F-Factor-mediated restriction of bacteriophage T7: synthesis of RNA and protein in T7-infected Escherichia coli F- and F+ cells

Abstract

Bacteriophage T7 is unable to productively infect Escherichia coli strains carrying the sex factor F. T7 phage development, in terms of RNA and protein synthesis, was compared in T7-infected isogenic F- and F+ strains of E. coli. Slightly less T7 early mRNA and early protein were synthesized in F+ cells. In addition to the defect in T7 late protein production in F+ cells reported by others, significantly less T7 late mRNA was synthesized, about one-half of that produced in T7-infected F- cells. Moreover, host RNA synthesis was not completely inhibited. The protein-synthesizing ability of T7-infected F+ cells decayed much faster than that of F- cells both in vivo and in vitro. This faster decay appears to explain the failure of F+ cells to produce T7 late protein in vivo, even in the presence of a considerable amount of translatable T7 late mRNA. Therefore, it may not be necessary to postulate the involvement of specific translational discrimination against T7 late mRNA, although it appears that F-factor-mediated restriction of T7 involves changes in transcription as well as translation.