Construction of recombinant lambda phages that carry the E. coli recB and recC genes.

A fragment of the E. coli chromosome including the recC gene has been cloned by in vitro recombinant DNA techniques into a phage lambda vector to give the recombinant phage lambda drecC. This was used to derive the phage lambda drecBC by in vivo recombination. On lysogenisation of recB and recC mutants with lambda drecBC wild levels of UV-resistance and RecBC DNase activity were restored. Infection of E coli with lambda drecBC led to the synthesis of phage-coded proteins of 125 kilodaltons (kd) and 135 kd that were not synthesised on infection with the original lambda vector, whereas a 125 kd protein but not a 135 kd protein was synthesised in similar experiments with lambda drecC. The recombinant phages, which are unable to form plaques, presumably due to the deletion of essential phage genes during their construction, provided useful starting points from which to subclone the recB, recC, and the neighbouring thyA and argA genes individually into multiple copy plasmid vectors.