A new endonuclease from Escherichia coli acting at apurinic sites in DNA.
A new DNA endonuclease has been purified 3000-fold from Escherichia coli. The enzyme specifically catalyzes the formation of single strand breaks at apurinic and apyrimidinic sites in DNA, but has no activity on intact or single-stranded DNA. Further, the enzyme shows little or no activity on heavily ultraviolet-irradiated DNA, but cleaves x-irradiated DNA, presumably at apurinic and apyrimidinic sites introduced by the radiation treatment. The enzyme, which is tentatively named endonuclease IV, has no detectable associated exonuclease or DNA N-glycosidase activity and does not seem to be identical with any previously known E. coli endonuclease. Endonuclease IV has no Mg2+ requirement, and is fully active in the presence of EDTA. Enzyme activity is stimulated by 0.2 to 0.3 M NaCl and is unusually salt-resistant. Further, the enzyme is fairly heat-stable, and is not inhibited by tRNA. The sidimentation coefficient, S(o)20,w, is 3.4 S. It seems that endonuclease IV is active in DNA repair.
D001080:Apurinic Acid / Q000378:metabolism; D001435:Bacteriophages; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism*; D004270:DNA, Circular / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism* / Q000528:radiation effects; D003851:Deoxyribonucleases / Q000302:isolation & purification* / Q000378:metabolism; D004355:Drug Stability; D004720:Endonucleases / Q000302:isolation & purification* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D013329:Structure-Activity Relationship; D014466:Ultraviolet Rays; D014965:X-Rays
D004269:DNA, Bacterial; D004270:DNA, Circular; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D001080:Apurinic Acid; D003851:Deoxyribonucleases; D004720:Endonucleases