The Salmonella-Containing Vacuole

鼠伤寒沙门氏菌是人类和牛小肠结肠炎的常见病因，但在易感小鼠中引起全身性伤寒样疾病。这种兼性细胞内病原体侵入非吞噬细胞，例如在肠上皮中发现的那些细胞，并在被称为含沙门氏菌空泡（SCV）的修饰的吞噬体内存活。两种III型分泌系统（T3 SS），其将不同的细菌效应蛋白质组易位到宿主细胞中，是建立细胞内复制环境所必需的。侵袭依赖于T3 SS 1，而T3 SS 2是在细胞内诱导的，并且与SCV的细胞内存活/复制和生物发生相关。为了了解沙门氏菌的发病机制，我们必须剖析T3 SS 1和T3 SS 2效应蛋白的作用，以及控制它们在宿主细胞内的表达和活性的机制。宿主-病原体相互作用的另一个重要方面是SCV的生物发生，从细菌的初始形成到最终释放。我们以前已经表明，SCV的生物发生涉及持续的动态相互作用与内吞途径，包括晚期内体和溶酶体。我们现在正集中精力在SCV形成的初始阶段，目标是获得详细的蛋白质组学数据的膜皱褶和新生的吞噬体。将跟踪这些组分中富集的宿主细胞蛋白，以确定它们在该过程中的作用。

Salmonella enterica serovar Typhimurium is a common cause of enterocolitis in humans and cattle but causes a systemic, typhoid-like, disease in susceptible mice. This facultative intracellular pathogen invades non-phagocytic cells, such as those found in the intestinal epithelium, and survives within a modified phagosome known as the Salmonella-containing vacuoles (SCV). Two type III secretion systems (T3SS), which translocate distinct cohorts of bacterial effector proteins into the host cell, are required for establishment of the intracellular replicative environment. Invasion is dependent on T3SS1 whereas T3SS2 is induced intracellularly and is associated with intracellular survival/replication and biogenesis of the SCV. To understand Salmonella pathogenesis we must dissect the roles of the individual T3SS1 and T3SS2 effector proteins as well as the mechanisms that control their expression and activity inside host cells. Another important aspect of the host-pathogen interaction is the biogenesis of the SCV, from initial formation through to the ultimate release of bacteria. We have previously shown that SCV biogenesis involves sustained dynamic interactions with the endocytic pathway including late endosomes and lysosome. We are now focusing our efforts on the initial stages of SCV formation, with the goal of obtaining detailed proteomics data on the membrane ruffles and nascent phagosome. Host cell proteins enriched in these fractions will be followed up to establish their roles in the process.