Lysis Physiology of Pseudomonas aeruginosa Infected with ssRNA Phage PRR1

Area of Science:

• Microbiology
• Virology
• Molecular Biology

Background:

• Phage PRR1 is an ssRNA bacteriophage from the Leviviridae family.
• It infects Gram-negative bacteria by targeting pili encoded by IncP-type plasmids, which often confer antibiotic resistance.
• Understanding phage-host interactions is crucial for developing novel antimicrobial strategies.

Purpose of the Study:

• To investigate the PRR1 phage infection cycle in *Pseudomonas aeruginosa* PAO1, with a specific focus on the mechanism of cell lysis.
• To determine the host physiological factors influencing PRR1-mediated lysis.
• To elucidate the role of aeration in the phage infection and lysis process.

Main Methods:

• On-line monitoring of the PRR1 infection cycle in *P. aeruginosa* PAO1.
• Analysis of cell sensitivity to lysozyme and accumulation of lipophilic anions post-infection.
• Investigating the impact of respiration blockage, reduced intracellular ATP, and aeration levels on lysis.
• Induction of PRR1 lysis protein synthesis in an *E. coli* expression system.

Main Results:

• PRR1 infection sensitizes *P. aeruginosa* to lysozyme and causes lipophilic anion accumulation ~20 minutes before turbidity drop.
• Cell lysis is dependent on host cell physiological state, inhibited by respiration blockage or reduced ATP levels.
• Lysis is strongly coupled to aeration levels; sufficient oxygen for growth does not guarantee efficient lysis.
• Inducing PRR1 lysis protein in *E. coli* also resulted in inhibited lysis, suggesting host factors are critical.

Conclusions:

• Phage PRR1-mediated cell lysis is an active, energy-dependent process requiring specific host physiological conditions and adequate aeration.
• The efficiency of lysis is modulated by host respiration and ATP levels, not solely by the presence of the lysis protein.
• These findings provide insights into bacteriophage biology and potential targets for phage therapy optimization.