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Examination of Mitotic and Meiotic Fission Yeast Nuclear Dynamics by Fluorescence Live-cell Microscopy
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The phosphorylation network for efficient activation of the DNA replication checkpoint in fission yeast

Ming Yue1, Amanpreet Singh, Zhuo Wang

  • 1Department of Biochemistry and Molecular Biology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio 45435, USA.

The Journal of Biological Chemistry
|May 13, 2011
PubMed

Insights

Efficient activation of the Cds1 effector kinase requires five specific phosphorylations. These phosphorylation events, involving Rad3, Mrc1, and Rad9, cooperate to fully activate the DNA replication checkpoint pathway.

Area of Science:

  • Cellular biology
  • Molecular genetics
  • Biochemistry

Background:

  • Protein phosphorylation is crucial for activating cellular checkpoints.
  • Genome-wide studies have identified numerous checkpoint kinase targets.
  • A comprehensive understanding of checkpoint activation phosphorylation networks is lacking.

Purpose of the Study:

  • To elucidate the complete phosphorylation network required for DNA replication checkpoint activation in Schizosaccharomyces pombe.
  • To identify the specific phosphorylation events and their cooperative mechanisms essential for effector kinase Cds1 activation.

Main Methods:

  • Investigated protein phosphorylation using biochemical assays.
  • Utilized genetic approaches in Schizosaccharomyces pombe to study checkpoint activation.
  • Analyzed the roles of Rad3, Cds1, Mrc1, and Rad9 in the DNA replication checkpoint pathway.

Main Results:

  • Identified five key phosphorylations essential for efficient Cds1 activation during DNA replication arrest.
  • Demonstrated that three parallel Rad3-dependent phosphorylations on Mrc1 and Rad9 are required for efficient Thr(11) phosphorylation of Cds1.
  • Showed that Mrc1 phosphorylation by Rad3 does not depend on Rad9 phosphorylation, suggesting distinct activation mechanisms for Rad3.

Conclusions:

  • The activation of the DNA replication checkpoint in fission yeast involves a complex, cooperative phosphorylation network.
  • Efficient Cds1 activation relies on a coordinated sequence or parallel action of multiple phosphorylation events.
  • The findings provide new insights into the regulatory mechanisms of DNA replication checkpoints and sensor kinase activation.

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