity (Kd) for SAM | Characterize mutant SAM-binding proteins |
| SAH capture pull-down | Proteins that bind SAM/SAH | Discover new SAM-binding proteins |
| X-ray crystallography | 3D structure of SAM-protein complex | Define binding pocket residues |
| CRISPR knockout | Loss-of-function phenotype | Test gene essentiality |
| Bisulfite sequencing | DNA methylation patterns | Assess DNMT3A activity |
| LC-MS/MS | SAM and SAH concentrations | Measure cellular methylation potential |
| Cryo-EM | Structure of large complexes | Visualize SAMTOR in GATOR1 complex |
| RNA-seq | Transcriptional changes | Identify pathways affected by SAM-binding mutants |
Biochemical binding assays
Direct measurement of SAM binding can be performed using isothermal titration calorimetry, surface plasmon resonance, or fluorescence polarization with labeled SAM analogs. Capture compounds based on SAH have been developed to pull down SAM-binding proteins from cell lysates, enabling proteome-wide profiling.
Structural biology
X-ray crystallography and cryo-electron microscopy have revealed the atomic details of SAM binding in diverse proteins, including O-methyltransferases and the SAMTOR complex. These structures guide mutagenesis studies to validate the binding interface.
CRISPR-based functional genomics
CRISPR knockout, point mutation, and knock-in models allow researchers to dissect the physiological consequences of perturbing SAM binding in specific genes. For example, knocking out DNMT3A or introducing catalytic mutations can reveal effects on DNA methylation and gene expression.
Methylation and metabolomics
Global DNA methylation can be assessed by bisulfite sequencing or methylation arrays, while SAM and SAH levels are quantified by LC-MS/MS. These methods link SAM binding to cellular methylation potential.
How CRISPR Can Be Used to Study GO:1904047 S-adenosyl-L-methionine binding
Knockout
CRISPR knockout of genes encoding SAM-binding proteins, such as DNMT3A or CBS, can abolish SAM binding and reveal downstream effects on methylation and metabolism. Knockout cell lines are valuable for validating drug targets and understanding loss-of-function phenotypes.
Point Mutation
Introducing point mutations in the SAM-binding pocket (e.g., in RYR2 or CBS) allows precise dissection of binding versus catalysis. Such models can mimic human disease alleles and test the efficacy of SAM analogs.
Knock-in
Knock-in of tagged SAM-binding proteins (e.g., HA-SAMTOR) enables affinity purification and interactome studies. Knock-in of disease-associated mutations can create isogenic models for drug screening.
Overexpression
Overexpression of SAM-binding proteins like RYR2 or DNMT3A can amplify signaling pathways and facilitate biochemical assays. Overexpression models are useful for testing inhibitors that compete with SAM binding.
How EDITGENE Supports S-adenosyl-L-methionine binding Research
Researchers studying S-adenosyl-L-methionine binding-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as altered methylation or disease progression. EDITGENE provides a comprehensive suite of CRISPR services to generate precisely engineered cell models, enabling functional validation of SAM-binding proteins.
Contact EDITGENE today to design your custom CRISPR model for S-adenosyl-L-methionine binding research.
Frequently Asked Questions About S-adenosyl-L-methionine binding
What is S-adenosyl-L-methionine binding?
S-adenosyl-L-methionine binding is the molecular function of selectively interacting with SAM, the primary methyl donor in cells, as defined by GO:1904047.
What genes are involved in S-adenosyl-L-methionine binding?
Genes encoding SAM-binding proteins include DNMT3A, CBS, RYR2, GNMT, MTR, MAT1A, MTHFR, EHMT2, SUV39H1, PRMT5, DOT1L, CARM1, SETD2, NSUN2, METTL3, SAMTOR, MTRR, and BHMT.
What is the GO ID for S-adenosyl-L-methionine binding?
The GO ID is GO:1904047, under the molecular_function ontology.
What is the synonym for GO:1904047?
The synonym is radical SAM enzyme activity, reflecting the historical association with radical SAM enzymes.
How is S-adenosyl-L-methionine binding studied?
It is studied using biochemical binding assays, structural biology, CRISPR-based functional genomics, and methylation/metabolomics analyses.
Why is S-adenosyl-L-methionine binding important in cancer?
Aberrant SAM binding by DNA methyltransferases like DNMT3A contributes to abnormal DNA methylation in cancer, and SAM analogs can inhibit these enzymes.
Can CRISPR be used to study S-adenosyl-L-methionine binding?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models allow precise manipulation of SAM-binding genes to study their function.
What diseases are linked to S-adenosyl-L-methionine binding defects?
Diseases include cancer, cardiovascular disorders, homocystinuria, and neurological conditions associated with altered methylation.
What is the role of SAM binding in the cardiac ryanodine receptor?
SAM binding activates the cardiac ryanodine receptor, leading to calcium release and modulation of cardiac contractility.
How does SAM binding regulate mTORC1 signaling?
The SAMTOR protein binds SAM to sense methionine availability and regulate mTORC1 signaling within the KICSTOR-GATOR1-SAMTOR complex.
Conclusion
GO:1904047, S-adenosyl-L-methionine binding, is a fundamental molecular function that governs methylation, radical chemistry, and metabolic sensing. Its importance spans cancer, cardiovascular disease, and neurological disorders, making SAM-binding proteins attractive therapeutic targets. Advances in CRISPR-based models and structural biology continue to illuminate the mechanisms and regulation of SAM binding, offering new opportunities for drug discovery and precision medicine.
References
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- 5. Vicente JB et al.. 2016. S-Adenosyl-l-methionine Modulates CO and NO• Binding to the Human H2S-generating Enzyme Cystathionine β-Synthase.. J Biol Chem 291(2):572-81 PMID: 26582199
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