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Non-catalytic function for ATR in the checkpoint response

Troy D McSherry1, Ana A Kitazono, Ali Javaheri

  • 1Center for Molecular Oncology, University of Chicago, Chicago, Illinois, USA.

Cell Cycle (Georgetown, Tex.)
|August 28, 2007
PubMed

Insights

The non-catalytic portion of ATR kinases is crucial for DNA damage response. This conserved function involves the spindle assembly checkpoint, linking ATR to Mad1 and Mad2, independent of its catalytic activity.

Area of Science:

  • Cell Biology
  • Genetics
  • Molecular Biology

Background:

  • The ATR (Ataxia Telangiectasia and Rad3-related) kinase family is vital for eukaryotic DNA damage response.
  • ATR kinases orchestrate cell cycle arrest, DNA repair, and apoptosis following genomic insults.
  • The catalytic domain is a small part of these large kinases, suggesting non-catalytic regions have functions.

Purpose of the Study:

  • To investigate the conserved function of the non-catalytic portion of ATR kinases.
  • To determine the role of Xenopus ATR (XATR) in Saccharomyces cerevisiae mec1 mutants.
  • To elucidate the specific checkpoint pathways involved in ATR's function.

Main Methods:

  • Expression of wild-type and kinase-defective XATR in S. cerevisiae mec1 mutants.
  • Analysis of checkpoint defects, cell cycle arrest, and dependence on specific yeast factors (Ddc2, Rad9, Rad53, Mad1, Mad2).
  • Creation and analysis of a yeast strain with a truncated mec1 lacking the kinase domain.

Main Results:

  • Xenopus ATR (XATR) suppressed the mec1 mutant checkpoint defect, inducing DNA damage-dependent mitotic arrest.
  • Suppression required yeast Ddc2 and Rad9 but was independent of Rad9 modification and Rad53 activation.
  • XATR-mediated suppression involved spindle checkpoint factors Mad1 and Mad2, suggesting a role in the spindle assembly checkpoint.
  • A truncated mec1 mutant was partially checkpoint proficient and induced Mad2-dependent mitotic arrest.

Conclusions:

  • The non-catalytic portion of ATR kinases has a conserved function in checkpoint control.
  • ATR kinases are linked to the spindle assembly checkpoint pathway via their non-catalytic regions.
  • This connection between ATR and the spindle checkpoint is conserved across species.

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