Natural and synthetic inhibitors of a phage-encoded quorum-sensing receptor affect phage-host dynamics in mixed...

Area of Science:

• Microbiology
• Virology
• Molecular Biology

Background:

• Bacteriophages (viruses infecting bacteria) are key drivers of bacterial evolution and community structure.
• Temperate phages, as prophages within bacteria, can manipulate bacterial quorum sensing (QS), a cell-to-cell communication system.
• Gram-negative bacteria use N-acyl homoserine lactones (HSL) as autoinducers (AI) for QS, detected by LuxR-type receptors.

Purpose of the Study:

• To investigate how phage LuxRARM81ld, a QS receptor homolog encoded by phage ARM81ld, is modulated by different HSL ligands.
• To determine the effect of noncognate HSLs and a synthetic inhibitor on LuxRARM81ld activity and phage-induced lysis.
• To explore the ecological implications of HSL-mediated phage-host interactions in aquatic bacterial communities.

Main Methods:

• Characterization of phage LuxRARM81ld activity using various HSL ligands, including those produced by coexisting bacteria.
• Assessment of the impact of HSLs on phage-induced bacterial lysis and virion production.
• Coculture experiments with Aeromonas sp. ARM81 lysogens and Vibrio fischeri to observe community-level effects.

Main Results:

• Phage LuxRARM81ld activity is modulated by noncognate HSL ligands and a synthetic inhibitor.
• HSL molecules with acyl chain lengths of C8 or longer antagonize LuxRARM81ld function.
• Vibrio fischeri-produced C8-HSL inhibits LuxRARM81ld, protecting Aeromonas sp. ARM81 from phage-induced lysis and reducing virion production.

Conclusions:

• Bacterial autoinducers can act as antagonists of phage-encoded QS receptors, influencing phage-host dynamics.
• Interactions between bacterial species and their phages are influenced by the chemical communication landscape.
• Community composition and cell density may dictate the outcomes of bacterial-phage partnerships in aquatic environments.