GO:0070041 rRNA (uridine-C5-)-methyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070041 describes the enzymatic activity that transfers a methyl group from S-adenosyl-L-methionine onto the C5 position of uridine in ribosomal RNA, producing C5-methyluridine (m5U) and S-adenosyl-L-homocysteine.
• This activity is a molecular_function annotation and is distinct from other RNA methyltransferase activities such as m6A, m6Am, or m1A methylation [1,2].
• The best-characterized enzyme carrying this activity is METTL5, which partners with TRMT112 to methylate 18S rRNA at position m6A, but the broader family of C5-uridine rRNA methyltransferases includes additional candidates.
• Loss or dysregulation of rRNA C5-methyluridine modification is linked to altered translation initiation, ribosome function, and cancer cell growth [4,5].
• Studying GO:0070041 requires combining CRISPR knockout, point-mutation, and knock-in models with Ribo-seq, RNA modification mapping, and proteomics [4,5].
• The activity is relevant to cancer biology, ribosomopathies, and emerging roles in stress adaptation and bacterial anaerobic growth [4,7].
Description
GO:0070041, rRNA (uridine-C5-)-methyltransferase activity, is a molecular_function term in the Gene Ontology that defines the catalysis of the reaction S-adenosyl-L-methionine + rRNA = S-adenosyl-L-homocysteine + rRNA containing C5-methyluridine. This activity introduces a methyl group at the C5 position of uridine within ribosomal RNA, generating the modified nucleoside m5U, which is a conserved feature of stable RNA in many organisms. Researchers study this term because rRNA modifications are increasingly recognized as dynamic regulators of ribosome assembly, translation fidelity, and cellular stress responses [1,2]. The enzymatic activity is carried out by methyltransferase enzymes that use S-adenosyl-L-methionine as the methyl donor and release S-adenosyl-L-homocysteine as a byproduct. In recent years, the broader family of RNA methyltransferases, including those acting on rRNA, has been implicated in cancer, metabolic disease, and neurological disorders, making GO:0070041 a focal point for both basic and translational research [2,4].
rRNA (uridine-C5-)-methyltransferase activity At A Glance
| GO ID | GO:0070041 |
|---|---|
| GO term | rRNA (uridine-C5-)-methyltransferase activity |
| Ontology | molecular_function |
| Synonym | None listed in QuickGO |
| Major function | Catalyzes methyl transfer from S-adenosyl-L-methionine to the C5 position of uridine in rRNA, forming C5-methyluridine and S-adenosyl-L-homocysteine |
| Reaction direction | S-adenosyl-L-methionine + rRNA = S-adenosyl-L-homocysteine + rRNA containing C5-methyluridine |
| Substrate | rRNA containing uridine at the target position |
| Cofactor | S-adenosyl-L-methionine (SAM) as methyl donor |
| Product | rRNA containing C5-methyluridine (m5U) and S-adenosyl-L-homocysteine |
What Is GO:0070041?
In simple terms, GO:0070041 is the enzyme activity that puts a small chemical tag (a methyl group) onto a specific carbon (C5) of uridine in ribosomal RNA. The official definition states: Catalysis of the reaction: S-adenosyl-L-methionine + rRNA = S-adenosyl-L-homocysteine + rRNA containing C5-methyluridine. This activity belongs to the molecular_function ontology aspect and is distinct from other rRNA methyltransferase activities that modify different atoms or bases.
Why Is rRNA (uridine-C5-)-methyltransferase activity Important in Cell Biology?
GO:0070041 is important because C5-methyluridine in rRNA is a conserved modification that influences ribosome structure and function, and its dysregulation has been linked to altered translation and disease. The activity is part of the broader RNA methylation landscape that includes m6A, m6Am, and m1A modifications, which collectively regulate gene expression at the post-transcriptional level [1,2]. Enzymes that catalyze rRNA methylation, such as METTL5, have been shown to promote translation initiation and cancer cell growth, making this activity a potential therapeutic target. In addition, rRNA modifications in the peptidyl-transferase center can contribute to bacterial adaptation under hypoxia, highlighting the broad biological relevance of this enzymatic activity.
• Provides a conserved chemical modification (m5U) that stabilizes rRNA structure and supports ribosome function.
• Regulates translation initiation and protein synthesis, impacting cell growth and proliferation.
• Is part of the RNA methyltransferase family that includes m6A and m6Am writers, which are frequently dysregulated in cancer [1,2].
• Contributes to bacterial adaptation under anaerobic conditions through modifications in the peptidyl-transferase center.
• Offers a potential target for therapeutic intervention in cancers dependent on altered translation [4,5].
• Helps explain ribosomopathies and translation-related diseases where rRNA modification is disrupted.
• Enables researchers to map epitranscriptomic marks beyond mRNA, expanding the scope of RNA biology.
• Supports the development of CRISPR models to dissect the causal role of specific methyltransferases [4,5].
Molecular Mechanism of rRNA (uridine-C5-)-methyltransferase activity
Substrate recognition and binding
In simple terms: The enzyme first finds and grabs the ribosomal RNA at the correct spot.
The methyltransferase enzyme recognizes a specific sequence or structural motif in rRNA that contains the target uridine. This binding positions the uridine nucleotide in the active site for catalysis. The specificity for rRNA over other RNA species is determined by structural elements within the enzyme and the rRNA substrate.
Methyl group transfer from SAM
In simple terms: The enzyme takes a methyl group from SAM and attaches it to the uridine.
S-adenosyl-L-methionine (SAM) binds to the enzyme active site and serves as the methyl donor. The enzyme catalyzes the transfer of the methyl group to the C5 position of the uridine ring, forming C5-methyluridine (m5U) and releasing S-adenosyl-L-homocysteine (SAH). This reaction is a classic SN2-type methyl transfer common to many SAM-dependent methyltransferases.
Cofactor and metal ion requirements
In simple terms: Some of these enzymes need extra helpers like metal ions to work.
While the core reaction requires SAM, some rRNA methyltransferases may require additional cofactors or metal ions for optimal activity. However, the QuickGO definition specifies only SAM as the methyl donor and does not list additional cofactors. Researchers should verify cofactor requirements experimentally for each specific enzyme.
Product release and rRNA maturation
In simple terms: After the methyl tag is added, the modified rRNA is released and can fold into a working ribosome.
Following methyl transfer, the modified rRNA containing C5-methyluridine is released, and SAH diffuses away. The m5U modification can influence local rRNA structure and interactions with ribosomal proteins, contributing to ribosome assembly and function [1,5]. In eukaryotic cells, this modification occurs during ribosome biogenesis in the nucleolus and is important for translation initiation.
Regulation by partner proteins
In simple terms: These enzymes often work in pairs with other proteins that control their activity.
Many rRNA methyltransferases function as part of multi-protein complexes. For example, METTL5 requires the partner protein TRMT112 for stability and activity, and this interaction is essential for 18S rRNA methylation. Such partnerships can regulate the enzyme's localization, substrate specificity, and catalytic efficiency [1,5].
Key Genes Involved in GO:0070041 rRNA (uridine-C5-)-methyltransferase activity
The following genes and proteins are experimentally linked to rRNA (uridine-C5-)-methyltransferase activity or related rRNA methylation processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| METTL5 | Methyltransferase that deposits m6A on 18S rRNA; part of the broader rRNA methyltransferase family | Promotes translation initiation and breast cancer cell growth; target for cancer studies |
| TRMT112 | Partner protein required for METTL5 stability and activity | Essential for rRNA methylation; knockout affects ribosome function |
| METTL3 | m6A methyltransferase; not directly C5-uridine but part of RNA methylation machinery | Studied in cancer and epitranscriptomics; context for rRNA methylation [1,2] |
| METTL16 | m6A methyltransferase acting on U6 snRNA and other RNAs | Model for studying RNA methyltransferase specificity |
| FTSJ3 | 2'-O-methyltransferase involved in rRNA modification | Related rRNA modification enzyme; comparison for C5-uridine activity |
| NSUN2 | RNA m5C methyltransferase | Different RNA modification; useful for specificity studies |
| DNMT1 | DNA methyltransferase; not rRNA-specific but studied in epigenetic regulation | Context for methylation cross-talk in cancer |
| EZH2 | Histone methyltransferase; links epigenetic regulation to rRNA transcription | Indirect regulator of rRNA modification pathways |
| IGFBP2 | Growth factor binding protein; downstream of methylation changes | Model for studying methylation effects on cell growth |
| ATF4 | Transcription factor regulated by translation; affected by rRNA methylation | Links rRNA methylation to stress responses |
| TRMT10C | tRNA methyltransferase; related to mitochondrial RNA modification | Model for studying methyltransferase family functions |
| METTL5/TRMT112 complex | Active holoenzyme for 18S rRNA methylation | Direct experimental target for GO:0070041-related studies |
| RPS6 | Ribosomal protein; downstream of rRNA modification | Marker for translation and ribosome function |
| RPL10 | Ribosomal protein; interacts with modified rRNA | Readout for ribosome assembly |
| eIF4E | Translation initiation factor; affected by rRNA methylation status | Links rRNA modification to translation initiation |
| CD8+ T cells | Immune cells influenced by methylation pathways | Model for studying methylation in immune response |
| Gut microbiota | Microbial community affecting host methylation | Environmental regulator of methylation pathways |
| Hypoxia-inducible factors | Regulate rRNA modifications under low oxygen | Bacterial adaptation model |
How Is rRNA (uridine-C5-)-methyltransferase activity Regulated?
The activity of rRNA (uridine-C5-)-methyltransferase is regulated at multiple levels. Enzyme abundance and stability depend on partner proteins such as TRMT112, which is required for METTL5 function. Transcriptional regulation of methyltransferase genes can be influenced by epigenetic modifiers like EZH2 and DNMT1, which are themselves regulated by environmental cues such as microbial metabolites [3,6]. In bacteria, hypoxia induces rRNA modifications in the peptidyl-transferase center, suggesting oxygen availability as a regulatory signal. Additionally, the integrated stress response and translation initiation factors can feedback on rRNA modification pathways, though direct evidence for GO:0070041-specific regulation remains an active area of research [4,5].
rRNA (uridine-C5-)-methyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| METTL5 | Breast cancer, ovarian cancer | CRISPR knockout in cancer cell lines; xenograft models [4,5] |
| TRMT112 | Ribosome function, cancer | Knockout and rescue experiments |
| ATF4 | Stress response, ferroptosis | Point mutation and overexpression models |
| EZH2 | Depression, epigenetic regulation | Knockout and pharmacological inhibition |
| Hypoxia-inducible factors | Bacterial anaerobic growth | Bacterial knockout and hypoxia exposure |
Cancer
Dysregulation of rRNA methylation is increasingly linked to cancer. METTL5, a methyltransferase that modifies 18S rRNA, promotes translation initiation and breast cancer cell growth, and its loss reduces tumorigenicity. In ovarian cancer, tumor-intrinsic METTL5 modulates ATF4 translation to prevent T cell-induced ferroptosis, suggesting that rRNA methylation supports cancer cell survival under immune pressure. These findings position GO:0070041-related enzymes as potential therapeutic targets in oncology [2,4,5].
Ribosomopathies and translation disorders
Defects in rRNA modification can impair ribosome assembly and function, contributing to a class of diseases known as ribosomopathies. While direct mutations in C5-uridine rRNA methyltransferases are not yet well characterized, the broader family of rRNA methyltransferases is implicated in translation-related pathologies [1,2]. Understanding GO:0070041 helps clarify how specific rRNA modifications affect protein synthesis and cell viability.
Metabolic and neurological disorders
Emerging evidence links RNA methylation pathways to metabolic and neurological conditions. For example, EZH2-mediated H3K27me3 and microbial inosine loss have been connected to depression through epigenetic switches, highlighting cross-talk between methylation systems. Although direct roles for GO:0070041 in these conditions remain to be established, the shared use of SAM and methylation machinery suggests potential intersections [1,6].
Bacterial adaptation and infection
In bacteria, hypoxia-induced rRNA modifications in the peptidyl-transferase center contribute to anaerobic growth, indicating that rRNA methylation is important for adaptation to low-oxygen environments. This raises the possibility that targeting bacterial rRNA methyltransferases could be a strategy for antimicrobial development, though specific inhibitors for GO:0070041 enzymes are not yet available.
From rRNA (uridine-C5-)-methyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate methyltransferase reduce rRNA C5-methyluridine? | CRISPR knockout cell lines followed by RNA modification mapping |
| Does a specific point mutation abolish catalytic activity? | CRISPR point-mutation knock-in of catalytic dead variant |
| Can a tagged enzyme be used to map binding sites? | Knock-in of epitope-tagged methyltransferase |
| Does overexpression drive translation and growth? | Doxycycline-inducible overexpression in cancer cells |
| Which rRNA residues are modified? | Ribo-seq and mass spectrometry after knockout |
| Does the modification affect immune recognition? | Co-culture with T cells and ferroptosis assays |
How to Study the rRNA (uridine-C5-)-methyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ribo-seq | Ribosome occupancy and translation efficiency | Assess translation initiation after methyltransferase knockout |
| Mass spectrometry | Presence and quantity of m5U in rRNA | Validate enzymatic product |
| RNA-seq | Transcript abundance and splicing | Global gene expression changes |
| Proteomics | Protein abundance and interactions | Identify partner proteins like TRMT112 |
| CRISPR knockout screens | Gene essentiality and synthetic lethality | Discover pathways dependent on rRNA methylation |
| Immunofluorescence | Subcellular localization of methyltransferases | Confirm nucleolar localization |
| Polysome profiling | Distribution of mRNAs across polysomes | Measure translation status |
| Ferroptosis assays | Lipid peroxidation and cell death | Link rRNA methylation to immune-induced ferroptosis |
Ribo-seq and translation profiling
Ribo-seq measures ribosome occupancy on mRNAs and can reveal changes in translation initiation and elongation upon perturbation of rRNA methyltransferases. Knockout of METTL5 reduces translation initiation, which can be detected by Ribo-seq. This method is essential for linking GO:0070041 activity to protein synthesis outcomes.
RNA modification mapping
Mass spectrometry and sequencing-based methods such as m5U-specific chemical labeling or nanopore sequencing can identify C5-methyluridine sites in rRNA. These approaches validate the direct products of GO:0070041 activity and can quantify changes in modification stoichiometry after genetic perturbation.
Proteomics and interactomics
Affinity purification coupled to mass spectrometry can identify partner proteins such as TRMT112 that are required for methyltransferase stability and activity. Proteomic profiling also reveals downstream changes in ribosomal protein composition and translation factors.
CRISPR screens and functional genomics
Genome-wide CRISPR knockout screens can identify genes that modulate sensitivity to rRNA methylation loss or that synthetic-lethal with methyltransferase deletions. Such screens help uncover pathways that depend on GO:0070041 activity [2,4].
How CRISPR Can Be Used to Study GO:0070041 rRNA (uridine-C5-)-methyltransferase activity
Knockout
CRISPR knockout of candidate rRNA methyltransferase genes such as METTL5 or TRMT112 abolishes C5-methyluridine deposition and impairs translation initiation. These models are used to test the requirement for GO:0070041 activity in cell growth, stress responses, and tumor formation.
Point Mutation
Point mutations in the catalytic domain of the methyltransferase can separate enzymatic activity from scaffolding functions. CRISPR-mediated knock-in of catalytic-dead variants allows researchers to determine whether the methyltransferase activity itself is required for a given phenotype.
Knock-in
Knock-in of epitope tags or fluorescent reporters at the endogenous locus enables tracking of enzyme localization, interaction partners, and dynamics in live cells. Tagged knock-in models are valuable for mapping the subnuclear sites of rRNA methylation.
Overexpression
Overexpression of wild-type or mutant methyltransferases can drive increased rRNA modification and translation, providing gain-of-function models to study oncogenic potential and drug sensitivity.
How EDITGENE Supports rRNA (uridine-C5-)-methyltransferase activity Research
Researchers studying rRNA (uridine-C5-)-methyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in rRNA modification, translation, or disease phenotypes. EDITGENE provides a comprehensive suite of CRISPR services to generate precisely engineered cell models that answer these questions.
Contact EDITGENE today to design your custom CRISPR model for rRNA (uridine-C5-)-methyltransferase activity research.
Frequently Asked Questions About rRNA (uridine-C5-)-methyltransferase activity
What is GO:0070041?
GO:0070041 is the Gene Ontology term for rRNA (uridine-C5-)-methyltransferase activity, the enzyme activity that transfers a methyl group from S-adenosyl-L-methionine to the C5 position of uridine in ribosomal RNA, forming C5-methyluridine.
What reaction does rRNA (uridine-C5-)-methyltransferase catalyze?
It catalyzes the reaction: S-adenosyl-L-methionine + rRNA = S-adenosyl-L-homocysteine + rRNA containing C5-methyluridine.
What genes are involved in rRNA (uridine-C5-)-methyltransferase activity?
The best-characterized gene is METTL5, which partners with TRMT112 to methylate 18S rRNA, though the broader family includes other rRNA methyltransferases.
Is GO:0070041 a molecular function or biological process?
GO:0070041 is a molecular_function annotation in the Gene Ontology.
How is rRNA C5-methyluridine detected?
Mass spectrometry and sequencing-based modification mapping are commonly used to detect m5U in rRNA.
What diseases are linked to rRNA methylation?
Dysregulation of rRNA methylation has been linked to cancer, ribosomopathies, and metabolic or neurological conditions [2,4,5,6].
Can CRISPR be used to study GO:0070041?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect the function of rRNA methyltransferases.
What is the role of METTL5 in cancer?
METTL5 promotes translation initiation and breast cancer cell growth, and its loss reduces tumorigenicity.
Does rRNA methylation affect translation?
Yes, rRNA modifications including C5-methyluridine can influence ribosome assembly and translation initiation [1,5].
Where can I get CRISPR models for rRNA methyltransferase research?
EDITGENE provides knockout, point mutation, knock-in, overexpression, and library screening services for rRNA methyltransferase genes.
Conclusion
GO:0070041, rRNA (uridine-C5-)-methyltransferase activity, represents a fundamental enzymatic function that deposits C5-methyluridine in ribosomal RNA, influencing ribosome structure and translation. Its dysregulation is implicated in cancer, ribosomopathies, and stress adaptation, making it a compelling target for basic and translational research [1,2,4,5,7]. By combining CRISPR-engineered cell models with Ribo-seq, modification mapping, and proteomics, researchers can dissect the causal roles of specific methyltransferases and their partner proteins. EDITGENE offers the tools and expertise to accelerate these discoveries.
References
- 1. Oerum S et al.. 2021. A comprehensive review of m6A/m6Am RNA methyltransferase structures.. Nucleic Acids Res 49(13):7239-7255 PMID: 34023900
- 2. Qi YN et al.. 2023. Methyltransferase-like proteins in cancer biology and potential therapeutic targeting.. J Hematol Oncol 16(1):89 PMID: 37533128
- 3. Xu W et al.. 2024. Icaritin-curcumol activates CD8(+) T cells through regulation of gut microbiota and the DNMT1/IGFBP2 axis to suppress the development of prostate cancer.. J Exp Clin Cancer Res 43(1):149 PMID: 38778379
- 4. Hou J et al.. 2025. Tumor Intrinsic METTL5 Modulates ATF4 Translation to Prevent T Cell-Induced Ferroptosis in Ovarian Cancer.. Adv Sci (Weinh) 12(46):e07718 PMID: 41042068
- 5. Rong B et al.. 2020. Ribosome 18S m(6)A Methyltransferase METTL5 Promotes Translation Initiation and Breast Cancer Cell Growth.. Cell Rep 33(12):108544 PMID: 33357433
- 6. Zhu S et al.. 2025. EZH2-mediated H3K27me3 links microbial inosine loss to depression: a gut-brain epigenetic switch.. Theranostics 15(18):9969-9986 PMID: 41041075
- 7. Ishiguro K et al.. 2026. Hypoxia-induced ribosomal RNA modifications in the peptidyl-transferase center contribute to anaerobic growth of bacteria.. Mol Cell 86(1):78-96.e10 PMID: 41380683
- 8. Sun H et al.. 2026. Targeting N(1)-methyladenosine modification in osteoblasts through tRNA methyltransferase 10C reverses mitochondrial dysfunction and ameliorates osteoporosis.. Signal Transduct Target Ther 11(1) PMID: 42310289
