title: Physical and functional interactions between Escherichia coli MutY glycosylase and mismatch repair protein MutS.
abstract: Escherichia coli MutY and MutS increase replication fidelity by removing adenines that were misincorporated opposite 7,8-dihydro-8-oxo-deoxyguanines (8-oxoG), G, or C. MutY DNA glycosylase removes adenines from these mismatches through a short-patch base excision repair pathway and thus prevents G:C-to-T:A and A:T-to-G:C mutations. MutS binds to the mismatches and initiates the long-patch mismatch repair on daughter DNA strands. We have previously reported that the human MutY homolog (hMYH) physically and functionally interacts with the human MutS homolog, hMutSalpha (Y. Gu et al., J. Biol. Chem. 277:11135-11142, 2002). Here, we show that a similar relationship between MutY and MutS exists in E. coli. The interaction of MutY and MutS involves the Fe-S domain of MutY and the ATPase domain of MutS. MutS, in eightfold molar excess over MutY, can enhance the binding activity of MutY with an A/8-oxoG mismatch by eightfold. The MutY expression level and activity in mutS mutant strains are sixfold and twofold greater, respectively, than those for the wild-type cells. The frequency of A:T-to-G:C mutations is reduced by two- to threefold in a mutS mutY mutant compared to a mutS mutant. Our results suggest that MutY base excision repair and mismatch repair defend against the mutagenic effect of 8-oxoG lesions in a cooperative manner.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, MD 21201, USA.
authors.forename: Haibo
authors.initials: H
authors.lastname: Bai
authors.forename: A-Lien
authors.initials: AL
authors.lastname: Lu
mesh_terms: D001665:Binding Sites; D045647:DNA Glycosylases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D006151:Guanosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D047468:Immunoprecipitation; D008957:Models, Genetic; D015394:Molecular Structure; D051719:MutS DNA Mismatch-Binding Protein / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029968:Escherichia coli Proteins; D006151:Guanosine; C046215:8-hydroxyguanosine; D045647:DNA Glycosylases; C061738:mutY adenine glycosylase; D051719:MutS DNA Mismatch-Binding Protein