SITE-SPECIFIC DELETIONS IN THE RECOMBINANT PLASMID PSC101 CONTAINING THE REDB-ORI REGION OF PHAGE-LAMBDA

Large deletions occur in the hybrid plasmid formed by pSC101 and the EcoRI fragment f2 of phage .lambda. (redB-ori region) under well defined growth conditions (Bernardi and Bernardi, 1980). The novel joints of the 4 deletions so obtained were sequenced; they have 1 endpoint in psC101, identical in all 4 cases, the other endpoint being located in 4 different .lambda. sequences. The nucleotide sequences of the novel joints show homologies between the conserved pSC101 sequence and the .lambda. sequences both conserved and deleted. The presence of an IS(insertion sequence)-type element in pSC101 is postulated; this element is unrelated to the 200-bp [base pair] element already described in pSC101 (Ravetch et al, 1976).