Processing of eukaryotic Okazaki fragments by redundant nucleases can be uncoupled from ongoing DNA replication in vivo.

Prior to ligation, each Okazaki fragment synthesized on the lagging strand in eukaryotes must be nucleolytically processed. Nuclease cleavage takes place in the context of 5' flap structures generated via strand-displacement synthesis by DNA polymerase delta. At least three DNA nucleases: Rad27 (Fen1), Dna2 and Exo1, have been implicated in processing Okazaki fragment flaps.

Pif1-family helicases cooperatively suppress widespread replication-fork arrest at tRNA genes.

Saccharomyces cerevisiae expresses two Pif1-family helicases-Pif1 and Rrm3-which have been reported to play distinct roles in numerous nuclear processes. Here, we systematically characterized the roles of Pif1 helicases in replisome progression and lagging-strand synthesis in S. cerevisiae.