GO:0000109 nucleotide-excision repair complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0000109 (nucleotide-excision repair complex) is a cellular component defined as any complex formed of proteins that act in nucleotide-excision repair.
• The term includes the UvrBC complex (UvrB-UvrC complex) and the core pre-incision and incision complexes of eukaryotic NER.
• Key protein components include XPA, XPC, TFIIH, XPG, XPF-ERCC1, RPA, and the UV-DDB complex, which assemble in a stepwise manner.
• Defects in NER complex components cause xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy, and are linked to cancer and ageing.
• CRISPR knockout, point mutation, knock-in, and overexpression models are essential to dissect NER complex assembly and function.
• EDITGENE provides custom cell models and CRISPR library screening to study nucleotide-excision repair complex genes.
Description
The nucleotide-excision repair complex (GO:0000109) is a cellular component comprising proteins that carry out nucleotide-excision repair (NER), a versatile DNA repair pathway that removes a wide range of helix-distorting lesions, including UV-induced cyclobutane pyrimidine dimers and 6-4 photoproducts, as well as bulky chemical adducts. This complex is not a single static entity but a dynamic assembly of factors that recognize damage, verify the lesion, incise the damaged strand, and facilitate repair synthesis. Understanding its composition and assembly is fundamental to molecular biology because NER is essential for genome stability, and its dysfunction leads to severe human disorders such as xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy, as well as increased cancer predisposition and accelerated ageing. Recent structural and live-cell studies have refined our view of how NER complexes are organized and how they transition between damage recognition and incision. The term GO:0000109 encompasses both the prokaryotic UvrBC complex and the eukaryotic pre-incision and incision complexes, reflecting the evolutionary conservation of the core NER machinery. For researchers, this GO term provides a standardized way to annotate proteins and complexes involved in NER, facilitating functional genomics, proteomics, and disease modeling.
nucleotide-excision repair complex At A Glance
| GO ID | GO:0000109 |
|---|---|
| GO term | nucleotide-excision repair complex |
| Ontology | cellular_component |
| Synonym | UvrBC complex, UvrB-UvrC complex |
| Definition | Any complex formed of proteins that act in nucleotide-excision repair. |
| Major function | Damage recognition, verification, dual incision, and repair synthesis during nucleotide-excision repair. |
| Related pathways | Nucleotide-excision repair (NER), transcription-coupled NER (TC-NER), global genome NER (GG-NER). |
| Key components | XPA, XPC, TFIIH, XPG, XPF-ERCC1, RPA, UV-DDB, and bacterial UvrB/UvrC. |
| Disease relevance | Xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, cancer predisposition, and premature ageing. |
What Is GO:0000109?
According to the Gene Ontology, GO:0000109 (nucleotide-excision repair complex) is defined as any complex formed of proteins that act in nucleotide-excision repair. This cellular component includes the UvrBC complex (also known as UvrB-UvrC complex) in bacteria and the analogous eukaryotic complexes that assemble at sites of DNA damage, such as the pre-incision complex containing XPA, RPA, TFIIH, XPG, and XPF-ERCC1. The term captures the dynamic and heterogeneous nature of NER complexes, which are assembled transiently on damaged DNA and disassembled after repair.
Why Is nucleotide-excision repair complex Important in Cell Biology?
The nucleotide-excision repair complex is critically important because it safeguards the genome against a constant barrage of DNA-damaging agents, and its failure directly causes human disease. Mutations in NER genes lead to xeroderma pigmentosum, characterized by extreme UV sensitivity and a thousand-fold increased risk of skin cancer, as well as Cockayne syndrome and trichothiodystrophy, which involve developmental and neurological abnormalities. Beyond rare genetic disorders, NER activity influences cancer therapy outcomes, as platinum-based chemotherapies and other DNA-damaging agents rely on NER status for efficacy. Moreover, NER decline is associated with ageing, and understanding the complex's assembly and regulation offers opportunities for therapeutic intervention. The dynamic nature of NER complexes, as revealed by live-cell imaging and structural studies, underscores the need for precise experimental models to dissect their function.
• Prevents mutations and cancer by removing UV-induced and chemical DNA adducts.
• Defects cause xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy.
• Influences response to platinum-based chemotherapies and other DNA-damaging treatments.
• Plays a role in ageing and age-related decline in genome maintenance.
• Provides a model for studying dynamic multiprotein complex assembly on DNA.
• Is conserved from bacteria to humans, enabling comparative studies.
• Serves as a target for CRISPR screens to identify novel NER factors.
• Helps understand transcription-coupled repair and its link to RNA polymerase II stalling.
• Offers insights into protein-protein interactions and structural biology of repair machines.
• Guides development of experimental models for precision medicine in DNA repair.
Structure and Composition of nucleotide-excision repair complex
Damage recognition and initial assembly
In simple terms: The cell first finds the DNA damage and starts building a repair machine around it.
In global genome NER, the UV-DDB complex (DDB1-DDB2) and XPC-RAD23B recognize helix-distorting lesions, while in transcription-coupled NER, stalled RNA polymerase II recruits CSB and CSA. The initial recognition leads to the recruitment of TFIIH, a multi-subunit complex containing XPB and XPD helicases, which unwinds DNA around the damage and verifies the lesion. This step is critical for assembling the pre-incision complex, and defects in recognition factors cause xeroderma pigmentosum group C or Cockayne syndrome.
Pre-incision complex formation
In simple terms: Several proteins come together to form a stable platform that will cut the damaged DNA.
After damage verification, XPA, RPA, and XPG join the TFIIH complex to form the pre-incision complex. XPA helps position the repair machinery, while RPA binds the undamaged single-stranded DNA opposite the lesion, stabilizing the open complex. The structure of this pre-incision complex has been resolved by cryo-electron microscopy, revealing a dynamic arrangement that coordinates the two nucleases, XPG and XPF-ERCC1, for subsequent incision. Protein-protein interactions within this complex are essential for its integrity and function.
Dual incision and repair synthesis
In simple terms: The repair machine cuts out the damaged piece and fills the gap with new DNA.
The endonucleases XPG and XPF-ERCC1 catalyze incisions on the 3' and 5' sides of the lesion, respectively, excising a 22-30 nucleotide fragment. The resulting gap is filled by DNA polymerase delta or epsilon, with PCNA and RFC, and sealed by DNA ligase I. This dual incision mechanism is highly coordinated to avoid aberrant cuts, and structural studies have illuminated how the nuclease active sites are positioned. The bacterial UvrBC complex performs an analogous dual incision, with UvrB and UvrC generating the cuts.
Complex disassembly and turnover
In simple terms: After repair, the machine falls apart so the DNA can return to normal.
Following repair synthesis and ligation, the NER complex disassembles, and its components are recycled for subsequent repair events. Live-cell imaging has shown that NER factors are dynamically exchanged at damage sites, with residence times ranging from seconds to minutes. This turnover is regulated by post-translational modifications and protein degradation pathways, ensuring that repair is efficient and not persistently engaged. The dynamic nature of the complex is a key area of current research.
Key Genes Involved in GO:0000109 nucleotide-excision repair complex
The following genes encode core components of the nucleotide-excision repair complex and are frequently studied in NER research.
| Gene | Major Role | Research Relevance |
|---|---|---|
| XPA | Damage verification and positioning of repair factors | Mutations cause xeroderma pigmentosum group A; key for pre-incision complex assembly |
| XPC | Primary damage sensor in global genome NER | Mutations cause XP group C; target for studying GG-NER initiation |
| DDB1 | Component of UV-DDB complex, damage recognition | Involved in GG-NER and ubiquitination; linked to cancer |
| DDB2 | Component of UV-DDB complex, binds UV lesions | Mutations cause XP group E; important for damage recognition |
| ERCC1 | Catalytic subunit with XPF for 5' incision | Defects cause XP and Cockayne syndrome; biomarker for platinum therapy |
| ERCC2 (XPD) | TFIIH helicase for damage verification | Mutations cause XP, TTD, and CS; target for structural studies |
| ERCC3 (XPB) | TFIIH helicase for DNA unwinding | Mutations cause XP and TTD; essential for transcription and repair |
| ERCC4 (XPF) | Nuclease for 5' incision | Mutations cause XP and progeroid syndromes; interaction with ERCC1 |
| ERCC5 (XPG) | Nuclease for 3' incision | Mutations cause XP and CS; structural insights into incision |
| CUL4A | Ubiquitin ligase in UV-DDB complex | Regulates damage recognition; potential cancer target |
| RPA1 | Binds single-stranded DNA during NER | Essential for pre-incision complex stability |
| RPA2 | Subunit of RPA complex | Phosphorylated in response to DNA damage; marker for NER activity |
| CETN2 | Centrin-2, involved in XPC regulation | Modulates GG-NER; less studied but emerging |
| GTF2H1 | TFIIH subunit p62 | Core TFIIH component; mutations affect repair and transcription |
| GTF2H2 | TFIIH subunit p44 | Mutations cause TTD; important for TFIIH stability |
| CKN1 (CSA) | TC-NER factor | Mutations cause Cockayne syndrome; links transcription to repair |
| ERCC6 (CSB) | TC-NER factor, recruits repair to stalled RNAPII | Mutations cause CS; key for transcription-coupled repair |
| LIG1 | DNA ligase I for sealing repair patch | Final step of NER; mutations cause immunodeficiency |
How Is nucleotide-excision repair complex Regulated?
The nucleotide-excision repair complex is regulated at multiple levels, including post-translational modifications, protein-protein interactions, and chromatin context. Phosphorylation of RPA and other factors modulates complex assembly and activity. Ubiquitination of XPC and DDB2 by CUL4A-DDB1 regulates damage recognition and turnover. Transcription-coupled NER is tightly linked to RNA polymerase II stalling and requires CSA and CSB for recruitment of downstream factors. Additionally, the complex's activity is influenced by the 3D genome organization, as recent studies show that aflatoxin-induced damage repair is affected by chromatin architecture. Helicases such as XPB and XPD within TFIIH are regulated by their interactions with other subunits and by ATP binding.
nucleotide-excision repair complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| XPA | Xeroderma pigmentosum group A | Knockout in keratinocytes or fibroblasts; UV sensitivity assays |
| XPC | Xeroderma pigmentosum group C | Knockout in melanocytes; global genome NER reporter |
| ERCC2 (XPD) | Xeroderma pigmentosum, trichothiodystrophy | Point mutation knock-in in HEK293; TFIIH assembly studies |
| ERCC6 (CSB) | Cockayne syndrome | Knockout in neurons; transcription-coupled repair assays |
| ERCC1 | Xeroderma pigmentosum, cancer therapy resistance | Knockout in cancer cell lines; platinum sensitivity |
Xeroderma pigmentosum and cancer predisposition
Mutations in NER genes such as XPA, XPC, ERCC2, and ERCC5 cause xeroderma pigmentosum, an autosomal recessive disorder characterized by severe photosensitivity and a greater than 1000-fold increased risk of skin cancer. The nucleotide-excision repair complex fails to remove UV-induced lesions, leading to mutations that drive carcinogenesis. This link underscores the importance of NER complex integrity in cancer prevention.
Cockayne syndrome and trichothiodystrophy
Defects in transcription-coupled NER factors, such as CSA and CSB, cause Cockayne syndrome, which involves growth failure, neurological degeneration, and premature ageing without elevated cancer risk. Trichothiodystrophy, caused by mutations in TFIIH subunits like ERCC2 and GTF2H2, leads to brittle hair, ichthyosis, and developmental abnormalities. These disorders highlight the complex's role in both repair and transcription.
Ageing and neurodegeneration
Decline in NER capacity is associated with ageing, and defects in NER complex components can lead to progressive neurodegeneration, as seen in Cockayne syndrome and some xeroderma pigmentosum cases. Oxidative DNA damage and transcription-blocking lesions accumulate with age, and inefficient repair contributes to cellular senescence. Understanding NER complex regulation may provide insights into age-related diseases.
Therapeutic implications in cancer treatment
NER status influences the response to platinum-based chemotherapies, as high NER activity can remove platinum-DNA adducts and confer resistance. Conversely, low NER activity may sensitize tumors to these agents. Targeting NER complex components, such as ERCC1 or XPF, is an active area of drug development. Additionally, NER defects can be exploited with synthetic lethality approaches.
From nucleotide-excision repair complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of XPA abolish NER complex assembly? | XPA knockout cell line (e.g., HeLa or fibroblasts) |
| How does a patient mutation in ERCC2 affect TFIIH function? | Point mutation knock-in of ERCC2 in HEK293 cells |
| Can we visualize NER complex dynamics in live cells? | Tagged knock-in of XPC or XPA with fluorescent protein |
| Does overexpression of XPC enhance repair capacity? | XPC overexpression in keratinocytes |
| What genes are essential for NER in a genome-wide screen? | CRISPR knockout library screening in UV-sensitive cells |
| How does chromatin context affect NER complex recruitment? | Knock-in of tagged XPA in cells with defined chromatin marks |
How to Study the nucleotide-excision repair complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging (FRAP, tracking) | Dynamic assembly and turnover of NER factors | Studying real-time complex dynamics at damage sites |
| Cryo-EM | High-resolution structure of NER complexes | Understanding pre-incision complex architecture |
| Unscheduled DNA synthesis (UDS) | Overall NER activity in cells | Diagnosing xeroderma pigmentosum and evaluating KO models |
| ChIP-seq | Genome-wide binding of NER proteins | Mapping repair hotspots and chromatin effects |
| Immunoprecipitation-mass spectrometry | Protein-protein interactions and modifications | Identifying novel NER complex components |
| CRISPR knockout screen | Genes required for UV resistance | Discovering new NER factors |
| In vitro incision assay | Dual incision activity | Mechanistic studies with purified proteins |
| Comet assay | DNA damage and repair kinetics | Quantifying lesion removal in cell models |
Live-cell imaging of NER complex dynamics
Fluorescence microscopy of cells expressing fluorescently tagged NER proteins, such as XPC-GFP or XPA-mCherry, allows real-time visualization of complex assembly at damage sites. Techniques like fluorescence recovery after photobleaching (FRAP) and single-molecule tracking reveal residence times and exchange rates. This approach has shown that NER factors are highly dynamic and assemble in a stepwise manner.
Structural biology of NER complexes
Cryo-electron microscopy and X-ray crystallography have provided near-atomic resolution structures of the pre-incision complex and TFIIH. These methods reveal how proteins interact and coordinate dual incision. Structural studies of bacterial UvrBC complex also inform mechanism. Complementary crosslinking mass spectrometry maps protein-protein interfaces.
Functional assays for NER activity
Unscheduled DNA synthesis (UDS) and host-cell reactivation assays measure overall NER capacity in cells. In vitro reconstitution with purified proteins allows dissection of individual steps. Comet assays and ELISA-based damage detection quantify specific lesions. These assays are used to diagnose NER-deficient patient cells and evaluate experimental models.
Genomic and proteomic approaches
Chromatin immunoprecipitation followed by sequencing (ChIP-seq) maps NER factor binding genome-wide, revealing repair hotspots and the influence of 3D genome organization. Proteomics, including immunoprecipitation-mass spectrometry, identifies novel interactors and post-translational modifications. CRISPR screens coupled with UV sensitivity readouts identify genes required for NER complex function.
How CRISPR Can Be Used to Study GO:0000109 nucleotide-excision repair complex
Knockout
CRISPR knockout of core NER genes such as XPA, XPC, or ERCC1 creates cell models that are hypersensitive to UV and chemical DNA-damaging agents. These knockouts are invaluable for confirming the essentiality of a gene in the nucleotide-excision repair complex and for dissecting pathway steps. For example, XPA knockout abolishes pre-incision complex assembly and reduces UDS. EDITGENE provides custom knockout cell lines in various backgrounds to study NER complex function.
Point Mutation
Knock-in of patient-specific point mutations, such as those in ERCC2 (XPD) or ERCC5 (XPG), allows researchers to study the molecular basis of xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy. These models reveal how single amino acid changes affect protein stability, interactions, and catalytic activity within the NER complex. Point mutation models are essential for genotype-phenotype correlations and for testing targeted therapies.
Knock-in
Tagged knock-in of NER genes with fluorescent or affinity tags (e.g., GFP, HA) enables live-cell imaging and proteomic analysis of the nucleotide-excision repair complex. Knock-in of reporter cassettes can also create damage-responsive transcriptional reporters. These models preserve endogenous regulation and are ideal for studying dynamic assembly and disassembly. EDITGENE offers precise knock-in services for NER genes.
Overexpression
Overexpression of NER factors, such as XPC or XPA, can enhance repair capacity and protect cells from DNA damage. Conversely, overexpression of dominant-negative mutants can disrupt complex function. Overexpression models are useful for biochemical purification of NER complexes and for studying stoichiometry. They also help identify rate-limiting steps in repair.
How EDITGENE Supports nucleotide-excision repair complex Research
Researchers studying nucleotide-excision repair complex-related genes often need to determine whether a candidate gene is causally involved in DNA repair, how mutations affect complex assembly, and whether modulating its activity alters cellular sensitivity to DNA-damaging agents. EDITGENE provides a comprehensive suite of CRISPR-based cell model services to address these questions with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for nucleotide-excision repair complex research.
Frequently Asked Questions About nucleotide-excision repair complex
What is the nucleotide-excision repair complex?
The nucleotide-excision repair complex (GO:0000109) is a cellular component defined as any complex formed of proteins that act in nucleotide-excision repair, including the UvrBC complex and eukaryotic pre-incision and incision complexes.
What genes are involved in nucleotide-excision repair complex?
Key genes include XPA, XPC, DDB1, DDB2, ERCC1, ERCC2 (XPD), ERCC3 (XPB), ERCC4 (XPF), ERCC5 (XPG), RPA1, RPA2, GTF2H1, GTF2H2, ERCC6 (CSB), and ERCC8 (CSA).
What is the function of GO:0000109?
GO:0000109 represents the protein complexes that recognize DNA damage, verify lesions, incise the damaged strand, and facilitate repair synthesis during nucleotide-excision repair.
How is the nucleotide-excision repair complex assembled?
It assembles in a stepwise manner: damage recognition by UV-DDB and XPC, recruitment of TFIIH, formation of the pre-incision complex with XPA, RPA, and XPG, followed by XPF-ERCC1 recruitment and dual incision.
What diseases are linked to defects in the nucleotide-excision repair complex?
Defects cause xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy, and are associated with cancer predisposition and premature ageing.
How can I study the nucleotide-excision repair complex in the lab?
Common methods include live-cell imaging of tagged NER proteins, cryo-EM, unscheduled DNA synthesis assays, ChIP-seq, and CRISPR knockout screens.
What is the UvrBC complex?
The UvrBC complex is a bacterial nucleotide-excision repair complex composed of UvrB and UvrC proteins that performs dual incision around DNA lesions; it is a synonym for GO:0000109.
Why is the nucleotide-excision repair complex important in cancer?
NER activity determines sensitivity to platinum-based chemotherapies and other DNA-damaging agents; high NER can confer resistance, while defects increase cancer risk.
What CRISPR models are available for NER research?
EDITGENE offers knockout, point mutation knock-in, tagged knock-in, overexpression cell models, and CRISPR library screening for NER genes.
How does transcription-coupled NER differ from global genome NER?
Transcription-coupled NER specifically repairs lesions that block RNA polymerase II and requires CSA and CSB, while global genome NER surveys the entire genome and relies on XPC and UV-DDB.
Conclusion
The nucleotide-excision repair complex (GO:0000109) is a dynamic and essential cellular machine that protects the genome from a wide range of DNA lesions. Its stepwise assembly and coordinated dual incision mechanism are critical for preventing mutations and disease. Defects in its components cause severe human disorders, and its activity influences cancer therapy outcomes. Continued research using advanced CRISPR models and structural techniques will further illuminate its regulation and therapeutic potential. EDITGENE is committed to supporting this research with custom cell models and screening services.
References
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- 6. D'Souza A et al.. 2024. Protein-protein interactions in the core nucleotide excision repair pathway.. DNA Repair (Amst) 141:103728 PMID: 39029374
- 7. Wu Y et al.. 2024. Nucleotide excision repair of aflatoxin-induced DNA damage within the 3D human genome organization.. Nucleic Acids Res 52(19):11704-11719 PMID: 39258558
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