The relationship between the transfer systems of some bacterial plasmids

Abstract

SUMMARYThe relationship between the transfer systems of several plasmids was investigated, using as criteria complementation of a series of transfer-deficientFlacmutants, the efficiency of plating of F-specific phages, and identification of surface exclusion systems. The transfer systems of ColV2 and ColVBtrpwere similar to that of F except for surface exclusion: ColVBtrpspecified a surface exclusion system different from that of F, and ColV2 did not specify any detectable system. The transfer system of R1–19 was also similar to that of Flac, but the products oftraA,traIandtraJwere plasmid-specific. R1–19 determined the same surface exclusion system as ColVBtrp, and this was under the control of the transfer inhibitor. The transfer systems of ColIbdrdandFlacwere unrelated. ColEl was transferred byFlac traI−mutants, but not by mutants in other cistrons.