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Tipin-replication protein A interaction mediates Chk1 phosphorylation by ATR in response to genotoxic stress

Michael G Kemp1, Zafer Akan, Seçil Yilmaz

  • 1Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.

The Journal of Biological Chemistry
|March 18, 2010
PubMed

Insights

The Timeless-Tipin complex, interacting with Replication Protein A (RPA), is crucial for activating the ATR-Chk1 DNA damage pathway. This interaction ensures proper cell response to DNA damage and replication stress.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Mammalian Timeless is a key protein involved in DNA repair and cell cycle checkpoints.
  • Timeless functions in a complex with Tipin (Timeless-interacting protein).
  • The ATR-Chk1 pathway is critical for responding to DNA damage and replication stress.

Purpose of the Study:

  • To elucidate the mechanism by which the Timeless-Tipin complex mediates the ATR-Chk1 DNA damage checkpoint pathway.
  • To understand the role of the Tipin-Replication Protein A (RPA) interaction in this process.

Main Methods:

  • Investigated the Timeless-Tipin complex's function in the ATR-Chk1 pathway.
  • Examined the interaction between Tipin and the 34-kDa subunit of RPA.
  • Assessed the stabilization of protein complexes on RPA-coated single-stranded DNA (ssDNA).

Main Results:

  • The Timeless-Tipin complex specifically mediates Chk1 phosphorylation by ATR in response to DNA damage and replication stress.
  • Tipin interacts with the 34-kDa subunit of RPA, stabilizing Timeless-Tipin and Tipin-Claspin complexes on RPA-coated ssDNA.
  • This stabilization promotes Claspin-mediated phosphorylation of Chk1 by ATR.

Conclusions:

  • RPA-coated ssDNA is essential for ATR recruitment and activation.
  • The Timeless-Tipin complex, via Tipin and Claspin, plays a vital role in ATR's action on Chk1.
  • This mechanism highlights a novel regulatory role for RPA in the DNA damage response pathway.

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