RecQ and RecJ process blocked replication forks prior to the resumption ofreplication in UV-irradiated Escherichia coli

The accurate recovery of replication following DNA damage and repair is cri tical for the maintenance of genomic integrity. In Escherichia coli, the re covery of replication following UV-induced DNA damage is dependent upon sev eral proteins in the recF pathway, including RecF, RecO, and RecR. Two othe r recF pathway proteins, the RecQ helicase and the RecJ exonuclease, have b een shown to affect the sites and frequencies at which illegitimate rearran gements occur following UV-induced DNA damage, suggesting that they also ma y function during the recovery of replication. We show here that RecQ and R ecJ process the nascent DNA at blocked replication forks prior to the resum ption of DNA synthesis. The processing involves selective degradation of th e nascent lagging DNA strand and it requires both RecQ and RecJ. We suggest that this processing may serve to lengthen the substrate that can be recog nized and stabilized by the RecA protein at the replication fork, thereby h elping to ensure the accurate recovery of replication after the obstructing lesion has been repaired.