The C-terminal domain of MutY glycosylase determines the 7,8-dihydro-8-oxo-guanine specificity and is crucial for mutation avoidance.
Escherichia coli MutY is an adenine DNA glycosylase active on DNA substrates containing A/G, A/8-oxoG, or A/C mismatches and also has a weak guanine glycosylase activity on G/8-oxoG-containing DNA. The N-terminal domain of MutY, residues 1-226, has been shown to retain catalytic activity. Substrate binding, glycosylase, and Schiff base intermediate formation activities of the truncated and intact MutY were compared. MutY has high binding affinity with 8-oxoG when mispaired with A, G, T, C, or inosine. The truncated protein has more than 18-fold lower affinities for binding various 8-oxoG-containing mismatches when compared with intact MutY. MutY catalytic activity toward A/8-oxoG-containing DNA is much faster than that on A/G-containing DNA whereas deletion of the C-terminal domain reduces its catalytic preference for A/8-oxoG-DNA over A/G-DNA. MutY exerts more inhibition on the catalytic activity of MutM (Fpg) protein than does truncated MutY. The tight binding of MutY with GO mispaired with T, G, and apurinic/apyrimidinic sites may be involved in the regulation of MutM activity. An E. coli mutY strain that produces an N-terminal 249-residue truncated MutY confers a mutator phenotype. These findings strongly suggest that the C-terminal domain of MutY determines the 8-oxoG specificity and is crucial for mutation avoidance by oxidative damage.
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Department of Biochemistry and Molecular Biology, University of Maryland at Baltimore, Baltimore, Maryland 21201, USA.
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D045647:DNA Glycosylases; D004260:DNA Repair; D043382:DNA-Formamidopyrimidine Glycosylase; D029968:Escherichia coli Proteins; D006151:Guanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D008957:Models, Genetic; D016296:Mutagenesis; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D013379:Substrate Specificity
D029968:Escherichia coli Proteins; D006151:Guanosine; C046215:8-hydroxyguanosine; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli