Frameshift mutagenesis by ultraviolet and γ radiations in Salmonella: SOS inducibility and effects of DNA polymerase I

In this paper, the authors report that UV- or γ-induced reversion of the frameshift hisC3076 marker, like that of the base-pair substitution leuA150 marker, is enhanced by the presence of the mucA,B+ plasmid pKM101 and by the introduction of a uvrB mutation to the test bacteria. Both types of mutagenesis by both agents are abolished by a recA mutation. Significantly different yields of frameshifts and base-pair substitutions were found following UV- or γ-irradiation of a polA mutant strain, suggesting that the enzyme DNA polymerase I plays an important role in one type of mutagenesis (frameshift) but not the other (base-pair substitution). (Auth.)