Pseudomonas aeruginosa is a high-risk opportunistic pathogen causing hospital-acquired infections. Its filamentous phage Pf enhances biofilm integrity, pathogenicity, and antibiotic resistance. The excisionase XisF4, encoded by Pf4, is known to be a key protein in prophage excision and transcriptional regulation, yet its physicochemical properties, regulatory targets, functional mechanisms, and evolutionary traits remain unclear. This study aims to address these gaps.