Human DNA polymerase eta promotes DNA synthesis from strand invasion intermediates of homologous recombination.
Stalled replication forks pose a serious threat to genome integrity. To overcome the catastrophic consequences associated with fork demise, translesion synthesis (TLS) polymerases such as poleta promote DNA synthesis past lesions. Alternatively, a stalled fork may collapse and undergo repair by homologous recombination. By using fractionated cell extracts and purified recombinant proteins, we show that poleta extends DNA synthesis from D loop recombination intermediates in which an invading strand serves as the primer. Extracts from XP-V cells, which are defective in poleta, exhibit severely reduced D loop extension activity. The D loop extension activity of poleta is unusual, as this reaction cannot be promoted by the replicative DNA polymerase delta or by other TLS polymerases such as poliota. Moreover, we find that poleta interacts with RAD51 recombinase and RAD51 stimulates poleta-mediated D loop extension. Our results indicate a dual function for poleta at stalled replication forks: the promotion of translesion synthesis and the reinitiation of DNA synthesis by homologous recombination repair.
McIlwraith
Michael J
MJ
Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, Herts, EN6 3LD, United Kingdom.
Mcllwraith
Michael J
MJ
Vaisman
Alexandra
A
Liu
Yilun
Y
Fanning
Ellen
E
Woodgate
Roger
R
West
Stephen C
SC
D002457:Cell Extracts; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis*; D004260:DNA Repair / Q000502:physiology; D004261:DNA Replication / Q000502:physiology; D004277:DNA, Single-Stranded / Q000235:genetics* / Q000528:radiation effects; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D008957:Models, Genetic; D051135:Rad51 Recombinase / Q000378:metabolism; D011995:Recombination, Genetic; D000099270:Y-Family DNA Polymerases
D002457:Cell Extracts; D004247:DNA; D004277:DNA, Single-Stranded; D004259:DNA-Directed DNA Polymerase; D051135:Rad51 Recombinase; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases