The ataxia-telangiectasia related protein ATR mediates DNA-dependent phosphorylation of p53

Oncogene. 1999 Jul 8;18(27):3989-95. doi: 10.1038/sj.onc.1202973.


Levels of the tumour suppressor protein p53 are increased in response to a variety of DNA damaging agents. DNA damage-induced phosphorylation of p53 occurs at serine-15 in vivo. Phosphorylation of p53 at serine-15 leads to a stabilization of the polypeptide by inhibiting its interaction with Mdm2, a protein that targets p53 for ubiquitin-dependent degradation. However, the mechanisms by which DNA damage is signalled to p53 remain unclear. Here, we report the identification of a novel DNA-activated protein kinase that phosphorylates p53 on serine-15. Fractionation of HeLa nuclear extracts and biochemical analyses indicate that this kinase is distinct from the DNA-dependent protein kinase (DNA-PK) and corresponds to the human cell cycle checkpoint protein ATR. Immunoprecipitation studies of recombinant ATR reveal that catalytic activity of this polypeptide is required for DNA-stimulated phosphorylation of p53 on serine-15. These data suggest that ATR may function upstream of p53 in a signal transduction cascade initiated upon DNA damage and provide a biochemical assay system for ATR activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ataxia Telangiectasia / enzymology
  • Ataxia Telangiectasia / metabolism*
  • Ataxia Telangiectasia Mutated Proteins
  • Catalysis
  • Cell Cycle Proteins / physiology*
  • DNA / physiology
  • DNA-Activated Protein Kinase
  • DNA-Binding Proteins*
  • HeLa Cells
  • Humans
  • Nuclear Proteins
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism
  • Proteins / physiology*
  • Serine / metabolism
  • Tumor Suppressor Protein p53 / metabolism
  • Tumor Suppressor Proteins
  • p21-Activated Kinases


  • Cell Cycle Proteins
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Proteins
  • Tumor Suppressor Protein p53
  • Tumor Suppressor Proteins
  • Serine
  • DNA
  • Phosphatidylinositol 3-Kinases
  • ATM protein, human
  • ATR protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • DNA-Activated Protein Kinase
  • PAK1 protein, human
  • PRKDC protein, human
  • Protein-Serine-Threonine Kinases
  • p21-Activated Kinases