Oxacillin promotes membrane vesicle secretion in a SarA-Sle1 regulatory cascade.

Membrane vesicles (MVs) are nanoscale particles secreted by living bacteria and . Bacterial MVs encapsulate various proteins, making them promising candidates for developing vaccines, drug carriers, and cancer immunotherapy agents. However, the mechanisms underlying MV secretion in Gram-positive bacteria remain unclear. Here, we showed that the subinhibitory concentration of oxacillin (OXA) stimulated MV production in with diverse genetic backgrounds. OXA treatment remarkably increased the expression of , which encodes a main peptidoglycan hydrolase for adjusting peptidoglycan cross-linking. Deletion of decreased the OXA-mediated MV yield, whereas overexpression of considerably increased MV production. The accessory regulator SarA increased in response to OXA treatment, and SarA inactivation substantially attenuated OXA-stimulated MV production. We also demonstrated that SarA controlled expression by directly binding to its promoter region. Thus, the SarA-Sle1 regulatory axis was formed to mediate OXA-induced MV production in . MVs derived from OXA-treated RN4220 (MVs/OXA) exhibited a smaller particle size compared with those purified from wild-type RN4220; however, proteomic analysis revealed a comparable protein profile between MVs and MVs/OXA. Overall, our research reveals a mechanism underlying OXA-promoted MV secretion and highlights the potential application of OXA-induced MVs.