Open AccessDisease-associated DNA2 nuclease–helicase protects cells from lethal chromosome under-replication
Author(s) -
Benoît Falquet,
Gizem Ölmezer,
Franz Enkner,
Dominique Klein,
Kiran Challa,
Rowin Appanah,
Susan M. Gasser,
Ulrich Rass
Publication year - 2020
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkaa524
Subject(s) - biology , helicase , okazaki fragments , g2 m dna damage checkpoint , control of chromosome duplication , homologous recombination , microbiology and biotechnology , dna replication , dna re replication , dna repair , dna damage , nuclease , dna , replication protein a , genetics , eukaryotic dna replication , cell cycle checkpoint , cell cycle , cell , dna binding protein , gene , transcription factor , rna
DNA2 is an essential nuclease-helicase implicated in DNA repair, lagging-strand DNA synthesis, and the recovery of stalled DNA replication forks (RFs). In Saccharomyces cerevisiae, dna2Δ inviability is reversed by deletion of the conserved helicase PIF1 and/or DNA damage checkpoint-mediator RAD9. It has been suggested that Pif1 drives the formation of long 5'-flaps during Okazaki fragment maturation, and that the essential function of Dna2 is to remove these intermediates. In the absence of Dna2, 5'-flaps are thought to accumulate on the lagging strand, resulting in DNA damage-checkpoint arrest and cell death. In line with Dna2's role in RF recovery, we find that the loss of Dna2 results in severe chromosome under-replication downstream of endogenous and exogenous RF-stalling. Importantly, unfaithful chromosome replication in Dna2-mutant cells is exacerbated by Pif1, which triggers the DNA damage checkpoint along a pathway involving Pif1's ability to promote homologous recombination-coupled replication. We propose that Dna2 fulfils its essential function by promoting RF recovery, facilitating replication completion while suppressing excessive RF restart by recombination-dependent replication (RDR) and checkpoint activation. The critical nature of Dna2's role in controlling the fate of stalled RFs provides a framework to rationalize the involvement of DNA2 in Seckel syndrome and cancer.