Mismatch-specific thymine DNA glycosylase and DNA polymerase beta mediate the correction of G.T mispairs in nuclear extracts from human cells.
To avoid the mutagenic effect of spontaneous hydrolytic deamination of 5-methylcytosine, G.T mispairs, arising in DNA as a result of this process, should always be corrected to G.C pairs. We describe here the identification of a DNA glycosylase activity present in nuclear extracts from HeLa cells, which removes the mispaired thymine to generate an apyrimidinic (AP) site opposite the guanine. We further show, using a specific antibody and inhibitors, that the single nucleotide gap, created upon processing of the AP site, is filled in by DNA polymerase beta. This finding substantiates the proposed role of this enzyme in short-patch DNA repair.
Wiebauer
K
K
Friedrich Miescher Institute, Basel, Switzerland.
Jiricny
J
J
D016590:Aphidicolin; D001482:Base Composition; D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology*; D002855:Chromatography, Thin Layer; D004256:DNA Polymerase I / Q000378:metabolism*; D004260:DNA Repair; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004224:Diterpenes / Q000494:pharmacology; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D006147:Guanine; D006367:HeLa Cells / Q000201:enzymology; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D015183:Restriction Mapping; D013379:Substrate Specificity; D013941:Thymine
D004224:Diterpenes; D009838:Oligodeoxyribonucleotides; D016590:Aphidicolin; D006147:Guanine; D004256:DNA Polymerase I; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); D013941:Thymine