pHG276: a multiple cloning site pBR322 copy number vector expressing a functional lac alpha peptide from the bacteriophage lambda PR promoter.

The bacteriophage lambda early promoter PR has been used to direct the synthesis of lac alpha in a plasmid containing the multiple cloning site of pUC8. The copy number of the plasmid is controlled by the rop(rom) gene and the plasmid incorporates the cI857 gene for temperature regulation of lac alpha expression. Isolation of recombinant derivatives with DNA inserts in the multiple cloning region can be identified by insertional inactivation of lac alpha and consequently, a Lac- phenotype in a host carrying the M15 deletion of lac. The potential of pHG276 as a fully regulated expression vector is examined.