Understanding the role of Claspin in DNA damage checkpoints Public Deposited

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  • March 22, 2019
  • Sar, Funda
    • Affiliation: School of Medicine, Department of Biochemistry and Biophysics
  • DNA damage and replication checkpoints are signal transduction pathways that provide constant surveillance to maintain genome integrity. Checkpoints control a variety of cellular responses including DNA repair, chromatin remodeling and gene transcription. Claspin is an essential protein for the ATR-dependent activation of the DNA replication checkpoint response in Xenopus and human cells. The presence of stalled replication forks leads to phosphorylation of Claspin in both of the organisms and phosphorylated Claspin interacts with Chk1 and this interaction is essential for phosphorylation of Chk1 and checkpoint activation. Here we describe the purification and characterization of human Claspin. The protein has a ring-like structure and binds with high affinity to branched DNA molecules. These findings suggest that Claspin may be a component of the replication ensemble and plays a role in the replication checkpoint by directly associating with replication forks and with the various branched DNA structures likely to form at stalled replication forks due to DNA damage. In addition, we analyzed the importance of Claspin DNA binding for Chk1 activation by testing whether Claspin recruits Chk1 to DNA. These studies led to identification of Chk1 DNA binding activity. Chk1 possesses low DNA binding affinity to certain branched DNA structures and Claspin does not recruit Chk1 to DNA.
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  • Sancar, Aziz
Degree granting institution
  • University of North Carolina at Chapel Hill
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