Miscoding and misincorporation of 8-oxo-guanine during leading and lagging strand synthesis in Escherichia coli.
We examined whether strand identity with respect to DNA replication influences strand bias for 8-oxo-7,8-dihydroguanine (8-oxoG) mutagenesis. The specificity of 8-oxoG mutagenesis was determined in a mutM mutY or a mutT strain carrying the supF gene on one of two vectors that differed only in the orientation of supF with respect to a unique origin of replication. Most of the supF mutations in the mutM mutY strain were base substitutions (67%), predominantly G:C-->T:A transversions (> 64%), while the majority in the mutT strain were base substitutions (> 92%), predominantly A:T-->C:G transversions (> 91%). The distributions of frequently mutated sites of G:C-->T:A and A:T-->C:G transversions in the supF gene in the mutM mutY and mutT strains, respectively, did not differ markedly between the two vectors. These results suggest that gene orientation is not an important determinant of the strand bias of 8-oxoG mutagenesis.
Biological Institute, Graduate School of Science, Tohoku University, Sendai, Japan.
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T
Watanabe
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van Geldorp
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Najrana
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Yamamura
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Nunoshiba
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Yamamoto
D001483:Base Sequence; D045647:DNA Glycosylases; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D043382:DNA-Formamidopyrimidine Glycosylase; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D016368:Frameshift Mutation; D016153:Genes, Suppressor; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D017384:Sequence Deletion
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C096275:supF tRNA; C024829:8-hydroxyguanine; D006147:Guanine; D012343:RNA, Transfer; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli