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Dephosphorylation of Orc2 by protein phosphatase 1 promotes the binding of the origin recognition complex to

Kyung Yong Lee1, June Sung Bae1, Sangwook Yoon1

  • 1Department of Biological Sciences, Seoul National University, Seoul 151-742, Republic of Korea.

Biochemical and Biophysical Research Communications
|May 6, 2014
PubMed

Insights

Protein phosphatase 1 (PP1) dephosphorylates Orc2, a subunit of the origin recognition complex (ORC). This dephosphorylation is crucial for ORC binding to chromatin and replication origins, ensuring cell cycle progression.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The origin recognition complex (ORC) is essential for DNA replication initiation.
  • Orc2 subunit phosphorylation by cyclin A/CDK2 during S phase causes ORC dissociation from chromatin.
  • Dephosphorylation by protein phosphatase 1 (PP1) is linked to ORC re-binding to chromatin.

Purpose of the Study:

  • To investigate the interaction between PP1 and Orc2.
  • To elucidate the role of PP1 in Orc2 dephosphorylation and chromatin binding.
  • To understand the cell cycle-dependent regulation of ORC binding.

Main Methods:

  • Co-immunoprecipitation to detect PP1-Orc2 interaction.
  • In vitro dephosphorylation assays.
  • Cell cycle analysis.
  • Chromatin binding assays.

Main Results:

  • PP1 directly interacts with Orc2.
  • PP1 binds to a specific motif (119-KSVSF-123) on Orc2.
  • PP1-mediated Orc2 dephosphorylation is cell cycle-dependent.
  • Orc2 dephosphorylation by PP1 is required for Orc2 chromatin binding.

Conclusions:

  • PP1 dephosphorylates Orc2 via a direct interaction.
  • This dephosphorylation event is critical for ORC's re-association with chromatin.
  • The PP1-Orc2 interaction facilitates the initiation of DNA replication for the next cell cycle.
Keywords:
Cell cycleDNA replicationDephosphorylationORCProtein phosphatase 1

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