Department of Clinical Microbiology and Immunology, Southwest Hospital and College of Medical Laboratory Science, Third Military Medical University, Chongqing 400038, P.R. China.
National Engineering Research Center for Immunobiological Products, Department of Microbiology and Biochemical Pharmacy, College of Pharmacy, Third Military Medical University, Chongqing 400038, P.R. China.
Mol Med Rep. 2017 Aug;16(2):1544-1550. doi: 10.3892/mmr.2017.6763. Epub 2017 Jun 13.
The translocated intimin receptor (Tir) is a canonical type III secretion system effector, secreted by the enterohemorrhagic Escherichia coli (E. coli). This receptor alters the regular cellular processing of host cells, to promote intracellular bacterial replication and evasion of the host immune system. Tir is translocated and integrated into the host cell plasma membrane, a process required for its pathogenic activity in these cells, however, the underlying mechanisms of how this occurs remain to be elucidated. The present study used immunofluorescence and immunoelectron microscopy to demonstrate that the Tir of enterohemorrhagic E. coli was localized to the plasma membrane and colocalized with the 58K Golgi protein of the host cells. Treatment with brefeldin A destroyed the Golgi structure, inhibited the formation of actin pedestal and blocked the localization of Tir on the host cell plasma membrane. The results of the present study suggested that Tir is translocated to the host plasma membrane in a Golgi‑dependent manner. It may mimic the activities of eukaryotic secretory proteins in order to make use of the Golgi apparatus for transportation and integration into the plasma membrane. These findings reveal a novel trafficking pathway for the translocation of bacterial secretory effectors to their specific subcellular compartments.
易位性紧密素受体（Tir）是一种典型的 III 型分泌系统效应蛋白，由肠出血性大肠杆菌（E. coli）分泌。该受体改变宿主细胞的常规细胞处理过程，促进细胞内细菌复制并逃避宿主免疫系统。Tir 易位并整合到宿主细胞膜中，这是其在这些细胞中致病活性所必需的过程，但这一过程的潜在机制仍有待阐明。本研究采用免疫荧光和免疫电子显微镜技术证明，肠出血性大肠杆菌的 Tir 定位于质膜，并与宿主细胞的 58K Golgi 蛋白共定位。布雷菲德菌素 A 的处理破坏了高尔基体结构，抑制了肌动蛋白足的形成，并阻断了 Tir 在宿主细胞膜上的定位。本研究的结果表明，Tir 以依赖高尔基体的方式易位到宿主质膜上。它可能模拟真核分泌蛋白的活性，以便利用高尔基体进行运输并整合到质膜中。这些发现揭示了细菌分泌效应蛋白向其特定亚细胞隔室转移的新运输途径。
