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DNA damage induces Cdt1 proteolysis in fission yeast through a pathway dependent on Cdt2 and Ddb1

Emma Ralph1, Erik Boye, Stephen E Kearsey

  • 1Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.

EMBO Reports
|October 14, 2006
PubMed

Insights

DNA damage triggers Cdt1 protein degradation in fission yeast, independent of major checkpoints. This conserved process involves Cdt2 and Ddb1, crucial for regulating Cdt1 levels and maintaining genome stability.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Cdt1 protein is essential for initiating DNA replication by licensing replication origins.
  • Understanding cell cycle regulation and DNA damage response pathways is crucial for genome stability.

Purpose of the Study:

  • To investigate the regulation of Cdt1 protein levels during DNA damage and cell cycle progression in Schizosaccharomyces pombe.
  • To elucidate the molecular mechanisms and protein factors involved in Cdt1 degradation.

Main Methods:

  • Proteolysis assays in Schizosaccharomyces pombe.
  • Genetic analysis involving mutations in DNA damage and checkpoint genes (Rad3, Cds1).
  • Investigation of the roles of Cdt2 and Ddb1 in Cdt1 regulation using ubiquitin ligase components.

Main Results:

  • Cdt1 undergoes proteolysis in M and G1 phases upon DNA damage in fission yeast.
  • This degradation is independent of Rad3 and Cds1, indicating a novel DNA damage response pathway.
  • Damage-induced Cdt1 degradation requires Cdt2 and Ddb1, components of the Cul4 ubiquitin ligase complex.
  • Cdt2 and Ddb1 also regulate Cdt1 levels during normal cell cycle progression.

Conclusions:

  • A conserved mechanism exists from yeast to Metazoa for Cdt1 degradation in response to DNA damage.
  • The Cul4 ubiquitin ligase complex, via Cdt2 and Ddb1, plays a key role in controlling Cdt1 levels.
  • Downregulation of Cdt1 may contribute to genome stability by modulating dNTP pools during DNA repair.

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