Biochemical Studies on the χ Mutation of Bacteriophage T4: Differential Inhibition of χ ⁺ and χ DNA Synthesis by Mitomycin C

Abstract

Biochemical studies were carried out to determine the effect of chi mutation on T4 DNA synthesis. The rate and final extent of DNA synthesis are almost the same with T4D- and T4chi-infected cells, although the burst size of T4chi is about one-sixth that of the wild type. The DNA synthesis of T4chi-infected cells is more readily inhibited by mitomycin C than is that of T4 wild type. When mitomycin C was added during active phage growth, DNA synthesis of T4chi halted almost immediately. T4 DNA polymerases isolated from chi(+)- and chi-infected cells, however, exhibit no difference with regard to their sensitivities to mitomycin C, priming activities with alkylated or ultraviolet light-irradiated templates and other enzymatic properties.