Induction of frameshift mutations by caffeine in Escherichia coli K12

Caffeine induced reversions of five different frameshift mutations in Escherichia coli K12. Only those mutations which were very sensitive to reversion-induction by 9-amino-acridine (9AA) were also sensitive to caffeine. Caffeine mutagenesis was not due to inhibition of cellular repair functions, but to the production of replication errors, which were corrected very efficiently by mismatch repair. From the results reported here we conclude that the targets for caffeine mutagenesis are long runs of GC base pairs, and that this mutagen induces -1 frameshifts.