title: AP endonuclease and uracil DNA glycosylase activities in Deinococcus radiodurans.
abstract: An endonuclease specific for apurinic/apyrimidinic (AP) sites was identified and purified from extracts of Deinococcus radiodurans. The enzyme is 34.5 kD, has no activity towards normal, alkylated, uracil-containing, or UV-irradiated DNA, and is active in the presence of EDTA. The addition of up to 10 mM Mg2+ or Mn2+ did not affect activity, but higher concentrations were inhibitory. There is no associated exonuclease activity, either in the presence or absence of divalent cation. Optimal reaction conditions were 150 mM NaCl and pH 7.5. A uracil DNA glycosylase was also detected, active in the presence of EDTA, selectively removing uracil from DNA without generating other byproducts. The optimal reaction conditions were 50 mM NaCl and pH 7.5. Implications for base excision repair in D. radiodurans are discussed.
authors.affiliation: Department of Pathology, F.E. Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4799.
authors.forename: C I
authors.initials: CI
authors.lastname: Masters
authors.forename: B E
authors.initials: BE
authors.lastname: Moseley
authors.forename: K W
authors.initials: KW
authors.lastname: Minton
mesh_terms: D004249:DNA Damage; D045647:DNA Glycosylases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry* / Q000528:radiation effects; D004270:DNA, Circular / Q000737:chemistry / Q000528:radiation effects; D004278:DNA, Superhelical / Q000737:chemistry / Q000528:radiation effects; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000302:isolation & purification; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006094:Gram-Positive Bacteria / Q000201:enzymology / Q000235:genetics*; D009699:N-Glycosyl Hydrolases / Q000235:genetics*; D014170:Transformation, Genetic; D014466:Ultraviolet Rays; D051981:Uracil-DNA Glycosidase
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular; D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D051981:Uracil-DNA Glycosidase; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase