The ability of Salmonella to survive and replicate within mammalian host cells involves the generation of a membranous compartment known as the Salmonella‐containing vacuole (SCV). Salmonella employs a number of effector proteins that are injected into host cells for SCV formation using its type‐3 secretion systems encoded in SPI‐1 and SPI‐2 (T3SS‐1 and T3SS‐2, respectively). Recently, we reported that S. Typhimurium requires T3SS‐1 and T3SS‐2 to survive in the model amoeba Dictyostelium discoideum. Despite these findings, the involved effector proteins have not been identified yet. Therefore, we evaluated the role of two major S. Typhimurium effectors SopB and SifA during D. discoideum intracellular niche formation. First, we established that S. Typhimurium resides in a vacuolar compartment within D. discoideum. Next, we isolated SCVs from amoebae infected with wild type or the ΔsopB and ΔsifA mutant strains of S. Typhimurium, and we characterised the composition of this compartment by quantitative proteomics. This comparative analysis suggests that S. Typhimurium requires SopB and SifA to modify the SCV proteome in order to generate a suitable intracellular niche in D. discoideum. Accordingly, we observed that SopB and SifA are needed for intracellular survival of S. Typhimurium in this organism. Thus, our results provide insight into the mechanisms employed by Salmonella to survive intracellularly in phagocytic amoebae.

中文翻译：

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社会变形虫盘基网柄菌中含沙门氏菌的液泡蛋白质组的 SopB 和 SifA 依赖性成形。

沙门氏菌在哺乳动物宿主细胞内存活和复制的能力涉及产生称为含沙门氏菌液泡 (SCV)的膜状隔室。沙门氏菌使用多种效应蛋白，这些效应蛋白被注入宿主细胞以使用其在 SPI-1 和 SPI-2（分别为 T3SS-1 和 T3SS-2）中编码的 3 型分泌系统形成 SCV。最近，我们报道了S . Typhimurium 需要 T3SS-1 和 T3SS-2 才能在模型变形虫盘基网柄菌中存活。尽管有这些发现，但尚未确定所涉及的效应蛋白。因此，我们评估了两个主要S的作用。鼠伤寒效应物 SopB 和 SifAd。椎间盘细胞内生态位形成。首先，我们确定了S。Typhimurium 位于D内的液泡室中。菌。接下来，我们从感染野生型或S的 Δ sopB和 Δ sifA突变株的变形虫中分离 SCV 。Typhimurium，我们通过定量蛋白质组学表征了该隔室的组成。这种比较分析表明S . Typhimurium 需要 SopB 和 SifA 来修改 SCV 蛋白质组，以便在D 中产生合适的细胞内生态位。椎间盘. 因此，我们观察到 SopB 和 SifA 是S 的细胞内存活所必需的。该生物体中的鼠伤寒杆菌。因此，我们的结果提供了对沙门氏菌在吞噬性变形虫中在细胞内存活的机制的深入了解。