Regulation of filamentous phage Pf4 activation by oxidative stress in Pseudomonas aeruginosa.

Abstract

The filamentous prophage Pf4 is activated to produce phage virions during Pseudomonas aeruginosa biofilm formation, a process crucial for maintaining biofilm architecture and enhancing pathogenicity. However, the environmental cues triggering Pf4 activation have been inadequately explored. In this study, we discovered that oxidative stress, a significant stressor encountered by pathogens in biofilms or within eukaryotic hosts, triggers the production of the filamentous phage Pf4 in P. aeruginosa MPAO1 through OxyR. Under oxidative stress, the expression of oxyR is induced, leading to increased OxyR binding to the promoter region of the Pf4 excisionase gene xisF4, thereby facilitating Pf4 prophage excision and virion production. Thus, our study elucidates a mechanism by which bacteria exploit cytotoxic oxidative stress as a potent stimulant to activate the filamentous phage Pf4 within biofilms.