RAD52 prevents accumulation of RAD51 and Polα-dependent DNA gaps at perturbed replication forks

Replication gaps can arise as a consequence of perturbed DNA replication, and their accumulation might undermine the stability of the genome. Loss of RAD52, a protein involved in the regulation of fork reversal, promotes accumulation of parental ssDNA gaps during replication perturbation. Here, we demonstrate that this is due to the engagement of Polα downstream of the extensive degradation of perturbed replication forks after their reversal and is not dependent on PrimPol. Polα is hyper-recruited at parental ssDNA in the absence of RAD52, and this recruitment is dependent on fork reversal enzymes and RAD51. Of note, we report that the interaction between Polα and RAD51 is stimulated by RAD52 inhibition, and Polα-dependent gap accumulation requires formation of the RAD51 nucleoprotein filaments. Our data indicate that the RAD51/Polα-dependent repriming is essential to support fork progression, limit DNA damage and improve viability of RAD52-deficient cells when replication is perturbed. Altogether, this study shows that RAD51/Polα-dependent repriming is a genuine fork recovery mechanism activated to overcome loss of RAD52 function at replication forks.