The traA gene of the Enterococcus faecalis conjugative plasmid pPD1 encodes a negative regulator for the pheromone response.

The Enterococcus faecalis conjugative plasmid pPD1 (59 kb) produces an aggregation substance in response to pheromone. The traA gene (962 bp) is a member of a gene cluster involved in the regulation of the pPD1 pheromone response. A chimeric E. faecalis suicide plasmid containing a 762-bp DNA fragment from the middle portion of the traA gene was constructed. The pPD1 traA was disrupted by integration of this chimeric plasmid via homologous recombination. The E. faecalis strain containing pPD1 with the disrupted traA exhibited dry colony morphology, constitutive clumping, and an ability to transfer at high frequencies in a short (10-min) mating period, indicating that the traA product of pPD1 is a negative regulator for the pheromone response.