Proteomic Profiling Reveals Distinct Bacterial Extracellular Vesicle Subpopulations with Possibly Unique...

Area of Science:

• Microbiology
• Plant Pathology
• Biochemistry

Background:

• Bacterial outer membrane vesicles (OMVs) mediate interkingdom communication between bacteria and plants.
• OMVs from pathogenic and beneficial strains elicit plant immune responses, influencing seedling growth and pathogen defense.
• Previous research indicates differences in OMV protein composition between Pseudomonas syringae and Pseudomonas fluorescens, affected by culture conditions.

Purpose of the Study:

• To investigate the impact of different medium conditions on the protein cargo of OMVs from pathogenic (P. syringae) and beneficial (P. fluorescens) bacteria.
• To identify proteins associated with OMV-mediated bacterial virulence, plant immune activation, and bacterial stress tolerance.
• To explore potential differences in vesicle biogenesis and cargo loading between pathogenic and beneficial bacteria.

Main Methods:

• Culturing Pseudomonas syringae and Pseudomonas fluorescens in complete and minimal media mimicking the plant apoplast.
• Comparative proteomic analysis of OMVs isolated from bacteria grown under different conditions.
• Bioinformatic analysis, including localization enrichment, to identify protein functions and potential vesicle subpopulations.

Main Results:

• Minimal medium conditions significantly altered OMV protein content in P. syringae but not P. fluorescens.
• Specific protein subsets were linked to bacterial virulence, plant immune activation, and bacterial stress tolerance.
• Analysis suggested the presence of outer-inner membrane vesicles (OIMVs) involved in bacterial stress responses.

Conclusions:

• Distinct bacterial extracellular vesicle populations with diverse functional roles exist, influenced by medium conditions.
• Pathogenic and beneficial bacteria exhibit different strategies for vesicle cargo loading and biogenesis in response to environmental cues.
• OMVs are implicated in virulence, while OIMVs are associated with bacterial stress tolerance in plant-associated bacteria.