TY - JOUR T1 - The non-homologous end joining factor Ku orchestrates replication fork resection and fine-tunes Rad51-mediated fork restart JF - bioRxiv DO - 10.1101/162677 SP - 162677 AU - Ana Teixeira-Silva AU - Anissia Ait Saada AU - Ismail Iraqui AU - Marina Charlotte Nocente AU - Karine Fréon AU - Julien Hardy AU - Sarah Lambert Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/07/12/162677.abstract N2 - Replication requires Homologous Recombination (HR) to stabilize and restart terminally-arrested forks. HR-mediated fork processing requires single stranded DNA (ssDNA) gaps and not necessarily Double Strand Breaks. We used genetic and molecular assays to investigate fork-resection and restart at dysfunctional, unbroken forks in Schizosaccharomyces pombe. We found that fork-resection is a two-step process coordinated by the non-homologous end joining factor Ku. An initial resection mediated by MRN/Ctp1 removes Ku from terminally-arrested forks, generating ~ 110 bp sized gaps obligatory for subsequent Exo1-mediated long-range resection and replication restart. The lack of Ku results in slower fork restart, excessive resection, and impaired RPA recruitment. We propose that terminally-arrested forks undergo fork reversal, providing a single DNA end for Ku binding which primes RPA-coated ssDNA. We uncover an unprecedented role for Ku in orchestrating resection of unbroken forks and in fine-tuning HR-mediated replication restart.Ku orchestrates a two-steps DNA end-resection of terminally-arrested and unbroken forksMRN/Ctp1 removes Ku from terminally-arrested forks to initiate fork-resectiona ~110 bp sized ssDNA gap is sufficient and necessary to promote fork restart.The lack of Ku decreases ssDNA RPA-coating, and slows down replication fork restart. ER -