The RNA Complement of Outer Membrane Vesicles From

Area of Science:

• Microbiology and Molecular Biology
• Bacterial Pathogenesis
• Extracellular Vesicle Biology

Background:

• Bacterial outer membrane vesicles (OMVs) and their small RNAs are implicated in host-pathogen interactions.
• The role of larger RNA transcripts within OMVs during infection remains largely unexplored.

Purpose of the Study:

• To analyze the composition and characteristics of RNA within OMVs secreted by Salmonella Typhimurium under various conditions mimicking host-pathogen interactions.
• To investigate the potential for OMVs to protect RNA transcripts from degradation and facilitate their extracellular transport.

Main Methods:

• Salmonella Typhimurium cultured in minimal (PCN) and rich (LB) media under conditions inducing Salmonella Pathogenicity Islands 1 and 2 (SPI-1, SPI-2).
• Analysis of OMV-associated RNA, comparing extracellular and intracellular RNA profiles using RNA sequencing.
• Confirmation of RNA integrity (full-length vs. processed) via PCR and assessment of OMV protection against enzymatic degradation.

Main Results:

• OMVs secreted by S. Typhimurium contained diverse RNA classes, including rRNA, mRNA, and ncRNA, with proportions varying based on growth conditions.
• Specific mRNAs and ncRNAs were enriched in OMVs under different culture conditions, indicating selective packaging.
• OMVs protected certain full-length RNA transcripts (e.g., SsrS, CsrC, 10Sa, rnpB) from enzymatic degradation.

Conclusions:

• OMV-associated RNA profiles differ significantly depending on bacterial growth conditions.
• A portion of extracellular RNA is associated with OMVs as full-length transcripts, suggesting a protective role for OMVs.
• OMV-mediated RNA protection opens possibilities for functional roles in host-pathogen communication.