title: Endonucleases in yeast mitochondria: apurinic and manganese-stimulated deoxyribonuclease activities in the inner mitochondrial membrane of Saccharomyces cerevisiae.
abstract: An apurinic endonuclease activity has been characterized in yeast mitochondrial. It is dependent on Mg2+, stimulated by about 50% in the presence of 50 mM NaCl and inhibited at higher NaCl concentrations. It is located in the inner mitochondrial membrane and requires high concentrations of detergent (1.5-3% Triton X-100) to be extracted. The same treatment extracts several other endonuclease activities: the two Mg2+-dependent endonuclease activities cleaving double-stranded DNA at pH 7.5 and 5.4 respectively, the ethidium-bromide-stimulated endonuclease activity, the endonuclease activity cleaving single-stranded DNA at pH 7.l5 [Jacquemin-Sablon et al. (1979) Biochemistry, 18, 119-127], and a manganese-stimulated deoxyribonuclease activity cleaving double-stranded DNA at pH 7.5 which has been discovered during the present work. Another endonuclease activity cleaving double-stranded DNA at pH 7.5 in the presence of Mg2+, slightly stimulated by low NaCl concentrations and inhibited by ethidium bromide is extracted from the membrane pellet remaining after the treatment with 1.5% Triton X-100 by a second treatment with 1.5% Triton X-100 plus 1 M KCl. The presence in the mitochondrial membrane of this apurinic endonuclease activity indicates that, like nuclear and prokaryotic DNA, yeast mitochondrial DNA is also subject to specialized repair systems.
mesh_terms: D002413:Cations, Divalent; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D003851:Deoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008928:Mitochondria / Q000201:enzymology*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
chemical_list: D002413:Cations, Divalent; D008345:Manganese; D003851:Deoxyribonucleases; D004720:Endonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase