Abstract
An improved system to examine forward mutations that occurred in the supF gene of Escherichai coli carried on a multicopy plasmid is described. The system was validated by measuring spontaneous mutations of supF plasmids propagated in wild-type, recA- and mutM- mutY- E. coli strains, the mutation frequencies of which were 1.3 × 10-7, 6.3 × 10-7 and 1.5 × 10-6, respectively. Sequence analysis of the supF mutant plasmids revealed that G:C→T:A and G:C→C:G transversions dominated. This improved system allows rapid scoring and sequencing forward mutations in the supF gene, thus permitting its use as a genetic target for repair and mutagenesis studies in bacteria and mammalian cells.
