RNAs Associated With Bacterial Outer Membrane Vesicles: Structural Insights Into Surface Composition

Gram-negative bacteria release outer membrane vesicles (OMVs) that deliver various molecules, including virulence factors, allowing them to interact with their host. Recent evidence suggests that OMVs may serve as carriers for RNAs, in particular small regulatory noncoding RNAs (sRNAs). However, for these sRNAs to function effectively, they often require a protein cofactor, typically the Hfq RNA chaperone. In our previous studies, we demonstrated that Hfq, after interacting with the bacterial inner membrane, can be translocated to the periplasm and subsequently exported within OMVs, potentially in association with RNAs. In the present study, we build upon this previous work and provide evidence that RNA molecules are not only a key component of the OMV lumen, but can also be inserted into the vesicle membrane in an Hfq-dependent manner. This new finding suggests that surface-presented RNAs may be directly delivered to the host. Overall, our results reveal a previously unrecognized aspect of OMV-associated RNA and emphasizes the need to explore the role of RNAs in cell-to-cell communication, as OMV-host interplay may not be governed solely by protein-protein or protein-membrane contacts.