title: Escherichia coli mutY gene encodes an adenine glycosylase active on G-A mispairs.
abstract: Mutations in the mutY gene of Escherichia coli confer hypermutability reflecting G.C to T.A transversion mutations and result in a deficiency in methyl-independent G-A to G.C mismatch correction. In the present work, the mutY product has been purified to near homogeneity by virtue of its ability to restore G-A to G.C mismatch correction to cell-free extracts of a mutS mutY strain. The 36-kDa protein renders the strand containing the mispaired adenine labile to base-catalyzed cleavage and sensitive to cleavage by several apurinic/apyrimidinic-site endonucleases, with the sites of strand scission by both agents corresponding to the location of the mismatch. These findings indicate that MutY is a DNA glycosylase that hydrolyzes the glycosyl bond linking the mis-paired adenine to deoxyribose. MutY, a 5'-apurinic/apyrimidinic-site endonuclease, DNA polymerase I, and DNA ligase are sufficient to reconstitute MutY-dependent G-A to G.C repair in vitro.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, NC 27710.
authors.forename: K G
authors.initials: KG
authors.lastname: Au
authors.forename: S
authors.initials: S
authors.lastname: Clark
authors.forename: J H
authors.initials: JH
authors.lastname: Miller
authors.forename: P
authors.initials: P
authors.lastname: Modrich
mesh_terms: D000225:Adenine; D001482:Base Composition; D045647:DNA Glycosylases; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D006147:Guanine; D009699:N-Glycosyl Hydrolases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D006147:Guanine; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D000225:Adenine