Entry exclusion activity on conjugative plasmid pVT745.

Conjugative plasmid transfer into a recipient cell containing the same or a closely related plasmid is inhibited by a mechanism called entry or surface exclusion. The function of entry exclusion is to reduce unproductive conjugation. The current study assessed the exclusion activity on conjugal plasmid pVT745 by conducting mating experiments with genetically distinguishable derivatives of this plasmid. Our results demonstrate that a single gene, magB05, that is located in a gene cluster associated with mating pore formation, is responsible for the entry exclusion phenotype of pVT745.