Base excision repair synthesis of DNA containing 8-oxoguanine in Escherichia coli

다국어 초록 (Multilingual Abstract)

8-oxo-7,8-dihydroguanine (8-oxo-G) in DNA is a mutagenic adduct formed by reactive oxygen species. In Escherichia coli, 2,6-dihydroxy-5N-for-mamidopyrimidine (Fapy)-DNA glycosylase (Fpg) re-moves this mutagenic adduct from DNA. In this report, we demonstrate base excision repair (BER) synthesis of DNA containing 8-oxo-G with Fpg in vitro. Fpg cut the oligonucleotide at the site of 5 phosphate termini. Next, 3 phosphatase(s) in the supernatant obtained by precipitating a crude extract of E. coli with 40% ammonium sulfate, removed the 3 phosphate group at the gap, thus exposing the 3 hydroxyl group to prime DNA syn-thesis. DNA polymerase and DNA ligase then com-pleted the repair. These results indicate the biolo-gical significance of the glycosylase and apurinic/ apyrimidinic (AP) lyase activities of Fpg, in concert with 3 phosphatase(s) to create an appropriately gapped substrate for eficient BER synthesis of