GO:0034708 methyltransferase complex: Components, Assembly and Research Methods, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034708 methyltransferase complex is a cellular component defined as a protein complex that possesses methyltransferase activity.
• The METTL3-METTL14 complex is the core m6A RNA methyltransferase complex in mammals, and its subunits are functionally interdependent.
• The MLL3/4 H3K4 methyltransferase complex establishes active enhancer landscapes and is linked to gene regulation.
• Structural and biochemical studies show cooperative function between Mettl3 and Mettl14, with METTL14 stabilizing METTL3 and contributing to substrate recognition.
• Cotranslational assembly directs the biogenesis of the m6A methyltransferase complex, revealing a layer of regulation in complex formation.
• Methyltransferase complexes are conserved across archaea, plants, and mammals, with examples including the Na+-translocating methyltransferase complex and Arabidopsis m6A methyltransferase complex.
Description
Methyltransferase complexes are multimeric protein assemblies that catalyze the transfer of methyl groups to diverse substrates, including DNA, RNA, and proteins. As a Gene Ontology cellular component term, GO:0034708 encompasses any protein complex that possesses methyltransferase activity, reflecting the growing recognition that many methyltransferases function not in isolation but as part of obligate or facultative complexes. The METTL3-METTL14 complex, for example, is the core mammalian RNA N6-adenosine methyltransferase and is essential for m6A deposition on nuclear RNAs. Similarly, the MLL3/4 H3K4 methyltransferase complex plays a critical role in establishing active enhancer landscapes and regulating gene expression programs. These complexes are conserved across evolution, from archaeal Na+-translocating methyltransferase complexes to plant m6A methyltransferase complexes, underscoring their fundamental importance in cellular physiology. Researchers study methyltransferase complexes to understand how substrate specificity, catalytic activity, and biological outputs are achieved through protein-protein interactions and dynamic assembly.
methyltransferase complex At A Glance
| GO ID | GO:0034708 |
|---|---|
| GO term | methyltransferase complex |
| Ontology | cellular_component |
| Synonym | none |
| Major function | Catalysis of methyl group transfer to substrates such as RNA, DNA, or proteins |
| Example complex | METTL3-METTL14 m6A RNA methyltransferase complex |
| Conservation | Found in archaea, plants, and mammals |
| Substrate types | RNA (m6A, m3C), histone proteins (H3K4), and others |
| Assembly regulation | Cotranslational assembly and subunit interdependence |
What Is GO:0034708?
GO:0034708 methyltransferase complex is defined as a protein complex that possesses methyltransferase activity. This means the complex as a whole can catalyze the transfer of a methyl group from a donor (typically S-adenosylmethionine) to a substrate, and the complex may consist of one or more catalytic subunits plus accessory proteins that regulate activity, specificity, or assembly.
Why Is methyltransferase complex Important in Cell Biology?
Methyltransferase complexes are central to epigenetic and epitranscriptomic regulation, controlling gene expression, RNA stability, and chromatin states. Dysregulation of these complexes is linked to cancer, developmental disorders, and other diseases, making them attractive therapeutic targets. Understanding their structure, assembly, and regulation provides mechanistic insights into fundamental biology and supports drug discovery efforts.
• They mediate m6A RNA methylation, a reversible modification affecting RNA fate.
• They establish active enhancer landscapes through H3K4 methylation.
• They are conserved across all domains of life, indicating essential roles.
• Their dysfunction is implicated in cancer and other diseases.
• They are targets for small-molecule degraders such as PROTACs.
• Their assembly is regulated cotranslationally, adding a layer of control.
• They provide models for studying protein complex cooperativity.
• They are studied in plants for roles in development and stress responses.
• They include tRNA methyltransferases like METTL6 in complex with SerRS.
• They are key to understanding epigenetic drug mechanisms.
What Happens During methyltransferase complex?
Subunit Assembly and Stoichiometry
In simple terms: The complex is built from multiple protein subunits that come together in specific ratios.
Methyltransferase complexes often require obligate heterodimers or larger assemblies for activity. For example, the METTL3-METTL14 complex forms a heterodimer where METTL14 stabilizes METTL3 and contributes to RNA binding, while METTL3 contains the catalytic domain. In Arabidopsis, m6A methyltransferase complex subunits show functional interdependence, meaning loss of one subunit affects the stability or activity of others. Cotranslational assembly further directs the biogenesis of the m6A methyltransferase complex, ensuring proper subunit folding and interaction.
Substrate Recognition and Binding
In simple terms: The complex recognizes specific target sequences or structures in RNA, DNA, or proteins.
Substrate specificity is achieved through structural features of the complex. The METTL3-METTL14 complex recognizes RNA substrates with a preference for certain sequence motifs, and structural studies reveal how the subunits cooperate to bind RNA. METTL6 in complex with SerRS seryl-tRNA synthetase recognizes tRNA substrates for m3C methylation, demonstrating how complex formation expands substrate repertoire. The MLL3/4 complex recognizes histone H3 tails for K4 methylation, influencing enhancer activity.
Catalysis and Methyl Group Transfer
In simple terms: The complex transfers a methyl group from a donor molecule to the substrate.
Catalysis occurs at the active site of the methyltransferase subunit, often requiring cofactors such as S-adenosylmethionine (SAM) as the methyl donor. In the METTL3-METTL14 complex, METTL3 catalyzes m6A formation, while METTL14 plays a structural and regulatory role. The Na+-translocating methyltransferase complex from methanogenic archaea couples methyl group transfer to ion translocation, illustrating diverse catalytic mechanisms.
Regulation and Dynamics
In simple terms: The activity and assembly of the complex can be turned up or down by cellular signals.
Methyltransferase complex activity is regulated at multiple levels, including subunit expression, post-translational modifications, and interaction with regulatory proteins. For instance, the METTL3-METTL14 complex can be targeted for degradation by PROTACs, demonstrating that its levels can be pharmacologically controlled. Cotranslational assembly provides a regulatory checkpoint for complex formation. In plants, subunit interdependence ensures that complex integrity is maintained.
Key Genes Involved in GO:0034708 methyltransferase complex
The following genes encode subunits or associated proteins of methyltransferase complexes across species.
| Gene | Major Role | Research Relevance |
|---|---|---|
| METTL3 | Catalytic subunit of m6A RNA methyltransferase complex | Target for cancer therapy and RNA epigenetics |
| METTL14 | Essential subunit stabilizing METTL3 and aiding RNA binding | Mutations linked to diseases; structural studies |
| WTAP | Regulatory subunit of m6A complex | Affects complex localization and activity |
| MLL3 (KMT2C) | H3K4 methyltransferase complex subunit | Enhancer regulation and cancer |
| MLL4 (KMT2D) | H3K4 methyltransferase complex subunit | Enhancer regulation and developmental disorders |
| METTL6 | tRNA m3C methyltransferase | Complex with SerRS for tRNA modification |
| SerRS | Seryl-tRNA synthetase, partner of METTL6 | tRNA recognition and modification |
| MTA1 | Component of NuRD complex with methyltransferase activity | Chromatin remodeling and cancer |
| MTA2 | Component of NuRD complex | Chromatin remodeling |
| MTA3 | Component of NuRD complex | Chromatin remodeling |
| RbBP5 | Subunit of MLL3/4 complex | Enhancer regulation |
| Ash2L | Subunit of MLL3/4 complex | Enhancer regulation |
| WDR5 | Subunit of MLL3/4 complex | Enhancer regulation |
| DPY30 | Subunit of MLL3/4 complex | Enhancer regulation |
| VIRMA | Regulatory subunit of m6A complex | Complex assembly and RNA methylation |
| ZC3H13 | Regulatory subunit of m6A complex | Complex assembly |
| FTO | m6A demethylase, eraser | Opposes methyltransferase complex |
How Is methyltransferase complex Regulated?
Methyltransferase complex assembly and activity are regulated at multiple levels. Cotranslational assembly directs the biogenesis of the m6A methyltransferase complex, ensuring proper subunit folding and interaction. Subunit interdependence, as seen in Arabidopsis, means that loss of one subunit can destabilize the entire complex. Pharmacological regulation is possible; PROTAC degraders can specifically target the METTL3-METTL14 complex for degradation. Additionally, post-translational modifications and interacting proteins may modulate complex activity, though specific mechanisms require further study.
methyltransferase complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| METTL3 | Cancer, RNA methylation dysregulation | Knockout and overexpression cell lines |
| METTL14 | Cancer, developmental defects | Point mutation knock-in models |
| MLL3 (KMT2C) | Cancer, enhancer dysregulation | Knockout and tagged knock-in |
| MLL4 (KMT2D) | Kabuki syndrome, cancer | Knock-in of patient mutations |
| METTL6 | tRNA modification, potential cancer link | Knockout and complex reconstitution |
Cancer
Dysregulation of methyltransferase complexes is frequently observed in cancer. The METTL3-METTL14 complex is overexpressed in various cancers and promotes tumor progression through m6A modification of oncogenes and tumor suppressors. The MLL3/4 H3K4 methyltransferase complex is mutated in multiple cancer types, affecting enhancer landscapes and gene expression. Targeting these complexes with small molecules or degraders is a promising therapeutic strategy.
Developmental Disorders
Mutations in genes encoding methyltransferase complex subunits can cause developmental disorders. For example, mutations in MLL4 (KMT2D) are associated with Kabuki syndrome, characterized by developmental abnormalities. Disruption of m6A methyltransferase complex components in model organisms leads to developmental defects, highlighting their essential roles.
Neurological and Metabolic Diseases
Emerging evidence links methyltransferase complexes to neurological and metabolic diseases. Altered m6A methylation is implicated in neurodegeneration and metabolic disorders, though the exact mechanisms are under investigation. The Na+-translocating methyltransferase complex in archaea serves as a model for understanding related processes in other systems.
From methyltransferase complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of METTL3 affect m6A levels? | METTL3 knockout cell line |
| How do point mutations in METTL14 affect complex stability? | Point mutation knock-in |
| Can we tag the complex for imaging? | Tagged knock-in of METTL3 or METTL14 |
| What is the effect of METTL3 overexpression? | Overexpression cell line |
| Can we degrade the complex pharmacologically? | PROTAC treatment in cells |
| How does MLL4 mutation affect enhancers? | Knockout and rescue with wild-type or mutant |
How to Study the methyltransferase complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| MeRIP-seq | m6A modification sites | Mapping RNA methylation changes |
| RNA-seq | Gene expression changes | Transcriptome analysis upon complex perturbation |
| Affinity purification-MS | Protein interactions | Identifying complex subunits |
| Cryo-EM | 3D structure | Structural basis of complex function |
| Ribosome profiling | Translation dynamics | Cotranslational assembly studies |
| CRISPR screen | Gene essentiality and modifiers | Discovering regulators of complex |
| Western blot | Protein levels | Validating knockout or overexpression |
| Immunofluorescence | Localization | Visualizing complex in cells |
RNA Sequencing and m6A Mapping
RNA-seq and m6A-specific techniques such as MeRIP-seq are used to map m6A modifications and assess the impact of methyltransferase complex perturbation on transcriptomes. These methods reveal target genes and pathways regulated by the complex.
Proteomics and Complex Purification
Affinity purification coupled with mass spectrometry identifies subunits and interacting partners of methyltransferase complexes. For example, purification of the METTL3-METTL14 complex revealed associated proteins like WTAP. Structural studies using cryo-EM or X-ray crystallography provide mechanistic insights.
Imaging and Live-Cell Tracking
Fluorescence microscopy with tagged subunits allows visualization of complex localization and dynamics in living cells. Cotranslational assembly can be studied using ribosome profiling and imaging.
CRISPR Screening
Genome-wide CRISPR screens can identify genes that modulate methyltransferase complex function or sensitivity to inhibitors. This approach is powerful for discovering novel regulators and therapeutic targets.
How CRISPR Can Be Used to Study GO:0034708 methyltransferase complex
Knockout
CRISPR knockout of genes encoding methyltransferase complex subunits, such as METTL3 or METTL14, is used to study loss-of-function phenotypes, including effects on m6A levels, gene expression, and cell viability. Knockout cell lines serve as valuable models for drug discovery and functional studies.
Point Mutation
Point mutation knock-in via CRISPR allows precise modeling of disease-associated mutations or catalytic dead variants. For example, mutating the catalytic residue of METTL3 can distinguish catalytic activity from structural roles. Such models are essential for understanding mechanism and validating drug targets.
Knock-in
Knock-in of tags (e.g., GFP, HA) or reporter genes enables visualization and purification of methyltransferase complexes. Tagged knock-in of METTL3 or METTL14 facilitates live-cell imaging and proteomic studies. Knock-in of patient mutations can model disease in isogenic backgrounds.
Overexpression
Overexpression of methyltransferase complex subunits, such as METTL3, is used to study gain-of-function effects, including increased m6A methylation and oncogenic transformation. Overexpression models help identify downstream pathways and potential therapeutic vulnerabilities.
How EDITGENE Supports methyltransferase complex Research
Researchers studying methyltransferase complex-related genes often need to determine whether a candidate gene is causally involved in complex assembly, catalysis, or disease. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for methyltransferase complex research.
Frequently Asked Questions About methyltransferase complex
What is GO:0034708 methyltransferase complex?
GO:0034708 is a Gene Ontology cellular component term defined as a protein complex that possesses methyltransferase activity.
What genes are involved in methyltransferase complex?
Key genes include METTL3, METTL14, WTAP, MLL3, MLL4, METTL6, and others encoding subunits of various methyltransferase complexes.
What is the function of the METTL3-METTL14 complex?
It catalyzes m6A RNA methylation, a critical epitranscriptomic modification affecting RNA stability and translation.
How is the methyltransferase complex assembled?
Assembly involves subunit interdependence and can be cotranslationally regulated, as shown for the m6A methyltransferase complex.
What diseases are linked to methyltransferase complex dysfunction?
Dysregulation is linked to cancer, developmental disorders like Kabuki syndrome, and potentially neurological diseases.
Can methyltransferase complexes be targeted by drugs?
Yes, PROTAC degraders have been developed to target the METTL3-METTL14 complex, showing therapeutic potential.
What methods are used to study methyltransferase complexes?
Common methods include MeRIP-seq, RNA-seq, proteomics, cryo-EM, and CRISPR screens.
What is the role of MLL3/4 complex?
It establishes active enhancer landscapes through H3K4 methylation, regulating gene expression.
How does METTL6 function in tRNA methylation?
METTL6 forms a complex with SerRS to recognize and methylate tRNA, demonstrating complex-dependent substrate specificity.
Are methyltransferase complexes conserved?
Yes, they are found in archaea, plants, and mammals, indicating fundamental roles.
Conclusion
GO:0034708 methyltransferase complex represents a diverse and essential class of molecular machines that catalyze methylation of RNA, DNA, and proteins. From the well-studied METTL3-METTL14 m6A complex to the MLL3/4 histone methyltransferase complex, these assemblies control gene expression and cellular physiology. Their dysfunction is linked to cancer and developmental disorders, making them prime targets for therapeutic intervention. Continued research into their structure, assembly, and regulation will uncover new biological insights and therapeutic opportunities.
References
- 1. Liu J et al.. 2014. A METTL3-METTL14 complex mediates mammalian nuclear RNA N6-adenosine methylation.. Nat Chem Biol 10(2):93-5 PMID: 24316715
- 2. Du W et al.. 2024. Discovery of a PROTAC degrader for METTL3-METTL14 complex.. Cell Chem Biol 31(1):177-183.e17 PMID: 38194973
- 3. Wang LH et al.. 2021. The MLL3/4 H3K4 methyltransferase complex in establishing an active enhancer landscape.. Biochem Soc Trans 49(3):1041-1054 PMID: 34156443
- 4. Shen L. 2023. Functional interdependence of N6-methyladenosine methyltransferase complex subunits in Arabidopsis.. Plant Cell 35(6):1901-1916 PMID: 36890720
- 5. Throll P et al.. 2024. Structural basis of tRNA recognition by the m(3)C RNA methyltransferase METTL6 in complex with SerRS seryl-tRNA synthetase.. Nat Struct Mol Biol 31(10):1614-1624 PMID: 38918637
- 6. Wang P et al.. 2016. Structural Basis for Cooperative Function of Mettl3 and Mettl14 Methyltransferases.. Mol Cell 63(2):306-317 PMID: 27373337
- 7. Gottschalk G et al.. 2001. The Na(+)-translocating methyltransferase complex from methanogenic archaea.. Biochim Biophys Acta 1505(1):28-36 PMID: 11248186
- 8. Wu X et al.. 2026. Cotranslational assembly directs the biogenesis of the m(6)A methyltransferase complex.. Proc Natl Acad Sci U S A 123(1):e2517258123 PMID: 41481436
