Pre-incision structures reveal principles of DNA nucleotide excision repair
Article Date = 2026-02-11
Article URL = https://www.nature.com/articles/s41586-026-10122-5
Article Title = Pre-incision structures reveal principles of DNA nucleotide excision repair
Article Image = (not provided)
Summary
This Nature paper presents high-resolution structural snapshots of the nucleotide excision repair (NER) pre-incision complex. Using cryo-EM and complementary biochemical data, the authors map how core NER factors — XPC, TFIIH (including the XPD helicase), XPA, RPA and the endonucleases ERCC1–XPF and XPG — assemble on damaged DNA before the dual incision step. The structures reveal the positioning and conformational changes that govern lesion verification, DNA unwinding and the choreography that primes the system for precise 5′ and 3′ cuts. The work links structural states to mechanistic steps and helps explain how particular mutations disrupt repair and cause disease.
Key Points
- High-resolution pre-incision complexes visualise how damage-recognition (XPC) hands over to the TFIIH helicase for lesion verification.
- TFIIH activation and XPD engagement with damaged DNA are shown in distinct conformational states that explain directional scanning and verification.
- XPA and RPA are positioned to stabilise unwound single-stranded DNA and to recruit ERCC1–XPF and XPG in the correct orientation for dual incision.
- The structures capture ordered conformational changes that coordinate verification, DNA unwinding and nuclease access — preventing premature cleavage.
- Mapping of interaction surfaces clarifies how disease-associated mutations disrupt specific assemblies, offering molecular explanations for xeroderma pigmentosum and Cockayne syndrome phenotypes.
- Combining cryo-EM with prior biochemical and genetic data builds a dynamic model for the stepwise assembly and activation of the NER machinery.
Content summary
The authors used cryo-electron microscopy to determine multiple states of the NER pre-incision complex, capturing the sequence from lesion recognition to a nuclease-ready assembly. The data show how XPC recognises distorted DNA and assists TFIIH loading; how TFIIH (and its XPD helicase) translocates and verifies the lesion; and how XPA and RPA stabilise the opened bubble and organise recruitment of ERCC1–XPF and XPG. Structural snapshots reveal interfaces and conformational transitions that gate nuclease activity until verification is complete. The paper ties structural features to functional assays and known pathogenic variants, strengthening the link between mechanism and disease.
The authors compare their maps with earlier biochemical reconstitutions and recent structures of TFIIH and nucleases, synthesising a coherent pre-incision choreography: damage sensing → TFIIH engagement and verification → local unwinding and RPA binding → recruitment/activation of nucleases → dual incision. This clarifies long-standing questions about coordination and directionality in human NER.
Context and relevance
NER is a fundamental DNA-repair pathway that removes bulky lesions from the genome; failures cause severe human disorders and raise cancer risk. Structural insight into the pre-incision complex fills a critical gap between biochemical models and molecular mechanism. For researchers in DNA repair, structural biology and medical genetics, these findings refine how we interpret pathogenic variants and guide hypotheses for targeted interventions. The work also informs on general principles of multi-protein assembly, verification checkpoints and regulated nuclease access that apply beyond NER.
Why should I read this?
Short version: if you care about how cells find and remove nasty DNA damage, this paper shows the actual molecular choreography — who stands where and who waits for permission before the cut. It’s packed with neat structural snapshots that save you hours of piecing together older biochemical puzzles.
Author style
Punchy: this is a must-read for people who want the molecular blueprint of human NER. The structures don’t just look pretty — they explain how verification prevents an accidental snip and why specific mutations are catastrophic. If you work on DNA repair, cancer genetics or structural enzymology, the detailed maps here are directly useful.