Proteomic Analysis of Vesicle-Producing PAO1 Exposed to X-Ray Irradiation.

Ionizing irradiation kills pathogens by destroying nucleic acids without protein structure destruction. However, how pathogens respond to irradiation stress has not yet been fully elucidated. Here, we observed that PAO1 could release nucleic acids into the extracellular environment under X-ray irradiation. Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray irradiation was observed to induce outer membrane vesicle (OMV) formation in PAO1. The size distribution of the OMVs of the irradiated PAO1 was similar to that of the OMVs of the non-irradiated PAO1 according to nanoparticle tracking analysis (NTA). The pyocin-related proteins are involved in OMV production in PAO1 under X-ray irradiation conditions, and that this is regulated by the key SOS gene . The OMV production was significantly impaired in the irradiated PAO1 Δ mutant, suggesting that Lys endolysin is associated with OMV production in PAO1 upon irradiation stress. Meanwhile, no significant difference in OMV production was observed between PAO1 lacking the , , or genes and the parent strain, demonstrating that the irradiation-induced OMV biosynthesis of was independent of the quinolone signal (PQS).