Construction and properties of recombinant plasmids containing the rII genes of bacteriophage T4

The EcoRI digestion products of phage T4 DNA have been examined using a phage DNA transformation assay. A 2.6 X 10(6) Dalton fragment was found to contain the rII genes. This fragment was purified and then treated with HindIII endonuclease. The cleavage products were ligated to the vector plasmid pBR313 and viable recombinant plasmids recovered. A genetic assay was employed to demonstrate that the recombinants contained T4 DNA and to localize on the phage genetic map the EcoRI and HindIII sites cleaved during the construction of the plasmids. Preliminary characterization suggests that a fragment covering the beginning of the rIIA gene possibly contains a promotor which is active in uninfected cells.