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Updated: Jul 17, 2026
07:27
Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
Published on: April 29, 2010
Topological locking restrains replication fork reversal
Marta Fierro-Fernández1, Pablo Hernández, Dora B Krimer
1Centro de Investigaciones Biológicas, Departamento de Biología Celulor, del Desarrollo, Consejo Superior de Investigaciones Cientificas, Ramiro de Maeztu 9, 28040 Madrid, Spain.
Summary
Positive supercoiling prevents extensive DNA replication fork reversal. Holliday-like junctions form topological constraints, acting as a biological safety mechanism to protect DNA molecules during replication.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- DNA replication is a fundamental biological process.
- Replication fork reversal can lead to genomic instability.
- Understanding regulatory mechanisms is crucial for DNA integrity.
Purpose of the Study:
- To investigate the impact of positive supercoiling on DNA replication fork reversal.
- To elucidate the role of topological constraints in preventing fork regression.
Main Methods:
- Two-dimensional agarose gel electrophoresis
- Psoralen cross-linking
- Electron microscopy
- Analysis of bacterial DNA plasmid replication intermediates
Main Results:
- Positive supercoiling induces the formation of Holliday-like junctions at replication forks.
- These junctions create topological constraints that inhibit further fork regression.
- Replication intermediates are topologically locked, preventing extensive fork reversals.
Conclusions:
- The formation of Holliday-like junctions acts as a biological safety mechanism.
- This mechanism protects DNA molecules from detrimental extensive fork reversals.
- Topological locking is a key feature in maintaining DNA stability during replication.
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