[Plasmid recombination stimulated by restriction endonuclease EcoRI in vivo: formation of recombinant plasmids in recA+-cells of E. coli].

The possible participation of restriction endonuclease EcoRI in recombination of compatible nonhomologous plasmids in E. coli cells has been studied. To study the process, plasmids RP4 and R245 have been transferred by conjugation into the recipient cells of E. coli harbouring one of isogenic plasmids, pSA14 and pSA25, different for the genes coding restriction endonuclease EcoRI. The genetic analysis of transconjugant phenotypes, coded by the plasmids, has permitted to register the recombinant plasmids after compatibility of parent plasmids in E. coli cells. Recombination of plasmid RP4 with the plasmid pSA14, carrying EcoRI genes, has been registered in E. coli cells, producing the restriction endonuclease, while plasmid recombination has not been found in the cells harbouring plasmid pSA25, isogenic for all genes, except for EcoRI genes, with plasmid pSA14. Restriction endonuclease EcoRI is concluded to stimulate site specific recombination of nonhomologous compatible plasmids in vivo. EcoRI-mediated recombination of plasmid R245 with plasmid pSA14 is discussed.