Replication Fork Reversal
Replication Fork Reversal - Related Videos
02:37
Restarting Stalled Replication Forks
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2020
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
02:37
Restarting Stalled Replication Forks
0 Views •
2023
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
01:02
The DNA Replication Fork
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2020
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
01:02
The DNA Replication Fork
0 Views •
2023
An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...
07:27
Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
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Cited by 10 •
2010
The fate of the replisome following a collision with a head-on RNA polymerase (RNAP) is unknown. We find that the replisome stalls upon collision with a head-on RNAP, but resumes elongation after displacing the RNAP from DNA. Mfd promotes replication restart by facilitating displacement of the RNAP after the collision.
FAQs
The key structural change is reciprocal strand pairing: newly synthesized strands pair with each other, while parental strands reanneal. This arrangement produces a four-way junction in which the nascent DNA is no longer positioned only at the original fork. The resulting geometry helps connect replication interruption with downstream repair or controlled restart, rather than treating stalling as an isolated pause.
The remodeled junction can protect exposed DNA ends that arise when replication encounters damage or other obstacles. At the same time, it creates a DNA template that may support repair or controlled restart of replication. These functions explain why fork reversal can preserve genome integrity during replication stress instead of leaving interrupted DNA vulnerable to further instability.
Two conditions highlighted for replication fork reversal are DNA lesions and limited nucleotide availability. Lesions can obstruct polymerase movement directly, while insufficient nucleotides restrict DNA synthesis. Both situations create difficult replication conditions in which the fork may be remodeled, allowing the cell to manage stalled synthesis through protection, repair, or controlled restart.
Simple fork stalling describes an interruption in polymerase progress, whereas reversal describes a specific remodeling response to that interruption. The reversed structure pairs the newly synthesized strands and reanneals the parental strands, creating a four-way junction. This distinction matters because the remodeled intermediate can protect DNA ends and provide a template for repair or controlled restart.
Replication fork reversal provides a framework for understanding how cells tolerate replication stress without immediately losing chromosome integrity. Its study connects difficult replication conditions with DNA damage responses and mechanisms that preserve genome stability. These links make the process relevant to cancer biology, chromosome stability, and research on how cells respond when DNA synthesis is disrupted.
Because some therapies disrupt DNA replication, fork reversal is relevant to interpreting treatment-associated replication stress. The process can be considered alongside DNA lesions and limited nucleotide availability, both of which obstruct polymerase progress. Studying the resulting fork response may clarify whether DNA is protected, repaired, or routed toward controlled replication restart under those conditions.