Characteristics of derivatives of the plasmid RP4 in a broad range of hosts with altered properties of maintenance and inheritance

Hydroxylamine-induced mutants of the plasmid pPD6 (8.4 kb) were isolated which are resistant to high doses of tetracycline. One of the plasmids studied--pPD21 is a multicopy mutant, another one, pPD12 is a dimeric form of the pPD6 plasmid. The pPD12 plasmid is very unstable, its derivative, pPD13 spontaneous mutant acquiring stability but not the ability to resolve DNA multimeric forms into monomeric forms. Multicopy bireplicon pPD619 plasmid was constructed by joining in vitro pPD6 and pUC19 plasmids. Removing the replicon pUC19 from the bireplicon plasmid gives a new low-copy plasmid pPD620. All of the plasmids constructed were mobilized by the conjugative pRK2013 plasmid into the strains of Escherichia coli, Pseudomonas aeruginosa and Agrobacterium tumefaciens. The pPD6 plasmid and its derivatives can be used as cloning vectors.