A Filamentous Bacteriophage Protein Inhibits Type IV Pili To Prevent Superinfection of Pseudomonas aeruginosa

Pf bacteriophage (phage) are filamentous viruses that infect Pseudomonas aeruginosa and enhance its virulence potential. Pf virions can lyse and kill P. aeruginosa through superinfection, which occurs when an already infected cell is infected by the same or similar phage. Here, we show that a small, highly conserved Pf phage protein (PA0721, PfsE) provides resistance to superinfection by phages that use the type IV pilus as a cell surface receptor. PfsE does this by inhibiting assembly of the type IV pilus via an interaction with PilC. As the type IV pilus plays important roles in virulence, the ability of Pf phage to modulate its assembly has implications for P. aeruginosa pathogenesis.