GO:0141053 histone H2A ubiquitin ligase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0141053 histone H2A ubiquitin ligase activity describes the catalysis of ubiquitin transfer to a histone H2A substrate, a key chromatin-modifying molecular function.
• The Polycomb repressive complex 1 (PRC1) subunit RNF2/RING1B is the best-characterized H2A ubiquitin ligase, depositing H2AK119ub to maintain gene repression.
• RNF168 is a DNA damage-responsive H2A/H2A.X ubiquitin ligase that amplifies the ubiquitin signal at double-strand breaks to recruit repair factors.
• H2A ubiquitination is dynamically regulated by opposing enzymes, including deubiquitinases, and by crosstalk with other histone marks such as H3K9me3 and H3K14ub.
• Dysregulation of H2A ubiquitin ligases is implicated in cancer, DNA repair deficiencies, and developmental disorders, making them attractive therapeutic targets.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to dissect the causal roles of H2A ubiquitin ligases in chromatin and disease.
Description
Histone H2A ubiquitin ligase activity (GO:0141053) is a molecular function defined as the catalysis of ubiquitin transfer to a histone H2A substrate. This post-translational modification, primarily occurring on lysine 119 of H2A (H2AK119ub), is a central epigenetic mark that influences chromatin structure, gene expression, and DNA damage responses. The discovery that the Polycomb repressive complex 1 (PRC1) subunit RNF2 (also known as RING1B) possesses this activity established a direct link between ubiquitination and Polycomb-mediated gene silencing. Beyond Polycomb, RNF168 functions as a DNA damage-inducible H2A ubiquitin ligase critical for recruiting repair proteins to double-strand breaks. Researchers study GO:0141053 to understand how dynamic ubiquitination of H2A coordinates developmental gene regulation, genome stability, and disease pathogenesis. The functional versatility of H2A ubiquitination underscores its importance as a regulatory node in chromatin biology.
histone H2A ubiquitin ligase activity At A Glance
| GO ID | GO:0141053 |
|---|---|
| GO term | histone H2A ubiquitin ligase activity |
| Ontology | molecular_function |
| Synonym | none |
| Major function | Catalysis of ubiquitin transfer to histone H2A |
| Representative enzymes | RNF2/RING1B (PRC1), RNF168, and other E3 ligases |
| Key modification site | Histone H2A lysine 119 (H2AK119ub) |
| Associated processes | Polycomb-mediated gene silencing, DNA double-strand break repair, chromatin compaction |
| Disease relevance | Cancer, DNA repair disorders, developmental abnormalities |
What Is GO:0141053?
In simple terms, GO:0141053 histone H2A ubiquitin ligase activity is the enzymatic ability to attach a small protein called ubiquitin onto histone H2A. This activity is carried out by specific enzymes (E3 ligases) that recognize H2A as a substrate and catalyze the transfer of ubiquitin, typically to lysine 119. The modification can alter how chromatin is packaged and how other proteins interact with it, thereby influencing gene transcription and DNA repair.
Why Is histone H2A ubiquitin ligase activity Important in Cell Biology?
Histone H2A ubiquitin ligase activity is a cornerstone of epigenetic regulation because it directly modifies chromatin to control gene expression programs and genome stability. The H2AK119ub mark deposited by PRC1 is essential for maintaining stem cell identity and developmental gene silencing, and its dysregulation is linked to cancers and developmental syndromes. In the DNA damage response, RNF168-mediated H2A ubiquitination at double-strand breaks creates a docking site for 53BP1 and BRCA1, thereby guiding repair pathway choice. Understanding this activity provides mechanistic insights into how cells translate external signals into stable chromatin states, and it offers a target for therapeutic intervention in diseases characterized by epigenetic misregulation.
• Controls Polycomb-mediated gene repression, which is critical for embryonic development and cell fate decisions.
• Coordinates the DNA damage response by recruiting repair factors to double-strand breaks through H2A/H2A.X ubiquitination.
• Regulates chromatin compaction and higher-order chromatin organization.
• Its dysregulation is associated with multiple cancers, including lymphomas and solid tumors.
• Serves as a potential biomarker for epigenetic therapies targeting PRC1 or DNA repair pathways.
• Crosstalks with other histone modifications, such as H3K9me3 and H3K14ub, to establish repressive chromatin domains.
• Plays a role in maintaining low-density CpG methylation through UHRF1-associated ubiquitin ligase activity.
• Involved in the regulation of pathological protein aggregation, as shown by aggregate-selective degraders targeting tau.
• Contributes to cardiovascular biology, as indicated by March2-mediated regulation of PKM2 polymerization in aortic aneurysm.
• Provides a paradigm for studying E3 ligase specificity and ubiquitin signaling in chromatin.
Molecular Mechanism of histone H2A ubiquitin ligase activity
Substrate recognition and E3 ligase complexes
In simple terms: The enzyme must first grab onto histone H2A before it can attach ubiquitin.
Histone H2A ubiquitin ligases are E3 enzymes that specifically bind histone H2A within the nucleosome. The best-studied example is the PRC1 complex, in which the RING1B (RNF2) subunit forms a catalytic module with BMI1 or other PCGF proteins to recognize the nucleosomal surface. Structural and biochemical studies have revealed that PRC1 engages the nucleosome in a defined orientation that positions the RING domain for ubiquitin transfer to H2AK119. Similarly, RNF168 recognizes H2A/H2A.X at DNA damage sites, often following initial ubiquitination events, to amplify the signal. This substrate recognition is a prerequisite for catalytic activity and ensures modification specificity.
Catalytic transfer of ubiquitin to H2A
In simple terms: Once bound, the enzyme transfers a ubiquitin molecule onto a specific lysine on H2A.
The catalytic step involves the transfer of ubiquitin from a charged E2 conjugating enzyme to the target lysine on H2A, typically lysine 119. The RING domain of the E3 ligase facilitates this transfer by positioning the E2-ubiquitin thioester and the substrate lysine in close proximity. For RNF168, this activity is stimulated by its own ubiquitination and condensation at DNA damage sites, which enhances the local concentration of the enzyme and promotes H2A ubiquitination. The resulting H2AK119ub mark serves as a platform for recruiting downstream factors, such as PRC2 for H3K27 methylation or 53BP1 for repair.
Crosstalk with other histone modifications
In simple terms: The ubiquitin mark on H2A can influence, and be influenced by, other chemical tags on histones.
H2A ubiquitination does not occur in isolation; it crosstalks with other histone modifications to establish functional chromatin states. For example, H3K14ub-driven H3K9me3 is a conserved pathway for chromatin compartmentalization, and H2A ubiquitination may intersect with these repressive marks. Additionally, the SWI/SNF-related protein SMARCA3 functions as a histone H3K23 ubiquitin ligase that regulates H3K9me3 in cancer, illustrating the broader network of histone ubiquitination. Such crosstalk ensures that H2A ubiquitination is integrated into the epigenetic landscape to fine-tune gene expression and genome stability.
Regulation by deubiquitinases and dynamic cycling
In simple terms: The ubiquitin tag can be removed by other enzymes, making the process reversible and dynamic.
The levels of H2A ubiquitination are tightly controlled by the opposing action of deubiquitinases (DUBs), which remove ubiquitin from H2A. This dynamic cycling is essential for proper gene regulation and DNA repair. For instance, the HDAC6-RNF168 axis regulates H2A/H2A.X ubiquitination to enable double-strand break repair, and perturbation of this balance leads to repair defects. Similarly, UHRF1 ubiquitin ligase activity supports the maintenance of low-density CpG methylation, highlighting the interplay between ubiquitination and DNA methylation. The reversible nature of H2A ubiquitination allows cells to rapidly respond to developmental and environmental cues.
Functional consequences for chromatin and transcription
In simple terms: The ubiquitin mark changes how chromatin is packaged and whether genes are turned on or off.
H2A ubiquitination can lead to chromatin compaction and transcriptional repression, as seen in Polycomb-mediated silencing. It also serves as a signaling platform for DNA damage response factors, promoting repair and cell survival. In addition, H2A ubiquitination is involved in the regulation of pathological processes such as protein aggregation, where aggregate-selective degraders exploit ubiquitin signaling. The functional outcomes depend on the specific context, including the type of E3 ligase, the modified lysine, and the presence of reader proteins that interpret the mark.
Key Genes Involved in GO:0141053 histone H2A ubiquitin ligase activity
The following genes encode proteins that either directly catalyze histone H2A ubiquitination or are intimately involved in its regulation and downstream signaling.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RNF2 (RING1B) | Catalytic subunit of PRC1 with H2A ubiquitin ligase activity | Central to Polycomb silencing; knockout models reveal developmental roles |
| BMI1 | PRC1 component that enhances RNF2 activity | Stem cell maintenance and cancer; target for small-molecule inhibitors |
| RNF168 | E3 ligase that ubiquitinates H2A/H2A.X at DNA damage sites | DNA repair and genome stability; mutations cause RIDDLE syndrome |
| UHRF1 | Ubiquitin ligase involved in maintaining CpG methylation | Epigenetic inheritance; links ubiquitination to DNA methylation |
| SMARCA3 | Histone H3K23 ubiquitin ligase regulating H3K9me3 | Chromatin remodeling in cancer; crosstalk with H2A ubiquitination |
| HDAC6 | Deacetylase that regulates RNF168 axis | Modulates H2A/H2A.X ubiquitination in DNA repair |
| March2 | E3 ligase regulating PKM2 polymerization | Aortic aneurysm/dissection; potential link to ubiquitin signaling |
| PRC2 subunits (EZH2, SUZ12) | Deposit H3K27me3 downstream of H2A ubiquitination | Polycomb repression; cancer targets |
| 53BP1 | Reader of H2A ubiquitination at DNA breaks | DNA repair pathway choice; biomarker for repair defects |
| BRCA1 | Recruited by H2A ubiquitination for homologous recombination | Breast/ovarian cancer; synthetic lethality with PARP inhibitors |
| RNF8 | E3 ligase that initiates ubiquitin signaling at breaks | Upstream of RNF168; DNA damage response |
| BAP1 | Deubiquitinase that removes H2A ubiquitin | Tumor suppressor; mutations in mesothelioma and melanoma |
| PCGF proteins | PRC1 variants that modulate RNF2 activity | Diversity of Polycomb complexes; context-dependent functions |
| CBX proteins | Reader proteins that bind H3K27me3 and recruit PRC1 | Polycomb targeting; developmental regulation |
| RING1 | PRC1 subunit with E3 ligase activity | Embryonic development; redundancy with RNF2 |
| TRIM37 | E3 ligase with H2A ubiquitination activity | Mulibrey nanism; centrosome regulation |
| DZIP3 | H2A ubiquitin ligase involved in DNA damage response | Potential tumor suppressor; repair mechanisms |
| MYSM1 | Deubiquitinase for H2A | Hematopoiesis; immune regulation |
How Is histone H2A ubiquitin ligase activity Regulated?
Histone H2A ubiquitin ligase activity is regulated at multiple levels. The abundance and localization of E3 ligases such as RNF2 and RNF168 are controlled by transcription, post-translational modifications, and protein-protein interactions. For example, RNF168 is recruited to DNA damage sites via its ubiquitin-binding domains and undergoes ubiquitin-induced condensation, which enhances its catalytic activity. Conversely, deubiquitinases like BAP1 and MYSM1 remove H2A ubiquitin, providing a dynamic balance. Crosstalk with other histone marks, such as H3K14ub and H3K9me3, further modulates the activity and targeting of H2A ubiquitin ligases. Additionally, metabolic and signaling pathways, including the HDAC6-RNF168 axis, can influence H2A ubiquitination in response to cellular stress.
histone H2A ubiquitin ligase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RNF2 | Lymphoma, breast cancer | Knockout and overexpression in cancer cell lines; xenograft models |
| BAP1 | Mesothelioma, melanoma | Knockout in mesothelial cells; point mutations found in patients |
| RNF168 | RIDDLE syndrome, radiosensitivity | Knockout in fibroblasts; complementation with patient mutations |
| UHRF1 | Epigenetic disorders, cancer | Knockout in embryonic stem cells; methylation profiling |
| SMARCA3 | Cancer, chromatin remodeling | Knockout in cancer cell lines; H3K9me3 ChIP-seq |
Cancer
Dysregulation of H2A ubiquitin ligases is frequently observed in cancer. Overexpression of RNF2 and BMI1 is associated with lymphomas, breast cancer, and other malignancies, where they promote oncogenic gene silencing. Mutations in BAP1, a deubiquitinase that removes H2A ubiquitin, lead to mesothelioma and melanoma, highlighting the importance of balanced H2A ubiquitination. SMARCA3, a histone H3K23 ubiquitin ligase, regulates H3K9me3 in cancer, suggesting broader roles for histone ubiquitination in tumorigenesis. Targeting these enzymes is an active area of therapeutic development.
DNA repair disorders
Defects in H2A ubiquitination pathways cause genomic instability syndromes. Mutations in RNF168 result in RIDDLE syndrome, characterized by immunodeficiency, radiosensitivity, and learning difficulties. The HDAC6-RNF168 axis is critical for H2A/H2A.X ubiquitination and double-strand break repair, and its disruption leads to impaired DNA repair. These findings underscore the non-redundant role of H2A ubiquitin ligases in maintaining genome integrity.
Developmental and epigenetic disorders
Polycomb-mediated H2A ubiquitination is essential for developmental gene regulation. Perturbations in PRC1 components, including RNF2, cause developmental defects and are linked to congenital anomalies. UHRF1 ubiquitin ligase activity supports the maintenance of low-density CpG methylation, and its dysfunction may contribute to epigenetic disorders. The crosstalk between H2A ubiquitination and other repressive marks, such as H3K9me3, further emphasizes its role in establishing stable chromatin states during development.
Cardiovascular and neurodegenerative implications
Emerging evidence links ubiquitin signaling to cardiovascular and neurodegenerative diseases. March2 alleviates aortic aneurysm/dissection by regulating PKM2 polymerization, suggesting a role for E3 ligases in vascular biology. Aggregate-selective removal of pathological tau by clustering-activated degraders highlights the potential of harnessing ubiquitin ligases for neurodegenerative disease therapy. These studies indicate that H2A ubiquitin ligase activity and related ubiquitin pathways may have broader disease relevance beyond cancer.
From histone H2A ubiquitin ligase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of RNF2 abolish H2AK119ub and derepress Polycomb targets? | CRISPR knockout of RNF2 in HEK293T or mouse ES cells |
| How does a patient-derived point mutation in RNF168 affect DNA repair? | Knock-in of the mutation in U2OS cells; sensitivity assays |
| Can a tagged RNF2 be used to map genomic binding sites? | Knock-in of an epitope tag (e.g., HA) at the endogenous locus |
| What is the effect of RNF2 overexpression on tumor growth? | Overexpression in cancer cell lines; xenograft models |
| Does BAP1 deubiquitinase activity counteract H2A ubiquitination? | Knockout of BAP1; rescue with catalytically dead mutant |
| How does UHRF1 ubiquitin ligase activity maintain CpG methylation? | Knockout and point mutation of UHRF1 in mouse ES cells |
How to Study the histone H2A ubiquitin ligase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| ChIP-seq | Genome-wide localization of H2AK119ub and ligases | Mapping Polycomb targets and DNA damage sites |
| Mass spectrometry | Ubiquitination sites and histone modification crosstalk | Identifying H2A ubiquitination dynamics |
| Comet assay | DNA double-strand breaks | Assessing repair defects in RNF168 mutants |
| Immunofluorescence | Foci formation of repair proteins | Visualizing 53BP1 recruitment at damage sites |
| CRISPR knockout screens | Gene essentiality and synthetic lethality | Discovering modifiers of H2A ubiquitination |
| Western blot | H2AK119ub levels | Validating ligase activity in knockout cells |
| In vitro ubiquitination assay | Direct catalytic activity | Testing E3 ligase function with recombinant proteins |
| RNA-seq | Transcriptional changes | Measuring derepression upon ligase loss |
Chromatin immunoprecipitation and sequencing (ChIP-seq)
ChIP-seq using antibodies against H2AK119ub or tagged ligases allows genome-wide mapping of H2A ubiquitination sites and ligase binding. This method is essential to determine how H2A ubiquitin ligases contribute to gene regulation and chromatin architecture. It can be combined with knockout or point-mutation models to assess causality.
Mass spectrometry-based proteomics
Mass spectrometry can identify ubiquitination sites on H2A and quantify changes in response to genetic perturbations. This approach has been used to characterize crosstalk between H2A ubiquitination and other histone modifications. It also enables the discovery of novel E3 ligases and substrates.
DNA damage repair assays
Comet assays, gamma-H2AX foci formation, and survival assays after ionizing radiation are used to measure the functional impact of H2A ubiquitin ligases in DNA repair. These assays have been instrumental in defining the roles of RNF168 and the HDAC6-RNF168 axis.
CRISPR-based screens and functional genomics
Genome-wide CRISPR knockout screens can identify genes that modulate H2A ubiquitination or that are synthetic lethal with ligase loss. Such screens have been used to uncover vulnerabilities in cancer cells lacking BAP1 or RNF2. These approaches are powerful for target discovery and drug development.
How CRISPR Can Be Used to Study GO:0141053 histone H2A ubiquitin ligase activity
Knockout
CRISPR knockout of H2A ubiquitin ligase genes such as RNF2, RNF168, or BAP1 is a powerful way to abolish their activity and study downstream effects. For example, RNF2 knockout leads to loss of H2AK119ub and derepression of Polycomb target genes, providing insights into gene silencing. RNF168 knockout cells are hypersensitive to ionizing radiation due to defective DNA repair. These models are essential for validating the causal role of the enzyme in specific processes.
Point Mutation
Point mutations can be introduced into the catalytic domain of H2A ubiquitin ligases to separate enzymatic activity from scaffolding functions. For instance, a catalytically dead RNF168 mutant can be knocked into cells to test whether its ubiquitin ligase activity is required for DNA repair. Similarly, patient-derived mutations in BAP1 can be modeled to understand their impact on deubiquitination and tumor suppression.
Knock-in
Knock-in of epitope tags (e.g., HA, FLAG) or fluorescent proteins at the endogenous locus allows for accurate tracking of H2A ubiquitin ligases. Tagged RNF2 or RNF168 can be used for ChIP-seq, immunoprecipitation, and live-cell imaging to determine their genomic binding and dynamics. This approach preserves endogenous regulation and avoids artifacts from overexpression.
Overexpression
Overexpression of wild-type or mutant H2A ubiquitin ligases can reveal gain-of-function phenotypes. For example, overexpression of RNF2 in cancer cells promotes proliferation and tumor growth, while overexpression of a catalytically inactive mutant serves as a control. Overexpression models are useful for studying the consequences of elevated H2A ubiquitination in disease contexts.
How EDITGENE Supports histone H2A ubiquitin ligase activity Research
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Frequently Asked Questions About histone H2A ubiquitin ligase activity
What is histone H2A ubiquitin ligase activity?
It is a molecular function (GO:0141053) that catalyzes the transfer of ubiquitin to histone H2A, typically on lysine 119, thereby regulating chromatin structure and gene expression.
What genes are involved in histone H2A ubiquitin ligase activity?
Key genes include RNF2 (RING1B), RNF168, BMI1, UHRF1, and BAP1, among others.
What is the role of RNF2 in H2A ubiquitination?
RNF2 is the catalytic subunit of Polycomb repressive complex 1 (PRC1) and deposits H2AK119ub to maintain gene silencing.
How is H2A ubiquitination linked to DNA damage repair?
RNF168 ubiquitinates H2A/H2A.X at double-strand breaks, recruiting repair factors like 53BP1 and BRCA1.
What diseases are associated with H2A ubiquitin ligases?
They are implicated in cancers (e.g., lymphoma, breast cancer), RIDDLE syndrome, and developmental disorders.
Can CRISPR be used to study H2A ubiquitin ligase activity?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect the function of these enzymes.
What is H2AK119ub?
It is the ubiquitination of histone H2A at lysine 119, a mark associated with Polycomb-mediated gene repression.
How is H2A ubiquitination reversed?
Deubiquitinases such as BAP1 and MYSM1 remove ubiquitin from H2A, making the modification dynamic.
What methods are used to study H2A ubiquitin ligases?
ChIP-seq, mass spectrometry, DNA damage assays, and CRISPR screens are commonly used.
Why is H2A ubiquitination important for development?
It helps establish repressive chromatin states that control developmental gene expression programs.
Conclusion
Histone H2A ubiquitin ligase activity (GO:0141053) is a fundamental epigenetic mechanism that regulates gene expression, chromatin structure, and genome stability. The enzymes responsible, such as RNF2 and RNF168, are critical for Polycomb silencing and DNA repair, and their dysregulation contributes to cancer and other diseases. Continued research using advanced CRISPR models and multi-omics approaches will further illuminate the therapeutic potential of targeting H2A ubiquitination.
References
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- 2. Benn J et al.. 2024. Aggregate-selective removal of pathological tau by clustering-activated degraders.. Science 385(6712):1009-1016 PMID: 39208111
- 3. Li YE et al.. 2025. March2 Alleviates Aortic Aneurysm/Dissection by Regulating PKM2 Polymerization.. Circ Res 136(8):e73-e93 PMID: 40079144
- 4. Blackledge NP et al.. 2021. The molecular principles of gene regulation by Polycomb repressive complexes.. Nat Rev Mol Cell Biol 22(12):815-833 PMID: 34400841
- 5. Feng LL et al.. 2024. Ubiquitin-induced RNF168 condensation promotes DNA double-strand break repair.. Proc Natl Acad Sci U S A 121(28):e2322972121 PMID: 38968116
- 6. Akano I et al.. 2025. The SWI/SNF-related protein SMARCA3 is a histone H3K23 ubiquitin ligase that regulates H3K9me3 in cancer.. Mol Cell 85(15):2885-2899.e8 PMID: 40680746
- 7. Huang Y et al.. 2025. A conserved H3K14ub-driven H3K9me3 for chromatin compartmentalization.. Nature 647(8090):786-797 PMID: 41094145
- 8. Qiu L et al.. 2023. The HDAC6-RNF168 axis regulates H2A/H2A.X ubiquitination to enable double-strand break repair.. Nucleic Acids Res 51(17):9166-9182 PMID: 37503842
