Abstract
DNA crosslinks block DNA replication and are repaired by the Fanconi anaemia pathway. The FANCD2-FANCI (D2-I) protein complex is central to this process as it initiates repair by coordinating DNA incisions around the lesion1. However, D2-I is also known to have a more general role in DNA repair and in protecting stalled replication forks from unscheduled degradation2-4. At present, it is unclear how DNA crosslinks are recognized and how D2-I functions in replication fork protection. Here, using single-molecule imaging, we show that D2-I is a sliding clamp that binds to and diffuses on double-stranded DNA. Notably, sliding D2-I stalls on encountering single-stranded-double-stranded (ss-ds) DNA junctions, structures that are generated when replication forks stall at DNA lesions5. Using cryogenic electron microscopy, we determined structures of D2-I on DNA that show that stalled D2-I makes specific interactions with the ss-dsDNA junction that are distinct from those made by sliding D2-I. Thus, D2-I surveys dsDNA and, when it reaches an ssDNA gap, it specifically clamps onto ss-dsDNA junctions. Because ss-dsDNA junctions are found at stalled replication forks, D2-I can identify sites of DNA damage. Therefore, our data provide a unified molecular mechanism that reconciles the roles of D2-I in the recognition and protection of stalled replication forks in several DNA repair pathways.
| Original language | English |
|---|---|
| Pages (from-to) | 1165-1173 |
| Number of pages | 9 |
| Journal | Nature |
| Volume | 632 |
| Issue number | 8027 |
| DOIs | |
| Publication status | Published - Aug 2024 |
Keywords
- Animals
- Female
- Humans
- Cell Extracts
- Cryoelectron Microscopy
- Diffusion
- DNA/chemistry
- DNA Damage
- DNA Repair
- DNA Replication
- DNA, Single-Stranded/chemistry
- Fanconi Anemia Complementation Group D2 Protein/chemistry
- Fanconi Anemia Complementation Group Proteins/chemistry
- Models, Molecular
- Protein Binding
- Single Molecule Imaging
- Xenopus laevis