Expression of F plasmid trat: Independence of tray → z promoter and traJ control

We have shown, using an F-derived Tra + cosmid in conjunction with the infected-cell translational system and a time-course study, that one of the surface exclusion genes, traT, can be expressed independently of the promoter of the traY → Z operon, P YZ, and in the absence of a normal quantity of traJ gene product. Studies with deleted derivatives of the cosmid pRS2405 confirmed this independence and also indicated that expression of traD can be independent of P YZ-We propose that the expression of traT by these deleted plasmids is directed from a traJ-independent promoter, P T, located adjacent to traT.