Faculty Opinions recommendation of Two-stage mechanism for activation of the DNA replication checkpoint kinase Cds1 in fission yeast.

In fission yeast cells, Cds1 is the effector kinase of the DNA replication checkpoint. We previously showed that when the DNA replication checkpoint is activated, the repressor Yox1 is phosphorylated and inactivated by Cds1, resulting in activation of MluI-binding factor (MBF)–dependent transcription. This is essential to reinitiate DNA synthesis and for correct G1-to-S transition. Here we show that Cdc10, which is an essential part of the MBF core, is the target of the DNA damage checkpoint. When fission yeast cells are treated with DNA-damaging agents, Chk1 is activated and phosphorylates Cdc10 at its carboxy-terminal domain. This modification is responsible for the repression of MBF-dependent transcription through induced release of MBF from chromatin. This inactivation of MBF is important for survival of cells challenged with DNA-damaging agents. Thus Yox1 and Cdc10 couple normal cell cycle regulation in unperturbed conditions and the DNA replication and DNA damage checkpoints into a single transcriptional complex.

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Identification of three signaling molecules required for calcineurin-dependent monopolar growth induced by the DNA replication checkpoint in fission yeast

Biochemical and Biophysical Research Communications ◽

10.1016/j.bbrc.2017.07.129 ◽

2017 ◽

Vol 491 (4) ◽

pp. 883-889 ◽

Cited By ~ 1

Author(s):

Kazunori Kume ◽

Tomoyo Hashimoto ◽

Masashi Suzuki ◽

Masaki Mizunuma ◽

Takashi Toda ◽

...

Keyword(s):

Dna Replication ◽

Fission Yeast ◽

Signaling Molecules ◽

Replication Checkpoint ◽

Dna Replication Checkpoint

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Cleavage of Stalled Forks by Fission Yeast Mus81/Eme1 in Absence of DNA Replication Checkpoint

Molecular Biology of the Cell ◽

10.1091/mbc.e07-07-0728 ◽

2008 ◽

Vol 19 (2) ◽

pp. 445-456 ◽

Cited By ~ 62

Author(s):

Benoît Froget ◽

Joël Blaisonneau ◽

Sarah Lambert ◽

Giuseppe Baldacci

Keyword(s):

Dna Replication ◽

Fission Yeast ◽

Nuclease Activity ◽

S Phase ◽

Dna Breaks ◽

Replication Checkpoint ◽

Dna Structures ◽

Replication Arrest ◽

Dna Replication Checkpoint ◽

Stalled Fork

During replication arrest, the DNA replication checkpoint plays a crucial role in the stabilization of the replisome at stalled forks, thus preventing the collapse of active forks and the formation of aberrant DNA structures. How this checkpoint acts to preserve the integrity of replication structures at stalled fork is poorly understood. In Schizosaccharomyces pombe, the DNA replication checkpoint kinase Cds1 negatively regulates the structure-specific endonuclease Mus81/Eme1 to preserve genomic integrity when replication is perturbed. Here, we report that, in response to hydroxyurea (HU) treatment, the replication checkpoint prevents S-phase–specific DNA breakage resulting from Mus81 nuclease activity. However, loss of Mus81 regulation by Cds1 is not sufficient to produce HU-induced DNA breaks. Our results suggest that unscheduled cleavage of stalled forks by Mus81 is permitted when the replisome is not stabilized by the replication checkpoint. We also show that HU-induced DNA breaks are partially dependent on the Rqh1 helicase, the fission yeast homologue of BLM, but are independent of its helicase activity. This suggests that efficient cleavage of stalled forks by Mus81 requires Rqh1. Finally, we identified an interplay between Mus81 activity at stalled forks and the Chk1-dependent DNA damage checkpoint during S-phase when replication forks have collapsed.

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A tel2 Mutation That Destabilizes the Tel2-Tti1-Tti2 Complex Eliminates Rad3ATR Kinase Signaling in the DNA Replication Checkpoint and Leads to Telomere Shortening in Fission Yeast

Molecular and Cellular Biology ◽

10.1128/mcb.00175-19 ◽

2019 ◽

Vol 39 (20) ◽

Author(s):

Yong-jie Xu ◽

Saman Khan ◽

Adam C. Didier ◽

Michal Wozniak ◽

Yufeng Liu ◽

...

Keyword(s):

Dna Replication ◽

Fission Yeast ◽

Large Scale ◽

Gene Encoding ◽

Telomere Shortening ◽

Signaling Mechanism ◽

Replication Checkpoint ◽

Checkpoint Signaling ◽

Enhanced Sensitivity ◽

Dna Replication Checkpoint

ABSTRACT In response to perturbed DNA replication, ATR (ataxia telangiectasia and Rad3-related) kinase is activated to initiate the checkpoint signaling necessary for maintaining genome integrity and cell survival. To better understand the signaling mechanism, we carried out a large-scale genetic screen in fission yeast looking for mutants with enhanced sensitivity to hydroxyurea. From a collection of ∼370 primary mutants, we found a few mutants in which Rad3 (ATR ortholog)-mediated phospho-signaling was significantly compromised. One such mutant carried an uncharacterized mutation in tel2, a gene encoding an essential and highly conserved eukaryotic protein. Previous studies in various biological models have shown that Tel2 mainly functions in Tel2-Tti1-Tti2 (TTT) complex that regulates the steady-state levels of all phosphatidylinositol 3-kinase-like protein kinases, including ATR. We show here that although the levels of Rad3 and Rad3-mediated phospho-signaling in DNA damage checkpoint were moderately reduced in the tel2 mutant, the phospho-signaling in the DNA replication checkpoint was almost completely eliminated. In addition, the tel2 mutation caused telomere shortening. Since the interactions of Tel2 with Tti1 and Tti2 were significantly weakened by the mutation, destabilization of the TTT complex likely contributes to the observed checkpoint and telomere defects.

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