The invasion-associated type III secretion system of Salmonella enterica serovar Typhimurium is necessary for intracellular proliferation and vacuole biogenesis in epithelial cells
The invasion-associated type III secretion system of Salmonella enterica serovar Typhimurium is necessary for intracellular proliferation and vacuole biogenesis in epithelial cells
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DOI：
10.1046/j.1462-5822.2002.00170.x
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发表时间：
2002-01-01
影响因子：
3.4
通讯作者：
Finlay, BB
中科院分区：
文献类型：
--
作者：
Steele-Mortimer, O;Brumell, JH;Finlay, BB
III型分泌系统（TTSS）被革兰氏阴性病原体用于将蛋白质转运到真核宿主细胞中。肠炎沙门氏菌血清型鼠伤寒沙门氏菌（S. Typhimurium）具有两个这样的专门系统，它们在单独的沙门氏菌致病性岛（SPI-1和SPI-2）上编码，并转运独特的效应物组。这些系统在沙门氏菌发病机制中的具体作用尚不清楚，尽管SPI-1是细菌侵袭上皮细胞所必需的，而SPI-2是吞噬细胞存活/复制所必需的。然而，由于SPI-1 TTSS突变体不具备入侵能力，因此该TTSS在入侵后过程中的作用尚未得到研究。在这项研究中，我们使用了两种不同的方法将非侵入性SPI-1 TTSS突变体（invA）内化到培养的上皮细胞中：(i)与野生型鼠伤寒沙门氏菌（SPI-1依赖）共内化，（ii）与假结核耶尔森菌入侵基因（inv）互补（SPI-1独立）。在这两种情况下，内化的invA突变体都不能在细胞内复制，这表明SPI-1效应物在这一过程中是必不可少的，并且不能被野生型细菌补充到同一细胞中。scv的生物发生分析表明，含有突变细菌的液泡表现出依赖于进入机制的异常成熟。通过药理学干扰宿主细胞中的膜运输来操纵含沙门氏菌液泡（SCV）的生物生成，增加了野生型而非突变型鼠伤寒沙门氏菌的细胞内复制。这证明了SPI-1在非吞噬细胞液泡生物生成和细胞内存活中的未知作用。
Type III secretion systems (TTSS) are used by Gram-negative pathogens to translocate proteins into eukaryotic host cells. Salmonella enterica serovar Typhimurium (S. Typhimurium) has two of these specialized systems, which are encoded on separate Salmonella pathogenicity islands (SPI-1 and SPI-2) and translocate unique sets of effectors. The specific roles of these systems in Salmonella pathogenesis remain undefined, although SPI-1 is required for bacterial invasion of epithelial cells and SPI-2 for survival/replication in phagocytic cells. However, because SPI-1 TTSS mutants are invasion-incompetent, the role of this TTSS in post-invasion processes has not been investigated. In this study, we have used two distinct methods to internalize a non-invasive SPI-1 TTSS mutant (invA) into cultured epithelial cells: (i) co-internalization with wild-type S. Typhimurium (SPI-1-dependent) and (ii) complementation with the Yersinia pseudotuberculosis invasin (inv) gene (SPI-1-independent). In both cases, internalized invA mutants were unable to replicate intracellularly, indicating that SPI-1 effectors are essential for this process and cannot be complemented by wild-type bacteria In the same cell. Analysis of the biogenesis of SCVs showed that vacuoles containing mutant bacteria displayed abnormal maturation that was dependent on the mechanism of entry. Manipulation of Salmonella-containing vacuole (SCV) biogenesis by pharmacologically perturbing membrane trafficking in the host cell increased intracellular replication of wild-type but not mutant S. Typhimurium This demonstrates a previously unknown role for SPI-1 in vacuole biogenesis and intracellular survival in non-phagocytic cells.