PLASMID RP4, WITH ESCHERICHIA-COLI DNA INSERTED INVITRO, MEDIATES CHROMOSOMAL TRANSFER

The wide host-range plasmid RP4 is generally poor at mobilizing chromosomal markers. Insertion in vitro of Escherichia coli chromosomal DNA into its HindIII site (recognized by loss of its kanamycin resistance marker) or its EcoRI site generated RP4-primes that efficiently mobilized chromosomal markers. These RP4-primes behaved analogously to F-primes, each had a particular transfer origin and direction of marker mobilization, and this was abolished by a recA allele in the donor. Insertion sequences on the RP4-primes do not appear to be necessary for mobilization, it seems very unlikely that each of the RP4-primes generated contained an insertion sequence. The construction and use of such plasmids should facilitate inter- and intrageneric genetic analyses and manipulations. © 1979.