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Author Spotlight: Unraveling the Dynamics of Eukaryotic DNA Replication Through Single-Molecule Visualization
Published on: September 27, 2024
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Direct visualization of transcription-replication conflicts reveals post-replicative DNA:RNA hybrids.
Henriette Stoy1, Katharina Zwicky1, Danina Kuster1
1Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
Nature Structural & Molecular Biology
|March 2, 2023
Summary
Transcription-replication collisions (TRCs) can cause genome instability. This study visualizes R-loops, revealing DNA:RNA hybrids behind replication forks, which slow fork progression and delay DNA maturation.
Area of Science:
- Genetics
- Molecular Biology
- Genomics
Background:
- Transcription-replication collisions (TRCs) are a major source of genome instability.
- R-loops have been implicated in TRCs and replication fork obstruction, but mechanisms remain unclear.
Purpose of the Study:
- To directly visualize and quantify R-loops during TRCs.
- To elucidate the mechanisms by which R-loops interfere with replication.
Main Methods:
- Electron microscopy (EM) for direct visualization of R-loops.
- Immuno-labeling combined with EM for locus-specific TRCs in bacteria.
- Single-molecule R-loop measurement.
- Comet assays on nascent DNA.
Main Results:
- DNA:RNA hybrids frequently accumulate behind replication forks during head-on TRCs.
- These post-replicative hybrids are associated with replication fork slowing and reversal.
- Nascent DNA maturation is significantly delayed in conditions linked to R-loop accumulation.
- R-loop bypass by replication forks precedes subsequent interference events.
Conclusions:
- TRC-associated replication interference involves events occurring after replication fork bypass of R-loops.
- Direct visualization and molecular tools confirm the role of R-loops in genome instability during TRCs.
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