Normal processing of AP sites in Apn1-deficient Saccharomyces cerevisiae is restored by Escherichia coli genes expressing either exonuclease III or endonuclease III

Molecular Microbiology
J Y Masson, D Ramotar

Abstract

Escherichia coli exonuclease III and endonuclease III are two distinct DNA-repair enzymes that can cleave apurinic/apyrimidinic (AP) sites by different mechanisms. While the AP endonuclease activity of exonuclease III generates a 3'-hydroxyl group at AP sites, the AP lyase activity of endonuclease III produces a 3'-alpha,beta unsaturated aldehyde that prevents DNA-repair synthesis. Saccharomyces cerevisiae Apn1 is the major AP endonuclease/3'-diesterase that also produces a 3'-hydroxyl group at the AP site, but it is unrelated to either exonuclease III or endonuclease III. apn1 deletion mutants are unable to repair AP sites generated by the alkylating agent methyl methane sulphonate and display a spontaneous mutator phenotype. This work shows that either exonuclease III or endonuclease III can functionally replace yeast Apn1 in the repair of AP sites. Two conclusions can be derived from these findings. The first of these conclusions is that yeast cells can complete the repair of AP sites even though they are cleaved by AP lyase. This implies that AP lyase can contribute significantly to the repair of AP sites and that yeast cells have the ability to process the alpha,beta unsaturated aldehyde produced by endonuclease III. The s...Continue Reading

Citations

Aug 1, 1998·Mutation Research·B J GlassnerL D Samson
Apr 12, 2000·European Journal of Biochemistry·G Frosina
Oct 2, 2013·Current Genetics·Mustapha AouidaMagdy M Mahfouz
Jul 30, 2010·Mutation Research·James M DaleyDindial Ramotar
Jul 24, 2012·DNA Repair·Xiaoming YangDindial Ramotar
Dec 29, 2009·DNA Repair·Chadi ZakariaDindial Ramotar
Nov 2, 2006·Environmental and Molecular Mutagenesis·Kaouther TounektiDindial Ramotar
Jan 1, 1997·Biochemistry and Cell Biology = Biochimie Et Biologie Cellulaire·D Ramotar

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