Fork reversal (or fork regression) occurs when a replication fork faces genotoxic stress. Uncoupling of leading and lagging strand synthesis results in the accumulation of single-stranded DNA (ssDNA) at the replication junction (uncoupled fork; bottom panel).
What is an arrested Fork reversal?
Arrested forks are unstable structures that can give rise to collapse and rearrange if they are not properly processed and restarted. Replication fork reversal is a critical protective mechanism in higher eukaryotic cells in response to replication stress, in which forks reverse their direction to form a Holliday junction-like structure.
Can a reversal of a replication fork prevent replisome collision?
The reversal of the first replication fork reaching the pausing or termination region could enable the complete replication of the termination region by the second fork, thereby preventing collision of the two converging replisomes ( Fig. 4a ).
What is a regressed arm of a reversed replication fork?
The regressed arm of a reversed replication fork resembles a one-ended double-stranded break (DSB) and must be properly protected to prevent nuclease cleavage. However, the molecular determinants required to protect the integrity of regressed arms until forks are restarted are unknown.
