Complementation of aprataxin deficiency by base excision repair enzymes

Nucleic Acids Res. 2015 Feb 27;43(4):2271-81. doi: 10.1093/nar/gkv079. Epub 2015 Feb 6.


Abortive ligation during base excision repair (BER) leads to blocked repair intermediates containing a 5'-adenylated-deoxyribose phosphate (5'-AMP-dRP) group. Aprataxin (APTX) is able to remove the AMP group allowing repair to proceed. Earlier results had indicated that purified DNA polymerase β (pol β) removes the entire 5'-AMP-dRP group through its lyase activity and flap endonuclease 1 (FEN1) excises the 5'-AMP-dRP group along with one or two nucleotides. Here, using cell extracts from APTX-deficient cell lines, human Ataxia with Oculomotor Apraxia Type 1 (AOA1) and DT40 chicken B cell, we found that pol β and FEN1 enzymatic activities were prominent and strong enough to complement APTX deficiency. In addition, pol β, APTX and FEN1 coordinate with each other in processing of the 5'-adenylated dRP-containing BER intermediate. Finally, other DNA polymerases and a repair factor with dRP lyase activity (pol λ, pol ι, pol θ and Ku70) were found to remove the 5'-adenylated-dRP group from the BER intermediate. However, the activities of these enzymes were weak compared with those of pol β and FEN1.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adenosine Monophosphate / metabolism
  • Animals
  • Cell Extracts
  • Cell Line
  • Chickens
  • DNA Polymerase beta / genetics
  • DNA Polymerase beta / metabolism
  • DNA Repair
  • DNA Repair Enzymes / metabolism*
  • DNA-Binding Proteins / deficiency*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Flap Endonucleases / antagonists & inhibitors
  • Flap Endonucleases / immunology
  • Flap Endonucleases / metabolism
  • Gene Deletion
  • Humans
  • Mice
  • Nuclear Proteins / deficiency*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism


  • APTX protein, human
  • Cell Extracts
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Adenosine Monophosphate
  • DNA Polymerase beta
  • Flap Endonucleases
  • DNA Repair Enzymes