Properties of the nonlethal recombinational repair deficient mutants of bacteriophage T4

Abstract

The rate at which ³H thymidine is incorporated into DNA is increased in T4w-infected cells compared to wild-type when measured late in infection under conditions of low thymidine concentration. This increased DNA synthesis is sensitive to hydroxyurea but not to mitomycin C, and can be prevented by the addition of chloramphenicol early in infection. Also, DNA replicative intermediates isolated from T4w-infected cells late in infection sediment significantly faster than those isolated from wild-type-infected cells. In contrast, DNA replicative intermediates isolated from T4x-or T4y-infected cells sediment more slowly than those produced by wild-type T4. Cells coinfected with wild-type T4⁺ and T4x, y or w; or T4w and T4x or y, produce wild-type DNA replicative intermediates. Cells coinfected with T4x and T4y produce more slowly sedimenting DNA replicative intermediates. Cells coinfected with T4w and wild-type T4 show wild-type rates of DNA synthesis while cells coinfected with T4w and T4x or T4y show increased rates of DNA synthesis over that observed with wild-type alone.