Engineered Proteins Mimic ssRNA Phage to Disrupt Type IV Pili

Antimicrobial resistance is a growing global health crisis, with ESKAPE pathogens, such as Acinetobacter species, contributing significantly to hospital-acquired infections. These bacteria employ various virulence factors, including extracellular type IV pili (T4P), which serve as essential appendages for DNA uptake, biofilm formation, and resistance to antibiotics. Single-stranded RNA (ssRNA) bacteriophages (phages) exploit these retractile pili as entry receptors, but the exact mechanism of viral RNA delivery following pilus binding and retraction remains poorly understood. In this study, we investigated the entry mechanism of the ssRNA phage AP205 by identifying the specific phage components necessary for T4P detachment, a key step in viral genome entry. Our data reveals the phage's maturation protein (Mat) is sufficient to induce pilus detachment on its own, and the overall virion structure further enhances the efficiency of this process. These findings provide mechanistic insights into how ssRNA phages exploit bacterial T4P as part of their infection pathway and suggest a conserved strategy for host entry.