Stabilisation of plasmid(s) - by insertion of DNA fragment expressing partitioning fragment

摘要

Plasmid carrying an inserted gene(s) not naturally related to the plasmid as well as an inserted DNA fragment expressing a partitioning fragment is new. Plasmid carrying an inserted DNA fragment shorter than the EcoR1-A fragment of plasmid R1 and contg. a R1 par region is new. Bacterium harbouring a plasmid as defined above is new. Prodn. of a gene prod. of plasmid DNA comprises cultivation of a bacterium as defined above, and the prod. is harvested from the bacterial culture. DNA fragment comprising as its major component a R1 par region is new. Method of screening for the correct insertion of a par region in a plasmid (believed to carry such a region) comprises transformation to a bacterium already harbouring another unrelated plasmid carrying the same par region, as well as mediating a phenotype recognisable on approp. media. The correct insertion is identified as the loss of this phenotype. The stabilised plasmids are useful as cloning or prodn. vectors in recombinant DNA technology for prodn. of genes and their prods., e.g. polypeptides and proteins esp. enzymes and hormones, and nucleic acids.