Cloned genes for bacteriophage T4 late functions are expressed in Escherichia coli

We have constructed derivatives of plasmid pMB9 carrying EcoRI digestion fragments of bacteriophage T4 DNA that code for late gene functions. When Escherichia coli strains carrying these plasmids are infected with T4 amber mutants, burst sizes up to 30% of the wild-type level are obtained. Single burst experiments imply that the phage progeny result from complementation and do not depend on marker rescue. By electrophoretic and immunological techniques, we have established that the cloned T4 late genes are transcribed and translated in uninfected cells. A serum blocking assay has been used to quantitate the levels of one of the T4 gene products, gp11, before and after T4 infection. Uninfected cells containing the cloned T4 gene 11 DNA have 0.1% and mini cells have 1% of the gp11 levels per unit protein found in cells late after T4 wild-type infection. There is little or no additional gp10 and gp11 formed from the cloned genes after T4 infection.