The excision of AP sites by the 3'-5' exonuclease activity of the Klenow fragment of Escherichia coli DNA polymerase I.
The 3' AP endonucleases (class I) are said to hydrolyze the phosphodiester bond 3' to AP sites yielding 3'-OH and 5'-phosphate ends; on the other hand, the resulting 3' terminal AP site is not removed by the 3'-5' exonuclease activity of the Klenow fragment [1]. We show that AP sites in DNA are easily removed by the 3'-5' exonuclease activity of the Klenow fragment and that they are excised as deoxyribose-5-phosphate. It is suggested that the 3' AP endonucleases are perhaps not the hydrolases they are supposed to be.
D004247:DNA / Q000378:metabolism; D004256:DNA Polymerase I / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D013379:Substrate Specificity
D029968:Escherichia coli Proteins; D010710:Phosphates; D010761:Phosphorus Radioisotopes; D004247:DNA; D004256:DNA Polymerase I; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase