The PerA regulon in Enterococcus faecalis

Transcriptional profiling of E. faecalis E99 WT and an isogenic ΔperA strain grown in THB + 1% glucose. Pathogenic E. faecalis are enriched for a pathogenicity island (PAI). This 150-kb island harbors a number of well characterized virulence genes plus a number of determinants of unknown function including one encoding a transcriptional regulator, designated PerA. In this work, we show that PerA coordinately regulates both metabolic and virulence genes, and influences the platelet binding ability of E. faecalis. Finally, we show that PerA responds to bicarbonate, an intestinal ion frequently used by pathogens to determine the site of infection. Together, these results indicate that PerA is a global transcriptional regulator that coordinately regulates genes responsible for enterococcal pathogenicity. These findings highlight a novel feature of PAI-mediated virulence regulation, namely the coordinate regulation of metabolic and virulence factors in the core genome by a horizontally acquired PAI-encoded transcriptional regulator. RNA was obtained from E. faecalis E99 ΔperA from mid-log (OD600 0.05), late log (OD600 0.5) and stationary phase (OD600 1.0) and compared to E. faecalis E99 WT RNA extracted from the same growth phases. Cultures were grown in THB + 1% glucose.