Mutants of E. coli in which bacteriophage P4 cannot activate the late genes of its helper, bacteriophage P2

Abstract

Mutants of Escherichia coli strain C have been isolated which fail to support normal growth of satellite phage P4 even though its helper P2 is present as a prophage. The host mutations prevent P4-directed activation of the late genes of the P2 helper. In contrast, activation of P2 late genes during P2 infection is unimpaired. These results indicate that P2 and P4 activate the late genes of P2 by different mechanisms. P4-directed transactivation is temperature-sensitive in two of the four mutants. Mutants of P4 which overcome the defect in the host can be isolated only on these thermosensitive host mutants. Growth of coliphages λ, φ80, P1, T4, and φX174 is defective on one or more of these bacterial mutants. Growth of T7 is not affected.