chi sequences switch the RecBCD helicase-nuclease complex from degradative to replicative modes during the completion of DNA replication.

Accurately completing DNA replication when two forks converge is essential to genomic stability. The RecBCD helicase-nuclease complex plays a central role in completion by promoting resection and joining of the excess DNA created when replisomes converge. chi sequences alter RecBCD activity and localize with crossover hotspots during sexual events in bacteria, yet their functional role during chromosome replication remains unknown.