title: The mechanisms of action of E. coli endonuclease III and T4 UV endonuclease (endonuclease V) at AP sites.
abstract: Treatment of DNA containing AP sites with either T4 UV endonuclease or with E. coli endonuclease III followed by a human class II AP endonuclease releases a putative beta-elimination product. This result suggests that both the T4 endonuclease and E. coli endonuclease III class I AP endonucleases catalyze phosphodiester bond cleavage via a lyase- rather than a hydrolase mechanism. Indeed, we have not detected a class I AP endonuclease which hydrolytically catalyzes phosphodiester bond cleavage. Whereas these enzymes use a lyase-like rather than a hydrolytic mechanism, they nonetheless catalyze phosphodiester bond cleavage. We suggest that the term endonuclease can be properly applied to them.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004279:DNA, Viral / Q000378:metabolism*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043224:Deoxyribonuclease (Pyrimidine Dimer); D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D013604:T-Phages / Q000201:enzymology*; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004279:DNA, Viral; D029968:Escherichia coli Proteins; D014764:Viral Proteins; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; C470698:endonuclease V, phage T4; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase