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Multiple Rad5 activities mediate sister chromatid recombination to bypass DNA damage at stalled replication forks

Eugen C Minca1, David Kowalski

  • 1Department of Cancer Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.

Molecular Cell
|June 15, 2010
PubMed

Insights

Rad5 protein facilitates DNA damage bypass by enabling sister chromatid recombination at stalled replication forks, ensuring genome stability and cell survival.

Area of Science:

  • Molecular Biology
  • Genetics
  • Cell Biology

Background:

  • DNA damage impedes replication, necessitating bypass mechanisms for cell viability and genome stability.
  • Rad5 (a PCNA polyubiquitin ligase and DNA-dependent ATPase) in yeast is crucial for error-free DNA damage bypass, but its mechanism remains unclear.
  • Rad5 is orthologous to human tumor suppressors, highlighting its importance in maintaining genomic integrity.

Purpose of the Study:

  • To elucidate the in vivo mechanism by which Rad5 facilitates DNA damage bypass.
  • To investigate the role of Rad5 in resolving stalled replication forks and completing chromosome duplication.
  • To analyze the specific DNA structures formed during damage bypass.

Main Methods:

  • Site-specific stalled replication forks were created at replication origins in yeast.
  • DNA structures formed during damage bypass were analyzed in vivo.
  • The function of Rad5's polyubiquitin ligase and ATPase domains in replication fork recombination was assessed.

Main Results:

  • Rad5 mediated the formation of recombination-dependent, X-shaped DNA structures containing Holliday junctions between sister chromatids.
  • Replication restart and chromosome duplication completion were impaired in mutants lacking these damage-induced chromatid junctions.
  • Both the polyubiquitin ligase and ATPase domains of Rad5 were essential for replication fork recombination.

Conclusions:

  • Rad5's multiple activities coordinate with homologous recombination factors to enable replication template switching at stalled forks.
  • These template switch events join sister chromatids, facilitating DNA damage bypass.
  • Rad5 plays a critical role in maintaining genome stability by resolving replication stress through recombination.

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