GO:0019985 translesion synthesis: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0019985 translesion synthesis is the replication of damaged DNA by synthesis across a lesion in the template strand, allowing DNA synthesis to continue beyond the lesion.
• Specialized DNA polymerases insert a defined nucleotide across from the lesion, and the process can be mutagenic depending on the damaged nucleotide and the inserted nucleotide.
• Translesion synthesis is a major mechanism of DNA damage tolerance and is conserved from plants to mammals [2,8].
• Protein assemblies and post-translational modifications regulate translesion synthesis in mammalian cells [3,8].
• Translesion synthesis inhibitors are being developed as a new class of cancer chemotherapeutics.
• Dysregulated translesion synthesis contributes to carcinogenesis and can be targeted to enhance genotoxic chemotherapy [1,6].
Description
Translesion synthesis (TLS) is a specialized DNA damage tolerance pathway that allows replication to proceed past DNA lesions that would otherwise stall the replicative polymerase. This process is defined by the insertion of a nucleotide across from a damaged template base, followed by extension, and is carried out by specialized DNA polymerases that can accommodate distorted template structures [1,8]. Because TLS can be error-prone, it is a double-edged sword: it protects cells from replication fork collapse and apoptosis, but it can also introduce mutations that drive carcinogenesis. In plants, TLS contributes to ultraviolet resistance and other stress responses, highlighting its evolutionary conservation. In trypanosomatids, TLS is intertwined with microhomology-mediated end-joining repair, underscoring its broader role in genome maintenance. Understanding TLS is therefore critical for cancer biology, chemotherapy development, and genome stability research [4,6].
translesion synthesis At A Glance
| GO ID | GO:0019985 |
|---|---|
| GO term | translesion synthesis |
| Ontology | biological_process |
| Synonym | bypass DNA synthesis |
| Major function | Replication of damaged DNA by synthesis across a lesion in the template strand |
| Mechanistic outcome | A specialized DNA polymerase or replication complex inserts a defined nucleotide across from the lesion |
| Consequence | Allows DNA synthesis to continue beyond the lesion; can be mutagenic depending on the damaged nucleotide and the inserted nucleotide |
| Conservation | Observed in plants, mammals, and trypanosomatids [2,5,8] |
| Therapeutic relevance | Translesion synthesis inhibitors are explored as cancer chemotherapeutics |
What Is GO:0019985?
According to the Gene Ontology, GO:0019985 translesion synthesis is defined as the replication of damaged DNA by synthesis across a lesion in the template strand; a specialized DNA polymerase or replication complex inserts a defined nucleotide across from the lesion, which allows DNA synthesis to continue beyond the lesion. This process can be mutagenic depending on the damaged nucleotide and the inserted nucleotide. The synonym bypass DNA synthesis is also used.
Why Is translesion synthesis Important in Cell Biology?
Translesion synthesis is essential for cell survival when replication forks encounter DNA lesions, but its error-prone nature can introduce mutations that contribute to cancer and other diseases. In mammalian cells, TLS is tightly regulated by protein assemblies and post-translational modifications to balance genome stability and mutagenesis [3,8]. In plants, TLS supports ultraviolet resistance and broader stress responses. In trypanosomatids, TLS cooperates with microhomology-mediated end-joining, revealing diverse roles in genome maintenance. Because TLS can promote resistance to genotoxic chemotherapy, inhibiting this pathway is a promising therapeutic strategy [4,6].
• TLS allows replication to bypass DNA lesions that would otherwise stall the replikative polymerase, preventing fork collapse.
• TLS is a major source of mutagenesis and contributes to carcinogenesis.
• TLS inhibitors are being developed as a new class of cancer chemotherapeutics.
• In epithelial ovarian cancer, tyrosine catabolism suppresses TLS and enhances genotoxic chemotherapy.
• TLS is conserved in plants, where it contributes to ultraviolet resistance and beyond.
• In trypanosomatids, TLS is linked to microhomology-mediated end-joining repair.
• Protein assemblies and post-translational modifications regulate TLS in mammalian cells [3,8].
• Post-TLS repair pathways further process the bypassed lesion to restore genome integrity.
• TLS polymerases are potential biomarkers and targets for precision oncology [4,6].
• Understanding TLS mechanisms aids in predicting responses to DNA-damaging agents [1,4].
What Happens During translesion synthesis?
Lesion recognition and polymerase switching
In simple terms: When the DNA copying machine hits a damaged spot, it stalls and calls in a specialist to take over.
During replication, a replicative DNA polymerase encounters a lesion in the template strand and stalls. This triggers a switch to a specialized translesion synthesis polymerase that can accommodate the distorted template [1,8]. In mammalian cells, this switch is regulated by protein-protein interactions and post-translational modifications that ensure the right polymerase is recruited to the right lesion [3,8].
Nucleotide insertion across from the lesion
In simple terms: The specialist enzyme puts a nucleotide opposite the damage, even if it is not a perfect match.
The specialized polymerase inserts a defined nucleotide across from the lesion. The identity of the inserted nucleotide depends on the type of damage and the polymerase involved, and this step can be error-prone or error-free. This insertion is the defining catalytic event of translesion synthesis.
Extension beyond the lesion
In simple terms: After placing the nucleotide, the enzyme extends the new strand so copying can continue.
Following insertion, the polymerase or a second specialized polymerase extends the primer beyond the lesion, allowing DNA synthesis to continue. This extension step is often carried out by a different polymerase with appropriate extension properties.
Post-translesion synthesis repair
In simple terms: After bypass, the cell may still need to fix the original damage to keep the genome stable.
After TLS, the lesion may remain in the DNA and be processed by post-translesion synthesis repair pathways to restore genome integrity. This highlights that TLS is not the final solution but part of a coordinated damage tolerance network.
Regulation and protein assemblies
In simple terms: Many proteins come together and are chemically modified to control when and where TLS happens.
TLS is regulated by the assembly of multi-protein complexes and by post-translational modifications such as ubiquitination and phosphorylation [3,8]. These regulatory layers ensure that TLS occurs at the right time and place, balancing survival and mutagenesis.
Key Genes Involved in GO:0019985 translesion synthesis
The following genes and proteins are central to translesion synthesis, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| POLH | Specialized DNA polymerase for TLS across UV lesions | Xeroderma pigmentosum variant; UV resistance [1,2] |
| POLI | TLS polymerase involved in bypass of various lesions | Mutagenesis and cancer [1,8] |
| POLK | TLS polymerase for bulky lesions | Cancer chemotherapy response |
| REV1 | Scaffold protein in TLS polymerase complexes | Protein assembly and regulation |
| REV3L | Catalytic subunit of polymerase zeta | TLS extension and mutagenesis |
| REV7 | Accessory subunit of polymerase zeta | TLS regulation and cancer |
| PCNA | Sliding clamp modified by ubiquitination to recruit TLS polymerases | Polymerase switching |
| RAD18 | E3 ubiquitin ligase that monoubiquitinates PCNA | TLS activation |
| UBE2B | Ubiquitin-conjugating enzyme in TLS | Regulation of PCNA ubiquitination |
| POLN | TLS polymerase | Lesion bypass |
| POLQ | Polymerase involved in TLS and other repair | Cancer therapy resistance |
| MAD2L2 | Alternative name for REV7 | TLS complex assembly |
| POLD3 | Accessory subunit of polymerase delta | TLS and replication |
| POLD4 | Accessory subunit of polymerase delta | TLS and replication |
| HERC2 | Regulator of PCNA ubiquitination | TLS regulation |
| USP1 | Deubiquitinase that regulates PCNA | TLS and chemotherapy response |
| FANCD2 | Fanconi anemia protein linked to TLS | Crosslink repair and TLS |
How Is translesion synthesis Regulated?
Translesion synthesis is regulated at multiple levels, including post-translational modifications of PCNA (such as monoubiquitination by RAD18) that recruit specialized polymerases, and the assembly of multi-protein complexes involving REV1, REV3L, and REV7 [3,8]. In mammalian cells, additional regulatory mechanisms include phosphorylation and ubiquitination of TLS polymerases, which control their localization and activity. In plants, TLS is regulated in response to ultraviolet stress. In trypanosomatids, TLS is coordinated with microhomology-mediated end-joining. Post-translesion synthesis repair pathways further modulate the outcome of TLS.
translesion synthesis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| POLH | Xeroderma pigmentosum variant | Knockout in human fibroblasts |
| REV1 | Cancer chemotherapy response | Knockout in cancer cell lines |
| REV3L | Cancer mutagenesis | Point mutation in mouse models |
| PCNA | Cancer and genome instability | Knock-in of ubiquitination-deficient mutant |
| USP1 | Chemotherapy resistance | Overexpression in ovarian cancer cells |
Translesion synthesis and cancer
Dysregulated TLS contributes to carcinogenesis by promoting mutagenesis and allowing cancer cells to survive DNA-damaging chemotherapy. Inhibitors of TLS are being developed as a new class of cancer chemotherapeutics. In epithelial ovarian cancer, tyrosine catabolism suppresses TLS and enhances the efficacy of genotoxic chemotherapy.
Translesion synthesis in chemotherapy resistance
TLS can confer resistance to platinum-based and other DNA-damaging agents by bypassing drug-induced lesions. Targeting TLS polymerases or their regulators is a strategy to sensitize tumors to chemotherapy [4,6].
Translesion synthesis in other diseases
Defects in TLS can lead to genome instability syndromes, and TLS is also implicated in trypanosomatid biology, where it cooperates with microhomology-mediated end-joining. In plants, TLS is important for ultraviolet resistance.
From translesion synthesis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of POLH increase UV sensitivity? | POLH knockout cell line |
| Does a point mutation in PCNA affect TLS? | PCNA knock-in with ubiquitination site mutation |
| Can REV1 overexpression drive mutagenesis? | REV1 overexpression cell model |
| Does REV7 knockout impair TLS? | REV7 knockout cell line |
| Does tyrosine catabolism regulate TLS? | Metabolic gene knockout in ovarian cancer cells |
| Does USP1 inhibition sensitize to chemotherapy? | USP1 knockout or inhibitor-treated cells |
How to Study the translesion synthesis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Lesion reactivation assay | Efficiency of TLS bypass | In vitro with cell extracts |
| Co-immunoprecipitation | Protein-protein interactions | TLS complex assembly |
| Western blot | Protein expression and modifications | PCNA ubiquitination |
| CRISPR knockout screen | Gene essentiality and drug sensitivity | Identifying TLS targets |
| Mass spectrometry | Post-translational modifications | TLS regulation |
| Immunofluorescence | Subcellular localization | TLS polymerase recruitment |
| Flow cytometry | Cell cycle and apoptosis | TLS and chemotherapy response |
| RNA-seq | Transcriptional changes | TLS gene expression |
Assessing TLS activity
TLS activity can be measured using lesion-containing plasmid reactivation assays, in which a defined DNA lesion is bypassed by cellular extracts or purified proteins. These assays quantify the efficiency and fidelity of bypass.
Protein interaction studies
Co-immunoprecipitation, pull-down, and proximity ligation assays can map the protein assemblies involved in TLS, such as REV1-REV3L-REV7 complexes.
Post-translational modification analysis
Western blotting with modification-specific antibodies and mass spectrometry can detect PCNA ubiquitination and other TLS-related modifications.
CRISPR screening
Genome-wide CRISPR knockout screens can identify genes that modulate sensitivity to DNA-damaging agents, revealing TLS components as potential targets.
How CRISPR Can Be Used to Study GO:0019985 translesion synthesis
Knockout
CRISPR knockout of TLS genes such as POLH, REV1, or REV7 can reveal their roles in DNA damage tolerance and chemotherapy sensitivity [1,4]. For example, POLH knockout cells show increased UV sensitivity.
Point Mutation
Point mutations can be introduced into PCNA ubiquitination sites or polymerase catalytic residues to dissect their functions in TLS without completely abolishing protein expression.
Knock-in
Knock-in of tagged TLS polymerases (e.g., GFP or HA tags) allows real-time imaging and proteomic analysis of TLS complexes.
Overexpression
Overexpression of TLS genes such as REV1 or POLI can model the elevated TLS activity seen in some cancers and test whether it drives mutagenesis or drug resistance [3,4].
How EDITGENE Supports translesion synthesis Research
Researchers studying translesion synthesis-related genes often need to determine whether a candidate gene is causally involved in DNA damage tolerance, mutagenesis, or chemotherapy response. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell models for such studies.
Contact EDITGENE today to design your custom CRISPR model for translesion synthesis research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| POLN Knockout HEK293 Cell Line | EDJ-KQ1928 | Human | 353497 | Details Get a Quote |
| USP10 Knockout HEK293 Cell Line | EDJ-KQ2504 | Human | 9100 | Details Get a Quote |
| POLK Knockout HEK293 Cell Line | EDJ-KQ3042 | Human | 51426 | Details Get a Quote |
| POLH Knockout HEK293 Cell Line | EDJ-KQ3612 | Human | 5429 | Details Get a Quote |
| PRIMPOL Knockout HEK293 Cell Line | EDJ-KQ5011 | Human | 201973 | Details Get a Quote |
| PCLAF Knockout HEK293 Cell Line | EDJ-KQ6738 | Human | 9768 | Details Get a Quote |
| POLI Knockout HEK293 Cell Line | EDJ-KQ7331 | Human | 11201 | Details Get a Quote |
| ZBTB1 Knockout HEK293 Cell Line | EDJ-KQ7720 | Human | 22890 | Details Get a Quote |
| USP43 Knockout HEK293 Cell Line | EDJ-KQ7887 | Human | 124739 | Details Get a Quote |
| PARP10 Knockout HEK293 Cell Line | EDJ-KQ9460 | Human | 84875 | Details Get a Quote |
| REV1 Knockout HEK293 Cell Line | EDJ-KQ11102 | Human | 51455 | Details Get a Quote |
| FAAP20 Knockout HEK293 Cell Line | EDJ-KQ11713 | Human | 199990 | Details Get a Quote |
| REV1 Knockout HCT 116 Cell Line | EDJ-KQ18200 | Human | 51455 | Details Get a Quote |
| USP10 Knockout HCT 116 Cell Line | EDJ-KQ23099 | Human | 9100 | Details Get a Quote |
| USP10 Knockout HeLa Cell Line | EDJ-KQ23100 | Human | 9100 | Details Get a Quote |
Displaying Records 1 To 15 Of 54 Records
- 1
- 2
- Next Page »
Frequently Asked Questions About translesion synthesis
What is translesion synthesis?
Translesion synthesis is the replication of damaged DNA by synthesis across a lesion in the template strand, allowing DNA synthesis to continue beyond the lesion.
What genes are involved in translesion synthesis?
Key genes include POLH, POLI, POLK, REV1, REV3L, REV7, PCNA, and RAD18 [1,3,8].
Why is translesion synthesis important in cancer?
It contributes to mutagenesis and can confer resistance to DNA-damaging chemotherapy [1,4].
How is translesion synthesis regulated?
It is regulated by PCNA ubiquitination, protein assemblies, and post-translational modifications [3,8].
What are translesion synthesis inhibitors?
They are compounds that block TLS polymerases and are being developed as cancer chemotherapeutics.
Is translesion synthesis conserved in plants?
Yes, TLS in plants contributes to ultraviolet resistance and beyond.
What is the role of REV1 in translesion synthesis?
REV1 acts as a scaffold protein in TLS polymerase complexes.
How can I study translesion synthesis using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect TLS gene functions [1,4,8].
What diseases are linked to translesion synthesis defects?
Defects can lead to genome instability and cancer; TLS is also implicated in chemotherapy resistance [1,4].
What methods measure translesion synthesis activity?
Lesion reactivation assays, co-immunoprecipitation, and CRISPR screens are commonly used [1,3,4].
Conclusion
Translesion synthesis (GO:0019985) is a vital DNA damage tolerance mechanism that allows replication to bypass lesions at the cost of potential mutagenesis. Its regulation by protein assemblies and post-translational modifications makes it a rich area for research [3,8]. Therapeutically, TLS inhibitors are emerging as promising cancer chemotherapeutics. EDITGENE provides the CRISPR tools needed to create precise cell models for studying TLS genes and their roles in disease.
References
- 1. Shilkin ES et al.. 2020. Translesion DNA Synthesis and Carcinogenesis.. Biochemistry (Mosc) 85(4):425-435 PMID: 32569550
- 2. Sakamoto AN. 2019. Translesion Synthesis in Plants: Ultraviolet Resistance and Beyond.. Front Plant Sci 10:1208 PMID: 31649692
- 3. Arianna GA et al.. 2024. Protein Assemblies in Translesion Synthesis.. Genes (Basel) 15(7) PMID: 39062611
- 4. Patel SM et al.. 2021. Translesion synthesis inhibitors as a new class of cancer chemotherapeutics.. Expert Opin Investig Drugs 30(1):13-24 PMID: 33179552
- 5. Drogalis Beckham L et al.. 2025. Translesion synthesis and microhomology-mediated end-joining repair in trypanosomatids.. PLoS Negl Trop Dis 19(10):e0013626 PMID: 41171717
- 6. Li J et al.. 2023. Tyrosine catabolism enhances genotoxic chemotherapy by suppressing translesion DNA synthesis in epithelial ovarian cancer.. Cell Metab 35(11):2044-2059.e8 PMID: 37890478
- 7. Jansen JG et al.. 2015. Post-translesion synthesis repair.. Oncotarget 6(23):19342-3 PMID: 26305846
- 8. Ma X et al.. 2020. Regulation of translesion DNA synthesis in mammalian cells.. Environ Mol Mutagen 61(7):680-692 PMID: 31983077
