Related Experiment Video

Updated: Jun 12, 2025

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
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Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

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CDK-dependent phosphorylation regulates PNKP function in DNA replication

Fatemeh Mashayekhi1, Elham Zeinali1, Cassandra Ganje1

  • 1Department of Oncology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada.

The Journal of Biological Chemistry
|October 12, 2024
PubMed

Insights

Polynucleotide kinase-phosphatase (PNKP) is vital for DNA replication and Okazaki fragment maturation, preventing DNA breaks linked to cancer and neurodegenerative diseases.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Okazaki fragment maturation (OFM) is essential for DNA replication and genome stability.
  • Dysregulation of OFM causes DNA single-strand breaks, contributing to diseases like cancer.
  • Alternative OFM pathways, including LIG3-XRCC1, are being discovered alongside the canonical FEN1-LIG1 pathway.

Purpose of the Study:

  • To investigate the role of polynucleotide kinase-phosphatase (PNKP) in DNA replication and Okazaki fragment maturation.
  • To elucidate the mechanism and regulation of PNKP in DNA replication fork dynamics.

Main Methods:

  • Functional experiments to assess PNKP's role at replication forks.
  • Co-immunoprecipitation to determine PNKP's association with PCNA.
  • Cellular depletion studies to observe replication defects.
  • In vitro kinase assays and site-directed mutagenesis to analyze PNKP phosphorylation by CDK1/2.

Main Results:

  • PNKP is enriched at DNA replication forks and interacts with PCNA.
  • PNKP depletion causes defects similar to other OFM-related proteins.
  • PNKP is phosphorylated by CDK1/2 at multiple sites, crucial for DNA replication.
  • PNKP facilitates Okazaki fragment joining.

Conclusions:

  • PNKP plays a novel and significant role in Okazaki fragment maturation.
  • PNKP's function is regulated by CDK-mediated phosphorylation.
  • PNKP contributes to maintaining genome stability through its involvement in DNA replication.
Keywords:
CDKsDNA replicationFEN1Okazaki fragmentsPNKPgenome instability

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