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Mec1ATR Autophosphorylation and Ddc2ATRIP Phosphorylation Regulates DNA Damage Checkpoint Signaling

Gonen Memisoglu1, Michael C Lanz2, Vinay V Eapen3

  • 1Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454, USA.

Cell Reports
|July 25, 2019
PubMed

Insights

Budding yeast adapt to DNA damage by autophosphorylation of Mec1 kinase at S1964, a process dependent on Ddc1 and Dpb11. Ddc2 protein levels and phosphorylation also regulate the DNA damage checkpoint response.

Area of Science:

  • Cellular biology
  • Molecular genetics
  • Biochemistry

Background:

  • Budding yeast activate the Mec1ATR-dependent DNA damage checkpoint upon encountering DNA double-strand breaks (DSBs).
  • Cells typically adapt and turn off checkpoint signaling after approximately 12 hours, even if the DSB persists.

Purpose of the Study:

  • To investigate the molecular mechanisms underlying checkpoint adaptation in budding yeast.
  • To elucidate the roles of Mec1 autophosphorylation and Ddc2 regulation in DNA damage response.

Main Methods:

  • Utilized budding yeast as a model organism.
  • Employed genetic mutations, specifically a non-phosphorylatable mec1-S1964A mutant.
  • Analyzed protein stability, phosphorylation, and localization using biochemical and imaging techniques.

Main Results:

  • Mec1 autophosphorylation at serine 1964 (S1964) is crucial for checkpoint adaptation; a mec1-S1964A mutant exhibits permanent cell cycle arrest.
  • Mec1 S1964 autophosphorylation is dependent on Ddc1Rad9 and Dpb11TopBP1 and correlates with adaptation timing.
  • The Mec1-binding partner Ddc2ATRIP is degraded upon DNA damage and its phosphorylation regulates the Mec1-Ddc2 complex localization to DNA lesions.

Conclusions:

  • Checkpoint adaptation involves Mec1 kinase autophosphorylation at S1964.
  • Changes in Ddc2 abundance and phosphorylation state are key regulators of the DNA damage checkpoint response and Mec1-Ddc2 complex localization.
Keywords:
DNA damage responseDdc2/ATRIPMec1/ATRPIKKRad53Rad9S. cerevisiaecell cyclecheckpoint

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