Assembly of functional bacteriophage lambda virions incorporating C-terminal peptide or protein fusions with the major tail protein.

The tolerance of bacteriophage lambda morphogenesis for C-terminal additions to the tail tube major protein subunit (the V gene product; gpV) has been investigated. A second modified copy of the lambda V gene, either within a novel phage vector itself or plasmid-borne, was expressed during phage growth. High-level substitution of wild-type gpV by modified gpV bearing a basic C-terminal peptide sequence (RRASV; a target site for cAMP-dependent protein kinase) was possible using multiple repeats of a serine-glycine (SGGG) linker sequence. Highly purified phage bearing copies of gpV-RRASV could be efficiently phosphorylated by the appropriate protein kinase, and the incorporated label was shown to migrate exclusively at the expected size in protein gels. A large tetrameric protein (beta-galactosidase) could be incorporated into active virions in at least one copy, again using a Ser-Gly linker. These studies suggest that with a suitable spacing linker and controlled levels of expression, it is likely that a wide range of protein or peptide substitutents can be fused with gpV at its C terminus and assembled as component subunits of the tail tube.