Premjani Veena, Tilley Derek, Gruenheid Samantha, Le Moual Hervé, Samis John A
Applied Biosciences Program, Faculty of Science, University of Ontario Institute of Technology, Oshawa, ON, Canada.
FEMS Microbiol Lett. 2014 Jun;355(2):185-92. doi: 10.1111/1574-6968.12463. Epub 2014 May 29.
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.
由食物或水引起的肠出血性大肠杆菌（EHEC）感染常导致严重腹泻疾病，是全球主要死因之一。大肠杆菌分泌的外膜囊泡（OMV）可诱导小鼠死亡。大肠杆菌的omptin外膜蛋白酶OmpT可使抗菌肽失活，并可能增强尿道上皮的定殖能力，但其确切功能尚不清楚。鉴于OmpT是一种外膜蛋白酶，我们推测它可能在OMV生物发生中起作用。为了进一步表征OmpT对OMV产生的影响，我们采用了一种遗传学方法，使用野生型、ompT缺失突变体和在EHEC中过表达ompT的构建体。ompT基因缺失显著降低了OMV的产生和可染色脂质，但增加了囊泡直径。相反，ompT过表达显著增加了OMV生物发生，但降低了可染色脂质、蛋白质含量和囊泡直径。EHEC中ompT基因表达的改变对OMV的生物发生、组成和大小有影响。ompT基因表达的变化可能会根据不同的宿主环境动态改变OMV的形成、组成和直径，并有助于无细胞的细胞间通讯，以增强细菌的生长和存活。
