[Characteristics of the deletion mutant of plasmid R6K]

Deletion plasmide R6Kdelta with the mol wt of 17.2.10(6) dalton isolated from the E. coli chi 925 (R6K) is described. This plasmide expresses no resistance to streptomycin, is replicated in the E. coli K12 under relaxed control and is resistant to the treatment with the eliminating agents. Analysis of plasmide DNA with the aid of electrophoresis in agarose gel demonstrated that R6K delta has one site attacked by restriction endonucleases Eco. RI and Bam HI. These data were confirmed by the determination of the transforming activity of the corresponding DNA restrictors. It is supposed that the isolated plasmide was identical with plasmide RSF1040. A possibility of using R6K delta as a genetic vector for obtaining recombination DNA molecules in vitro is discussed.