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PCNA functions as a molecular platform to trigger Cdt1 destruction and prevent re-replication

Emily E Arias1, Johannes C Walter

  • 1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.

Nature Cell Biology
|December 20, 2005
PubMed

Insights

Proliferating cell nuclear antigen (PCNA) binding triggers the destruction of Cdt1, a key protein that limits DNA replication. This ensures cells replicate their DNA only once per cell cycle.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Ubiquitin-mediated proteolysis of Cdt1 (Cdc10-dependent transcript 1) is crucial for limiting DNA replication to once per cell cycle in metazoans.
  • Cdt1 destruction on chromatin during DNA replication is a key regulatory mechanism.

Purpose of the Study:

  • To investigate the mechanism of replication-dependent Cdt1 proteolysis.
  • To identify factors involved in Cdt1 destruction during DNA replication.

Main Methods:

  • Utilized Xenopus egg extracts to study Cdt1 proteolysis.
  • Investigated the interaction between Cdt1 and proliferating cell nuclear antigen (PCNA).
  • Mutated the PCNA-interaction motif in Cdt1 and assessed its stability and function.

Main Results:

  • Replication-dependent Cdt1 proteolysis requires its interaction with PCNA.
  • A conserved PCNA-interaction motif in Cdt1 is essential for its destruction.
  • Mutation of the PCNA-interaction motif leads to Cdt1 stabilization and DNA re-replication.
  • DDB1, a component of the Cul4 E3 ubiquitin ligase, is also required for Cdt1 destruction.
  • PCNA binding facilitates DDB1 chromatin loading, activating the Cdt1-Cul4(DDB1) ligase complex.

Conclusions:

  • PCNA acts as a platform for Cdt1 destruction during DNA replication.
  • This mechanism ensures efficient and timely inactivation of Cdt1, preventing re-replication.
  • PCNA-mediated Cdt1 degradation is vital for maintaining genomic stability.

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