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Topoisomerase II inactivation prevents the completion of DNA replication in budding yeast

Jonathan Baxter1, John F X Diffley

  • 1Cancer Research UK London Research Institute, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.

Molecular Cell
|June 24, 2008
PubMed

Insights

Depleting type II topoisomerase (Top2) causes DNA damage during mitosis, while inactivating it leads to a G2 arrest. These distinct mechanisms highlight differences in how Top2 loss impacts cell survival and DNA replication.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Type II topoisomerases (Top2) are crucial for decatenating double-stranded DNA.
  • Top2 inhibitors are vital in cancer chemotherapy and antibiotic treatments.
  • Mechanisms of cell death from Top2 depletion versus inactivation remain unclear.

Purpose of the Study:

  • To compare the distinct mechanisms of cell killing caused by Top2 depletion and catalytic inactivation.
  • To elucidate the cellular consequences of impaired DNA decatenation and replication.
  • To investigate the role of DNA damage checkpoints in response to Top2 dysfunction.

Main Methods:

  • Utilized budding yeast as a model organism.
  • Employing Top2 protein depletion and expression of catalytically inactive Top2 mutants.
  • Analyzing DNA decatenation, chromosome segregation, DNA replication, and cell cycle progression.
  • Investigating DNA damage checkpoint activation.

Main Results:

  • Top2 depletion prevented DNA decatenation, leading to chromosome missegregation and lethal DNA damage during cytokinesis.
  • Catalytically inactive Top2 induced a stable G2 arrest dependent on an intact DNA damage checkpoint.
  • Inactive Top2 expression resulted in failed DNA replication and daughter DNA molecules with catenations and gaps.

Conclusions:

  • Top2 depletion and inactivation trigger divergent cell-lethal pathways.
  • Findings offer insights into the DNA replication termination, catenation checkpoint, and anti-Top2 drug mechanisms.
  • This research informs the design of novel anti-Top2 therapeutic strategies.

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