O6-Methyl[8-3H]deoxyguanosine in a synthetic DNA polymer, poly(dC, dG, m6dG), is demethylated by cell-free extracts of EscherichiacoliB/r adapted by exposure to N-methyl-N′-nitro-N-nitrosoguanidine, as shown by the appearance of 3H-labeled deoxyguanosine in hydrolysates of the recovered DNA. The demethylating activity could not be detected in extracts of nonadapted E. coli. These results provide direct evidence that a previously described inducible repair activity in E. coli acts by demethylating O6-methylguanine at the DNA level.
ASJC Scopus subject areas
- Molecular Biology