Group of Molecular Cytology of Prokaryotes and Bacterial Invasion, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia.
Cell Biol Int. 2020 Nov;44(11):2275-2283. doi: 10.1002/cbin.11435. Epub 2020 Aug 12.
Serratia grimesii are facultative pathogenic bacteria that can penetrate a wide range of host cells and cause infection, especially in immunocompromised patients. Previously, we have found that bacterial metalloprotease grimelysin is a potential virulence determinant of S. grimesii invasion (E. S. Bozhokina et al., (2011). Cell Biology International, 35(2), 111-118). Protease is characterized as an actin-hydrolyzing enzyme with a narrow specificity toward other cell proteins. It is not known, however, whether grimelysin is transported into eukaryotic cells. Here, we show, for the first time, that S. grimesii can generate outer membrane vesicles (OMVs) displayed specific proteolytic activity against actin, characteristic of grimelysin. The presence of grimelysin was also confirmed by the Western blot analysis of S. grimesii OMVs lysate. Furthermore, confocal microscopy analysis revealed that the S. grimesii grimelysin-containing OMVs attached to the host cell membrane. Finally, pretreatment of HeLa cells with S. grimesii OMVs before the cells were infected with bacteria increased the bacterial penetration several times. These data strongly suggest that protease grimelysin promotes S. grimesii internalization by modifying bacterial and/or host molecule(s) when it is delivered as a component of OMVs.
斯氏普罗威登斯菌是一种兼性致病细菌，能够穿透广泛的宿主细胞并引起感染，特别是在免疫功能低下的患者中。此前，我们发现细菌金属蛋白酶格里姆利森是斯氏普罗威登斯菌侵袭的一个潜在毒力决定因素（E. S. Bozhokina 等人，（2011 年）。细胞生物学国际，35(2)，111-118）。蛋白酶的特点是一种肌动蛋白水解酶，对其他细胞蛋白具有狭窄的特异性。然而，目前尚不清楚格里姆利森是否被运送到真核细胞中。在这里，我们首次表明，斯氏普罗威登斯菌可以产生外膜囊泡（OMV），这些囊泡显示出针对肌动蛋白的特定蛋白水解活性，这是格里姆利森的特征。Western blot 分析斯氏普罗威登斯菌 OMV 裂解物也证实了格里姆利森的存在。此外，共聚焦显微镜分析显示，含有格里姆利森的斯氏普罗威登斯菌 OMV 附着在宿主细胞膜上。最后，在用细菌感染细胞之前，用斯氏普罗威登斯菌 OMV 预处理 HeLa 细胞会使细菌穿透增加数倍。这些数据强烈表明，当作为 OMV 的一部分被递送到细胞中时，蛋白酶格里姆利森通过修饰细菌和/或宿主分子来促进斯氏普罗威登斯菌的内化。
