RPA governs endonuclease switching during processing of Okazaki fragments in eukaryotes

Extensive work on the maturation of lagging strands during the replication of simian virus 40 DNA suggests that the initiator RNA primers of Okazaki fragments are removed by the combined action of two nucleases, RNase HI and Fen1, before the Okazaki fragments join1,2,3,4,5. Despite the well established in vitro roles of these two enzymes6, genetic analyses in yeast revealed that null mutants of RNase HI and/or Fen1 are not lethal7,8,9,...