Infections caused by enterococci are a serious threat to human health, as they are a leading cause of hospital-associated infections in the United States and around the world. During infection, organisms rely on communication signals to ascertain population density, which enables a coordinated genetic response to assist in pathogenesis. Enterococcus faecalis relies on a variety of peptide signals to coordinate the appropriate response, enabling colonization and infection. Our lab has investigated two unique types of peptide signals that facilitate steps in pathogenesis. The Fsr quorum sensing system senses a cyclic peptide, termed GBAP, that activates expression of secreted proteases as well as a novel bacteriocin. We have also examined mechanisms related to cell-cell signaling as it pertains to horizontal gene transfer in E. faecalis and discovered a peptide transporter, termed PptAB, responsible for the active secretion of linear peptides used as pheromones to induce a conjugative mating response.
More recently, we have focused our attention on a family of transcription factors that are predicted members of the RRNPP family, which are thought to respond to linear peptide signals. I will discuss one such transcription factor that contributes to biofilm development and pathogenesis in a catheter associated urinary tract infection model.