Interplasmidic and intraplasmidic recombination in Escherichia coli K-12

The construction of plasmids which facilitate the study of interplasmidic and intraplasmidic recombination is described. In this system, a single recombination event between two mutated Tcr genes on separate plasmids or on one plasmid leads to a change in the host phenotype from sensitivity to resistance to tetracycline. Recombination proficiencies have been determined for different E. coli K-12 strains: both interplasmidic and intraplasmidic recombination are independent of the recBC gene product. RecA mutations decrease the proficiency of plasmidic recombination 40 - 100 fold. Intraplasmidic and interplasmidic recombination via the recE pathway are more efficient than via the recBC pathway. Intraplasmidic recombination, but not interplasmidic recombination via the recE pathway is independent of a functional recA product.