Isolation and characterization of lambda phages carrying the basic replicon of the resistance plasmid R1

✍ Scribed by Dreisig, Hanne ;Riise, Erik ;Nordström, Kurt

• Publisher: Springer
• Year: 1981
• Tongue: English
• Weight: 607 KB
• Volume: 182
• Category: Article
• ISSN: 0026-8925
• DOI: 10.1007/bf00422782

✦ Synopsis

Specialized transducing lambda phages, 2 oriR1, harboring DNA from the resistance plasmid Rldrd-19 and its copy mutant pKN103 were isolated. From measurements of CCC-DNA content it is concluded that upon infection the phages can establish themselves as self-replicating plasmids in recA hosts lysogenic for lambda. It is thought that this bypassing of lambda immunity is due to the presence of the R1 origin of replication. The plasmids are sensitive to the incompatibility expressed by plasmid R1. This has been shown mainly by transduction of 2oriR1 into recipients containing R1 plasmids or plasmid pBR322 carrying the basic replicon. We were able to demonstrate that a copy mutant of plasmid Rt was insensitive to copA +, but sensitive to the conserted action of PstI fragments F1 and Fz. This mutant was previously assumed to be of the dominant type. Physical mapping of the 2oriRI derivatives verified that they carry the basic replicon of plasmid R1. The plasmids are not stably maintained, but are lost in a frequency of 1%-2% per cell generation, which is consistent with their lack of the Rlpar region.