The ataxia-oculomotor apraxia 1 gene product has a role distinct from ATM and interacts with the DNA strand break repair proteins XRCC1 and XRCC4

DNA Repair (Amst). 2004 Nov 2;3(11):1493-502. doi: 10.1016/j.dnarep.2004.06.017.


Ataxia-oculomotor apraxia 1 (AOA1) is an autosomal recessive neurodegenerative disease that is reminiscent of ataxia-telangiectasia (A-T). AOA1 is caused by mutations in the gene encoding aprataxin, a protein whose physiological function is currently unknown. We report here that, in contrast to A-T, AOA1 cell lines exhibit neither radioresistant DNA synthesis nor a reduced ability to phosphorylate downstream targets of ATM following DNA damage, suggesting that AOA1 lacks the cell cycle checkpoint defects that are characteristic of A-T. In addition, AOA1 primary fibroblasts exhibit only mild sensitivity to ionising radiation, hydrogen peroxide, and methyl methanesulphonate (MMS). Strikingly, however, aprataxin physically interacts in vitro and in vivo with the DNA strand break repair proteins XRCC1 and XRCC4. Aprataxin possesses a divergent forkhead associated (FHA) domain that closely resembles the FHA domain present in polynucleotide kinase, and appears to mediate the interactions with CK2-phosphorylated XRCC1 and XRCC4 through this domain. Aprataxin is therefore physically associated with both the DNA single-strand and double-strand break repair machinery, raising the possibility that AOA1 is a novel DNA damage response-defective disease.

Publication types

  • Comparative Study

MeSH terms

  • Apraxias / genetics*
  • Apraxias / metabolism*
  • Ataxia / genetics*
  • Ataxia / metabolism*
  • Ataxia Telangiectasia / genetics
  • Ataxia Telangiectasia / metabolism
  • Cell Line
  • DNA Damage
  • DNA Repair
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism*
  • Humans
  • In Vitro Techniques
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism*
  • Oculomotor Nerve Diseases / genetics
  • Oculomotor Nerve Diseases / metabolism
  • Radiation Tolerance
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Two-Hybrid System Techniques
  • X-ray Repair Cross Complementing Protein 1


  • APTX protein, human
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Recombinant Proteins
  • X-ray Repair Cross Complementing Protein 1
  • XRCC1 protein, human
  • XRCC4 protein, human