Aprataxin, causative gene product for EAOH/AOA1, repairs DNA single-strand breaks with damaged 3'-phosphate and 3'-phosphoglycolate ends

Nucleic Acids Res. 2007;35(11):3797-809. doi: 10.1093/nar/gkm158. Epub 2007 May 22.


Aprataxin is the causative gene product for early-onset ataxia with ocular motor apraxia and hypoalbuminemia/ataxia with oculomotor apraxia type 1 (EAOH/AOA1), the clinical symptoms of which are predominantly neurological. Although aprataxin has been suggested to be related to DNA single-strand break repair (SSBR), the physiological function of aprataxin remains to be elucidated. DNA single-strand breaks (SSBs) continually produced by endogenous reactive oxygen species or exogenous genotoxic agents, typically possess damaged 3'-ends including 3'-phosphate, 3'-phosphoglycolate, or 3'-alpha, beta-unsaturated aldehyde ends. These damaged 3'-ends should be restored to 3'-hydroxyl ends for subsequent repair processes. Here we demonstrate by in vitro assay that recombinant human aprataxin specifically removes 3'-phosphoglycolate and 3'-phosphate ends at DNA 3'-ends, but not 3'-alpha, beta-unsaturated aldehyde ends, and can act with DNA polymerase beta and DNA ligase III to repair SSBs with these damaged 3'-ends. Furthermore, disease-associated mutant forms of aprataxin lack this removal activity. The findings indicate that aprataxin has an important role in SSBR, that is, it removes blocking molecules from 3'-ends, and that the accumulation of unrepaired SSBs with damaged 3'-ends underlies the pathogenesis of EAOH/AOA1. The findings will provide new insight into the mechanism underlying degeneration and DNA repair in neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Monophosphate / metabolism
  • Apraxias / genetics*
  • Ataxia / genetics*
  • DNA / chemistry
  • DNA / metabolism
  • DNA Breaks, Single-Stranded*
  • DNA Ligase ATP
  • DNA Ligases / metabolism
  • DNA Polymerase beta / metabolism
  • DNA Repair*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / physiology*
  • Glycolates / metabolism
  • Guanosine Monophosphate / metabolism
  • Humans
  • Mutation
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / physiology*
  • Phosphates / metabolism
  • Phosphoric Monoester Hydrolases / metabolism
  • Poly-ADP-Ribose Binding Proteins
  • Protein Structure, Tertiary
  • Substrate Specificity
  • Xenopus Proteins


  • APTX protein, human
  • DNA-Binding Proteins
  • Glycolates
  • Nuclear Proteins
  • Phosphates
  • Poly-ADP-Ribose Binding Proteins
  • Xenopus Proteins
  • Adenosine Monophosphate
  • Guanosine Monophosphate
  • DNA
  • DNA Polymerase beta
  • Phosphoric Monoester Hydrolases
  • DNA Ligases
  • DNA Ligase ATP
  • DNA ligase III alpha protein, Xenopus
  • LIG3 protein, human
  • phosphoglycolate