Kuehn, M. J. | bioRxiv Science

bioRxiv2026

Orchestration of Staphylococcus aureus EV biogenesis by nutrient availability through quorum sensing

The release of extracellular vesicles (EV) is a universally conserved process. Bacterial EVs package diverse cargo, including proteins and nucleic acids, and influence bacterial adaptation and survival as well as host-pathogen interactions. Currently, our understanding of the mechanisms underlying global principles in Gram-positive EV biogenesis and release is limited, partly due to labor-intensive vesicle isolation and assessment methods. Here, we describe a moderately high-throughput approach to analyze the Nebraska Transposon Mutant Library to identify genetic determinants of EV production in S. aureus. We show that the agr quorum sensing system dictates EV production in response to nutrient availability, likely through communication with the adaptive stress response. This study demonstrates the contribution of nutritional stress to vesiculogenesis and supports a conserved communication strategy that allows metabolic state to influence EV production.

microbiology↗

bioRxiv2020

Staphylococcus aureus secretes immunomodulatory RNA and DNA via membrane vesicles

Bacterial-derived RNA and DNA can function as ligands for intracellular receptor activation and induce downstream signaling to modulate the host response to bacterial infection. The mechanisms underlying the secretion of immunomodulatory RNA and DNA by pathogens such as Staphylococcus aureus and their delivery to intracellular host cell receptors are not well understood. Recently, extracellular membrane vesicle (MV) production has been proposed as a general secretion mechanism that could facilitate the delivery of functional bacterial nucleic acids into host cells. S. aureus produce membrane-bound, spherical, nano-sized, MVs packaged with a select array of bioactive macromolecules and they have been shown to play important roles in bacterial virulence and in immune modulation through the transmission of biologic signals to host cells. Here we show that S. aureus secretes RNA and DNA molecules that are mostly protected from degradation by their association with MVs. Importantly, we demonstrate that MVs can be delivered into cultured macrophage cells and subsequently stimulate a potent IFN-{beta} response in recipient cells via activation of endosomal Toll-like receptors. These findings advance our understanding of the mechanisms by which bacterial nucleic acids traffic extracellularly to trigger the modulation of host immune responses.

microbiology↗