Enterohemorrhagic Escherichia coli OmpT regulates outer membrane vesicle biogenesis

Enterohemorrhagic Escherichia coli (EHEC) infection from food or water often results in severe diarrheal disease and is a leading cause of death globally. Outer membrane vesicles (OMVs) secreted from E.coli induce lethality in mice. The omptin outer membrane protease OmpT from E.coli inactivates antimicrobial peptides and may enhance colonization of the uroepithelium, but its precise function remains unclear. Given OmpT is an outer membrane protease, we hypothesized it may have a role in OMV biogenesis. To further characterize the effect of OmpT on OMV production, a genetic approach using wild type, an ompT deletion mutant and an ompT overexpressing construct in EHEC were employed. ompT gene deletion markedly decreased OMV production and stainable lipid but increased vesicle diameter. Conversely, ompT overexpression profoundly increased OMV biogenesis but decreased stainable lipid, protein content, and vesicle diameter. Alterations in EHEC ompT gene expression have an impact on the biogenesis, composition, and size of OMVs. Changes in ompT gene expression may dynamically alter OMV formation, composition, and diameter in response to different host environments and contribute to cell-free intercellular communication to enhance bacterial growth and survival.