The relationship between the transfer systems of some bacterial plasmids

Abstract

SUMMARY The relationship between the transfer systems of several plasmids was investigated, using as criteria complementation of a series of transfer-deficient Flac mutants, the efficiency of plating of F-specific phages, and identification of surface exclusion systems. The transfer systems of ColV2 and ColVB trp were similar to that of F except for surface exclusion: ColVB trp specified 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 F lac , but the products of traA , traI and traJ were plasmid-specific. R1–19 determined the same surface exclusion system as ColVB trp , and this was under the control of the transfer inhibitor. The transfer systems of ColIb drd and Flac were unrelated. ColEl was transferred by Flac traI − mutants, but not by mutants in other cistrons.