Effector-mediated Ubiquitin Manipulation in Legionella Pneumophila Pathogenesis

项目摘要 宿主功能的主动调节是细菌病原体成功的关键。无所不在的 网络实际上调控着真核生物中的每一个细胞过程，特别是那些参与检测的过程， 对感染的识别和反应。因此，许多病原体针对宿主也就不足为奇了。 为了他们的利益而泛素化。早期的研究表明，嗜肺军团菌是引起 军团病通过使用至少9个Dot/ICM效应器来干扰宿主泛素信号传递。我们的 最近的研究发现，副作用家族的成员是独特的泛素操纵酶。 首先，这些蛋白质含有一个去泛素酶基序，可以攻击泛素化的蛋白质。第二，这些 蛋白质通过一种不寻常的机制催化泛素化：该反应不需要E1、E2 酶或三磷酸腺苷，对所有描述的泛素化事件都是必不可少的。此外，这些小说 泛素操控效应器是最大限度的细胞内细菌复制所必需的，这是不同的 与军团菌IV型效应器的大部分有明显的相关性。通过生化和结构分析，我们将首先 研究这些蛋白质的作用机制。我们还将通过以下方式研究对它们活动的监管 来自细菌的因子并确定这种活性如何有助于吞噬小体的生物发生 支持细胞内细菌复制。这些研究不仅将揭示寄主的新机制 细胞内病原体的功能开发，但也将有可能修改目前的 了解泛素化，这是一种非常重要的信号机制。

Project Summary Active modulation of host function is essential for the success of bacterial pathogens. The ubiquitin network regulates virtually every cellular process in eukaryote, particularly those involved in the detection, recognition and response to infection. It is thus not unexpected that many pathogens target host ubiquitination for their benefits. Earlier studies revealed that Legionella pneumophila, the causative agent of Legionnaires' disease, interferes with host ubiquitin signaling by using at least 9 of its Dot/Icm effectors. Our recent study has identified members of the SidE effector family as unique ubiquitin manipulation enzymes. First, these proteins contain a deubiquitinase motif that attacks ubiquitinated proteins. Second, these proteins catalyze ubiquitination by an unusual mechanism: the reaction does not require the E1, E2 enzymes or ATP, factor that are essential for all described ubiquitination events. Furthermore, these novel ubiquitin manipulating effectors are required for maximal intracellular bacterial replication, which differs sharply with the majority of Legionella type IV effectors. By biochemical and structural analyses, we will first study the mechanisms of action of these proteins. We will also study the regulation of their activity by factors from the bacterium and determine how such activity contributes to the biogenesis of the phagosome supportive of intracellular bacterial replication. These studies will not only reveal novel mechanisms of host function exploitation by intracellular pathogens, but also will have the potential to revise the current understanding of ubiquitination, an enormously important signaling mechanism.