FUNCTION OF BACTERIOPHAGE-T4 INTERNAL PROTEIN-I IN A RESTRICTIVE STRAIN OF ESCHERICHIA-COLI

Bacteriophage T4 internal protein I (IPI) mutants are restricted by a strain of Escherichia coli, called CT596. These mutants appear to adsorb to this host and inject their DNA with the same efficiency as wild-type phages. However, no phage-specific mRNA or proteins are produced following an IPI- mutant infection. IPI- phages can complement other T4 amber mutants during a mixed infection of this host; however, when the T4 amber mutant is added, in the presence of chloramphenicol, 20 min after the IPI- phage, no complementation is observed. In the absence of IPI the entering DNA is degraded into acid-soluble fragments. It seems that it is the injected IPI that functions to allow infection of CT596, and that the block in infection occurs at some point between the injection of the phage DNA into this host and the beginning of phage mRNA synthesis. © 1979.