8-Hydroxyguanine, an abundant form of oxidative DNA damage, causes G----T and A----C substitutions.

摘要: Mutations caused by oxidative DNA damage may contribute to human disease. A major product of that is 8-hydroxyguanine (oh8Gua). Because differences in experimental design, the base pairing specificity oh8G vivo not completely resolved. Here, oh8dGTP and polymerase were used two complementary bacteriophage plaque color assays examine mutagenic oh8Gua vivo. The first a reversion assay detects all three single-base substitutions misreading guanine analogues inserted at specific site. site gave mutation frequency 0.7%. Twenty-two 23 mutations G→T substitutions. second assay, forward tests mispairing potential any altered nucleotide 1) during incorporation as substrate nucleotide, 2) after multiple incorporations into single-stranded gap region M13mp2. Substituting for dGTP polymerization produced 16% mutants; classes observed, both with A. Seventy-six 78 A→C substitutions, These thus illustrate replication template causing misincorporation oh8Gua.A mispairs.