Elucidating the Biogenesis of the Yersinia pestis Containing Vacuole

 描述(申请人提供)：鼠疫耶尔森氏菌是一种兼性细胞内病原体，可引起鼠疫。越来越多的证据表明，巨噬细胞内的生长对鼠疫杆菌的毒力是重要的。在吞噬时，鼠疫杆菌改变吞噬小体的成熟，在细胞内产生一个保护性的隔间，称为含有耶尔森氏菌的空泡(YCV)。YCV产生的关键步骤包括抑制YCV的酸化，扩展到一个宽敞的液泡中，以及获得自噬标记。然而，细菌用来颠覆正常的吞噬小体成熟过程并产生YCV的机制还没有确定。最近，我们已经确定了宿主Rab GTP酶的一个子集，这是鼠疫杆菌在巨噬细胞内生存所必需的。由于Rab蛋白是囊泡运输、吞噬小体成熟和自噬的关键介质，我们推测这些GTP酶是鼠疫杆菌颠覆吞噬小体成熟并产生YCV所必需的，从而保护细菌免受巨噬细胞清除。由于Rab蛋白通过与特定细胞器的直接相互作用和效应蛋白的招募来介导囊泡运输的许多方面，在目标1中，我们将确定鼠疫杆菌细胞内生存所需的Rab GTP酶是否被特异性招募到YCV中。在目标2中，我们将确定单个Rab蛋白在YCV生物发生中的贡献。这些研究将首次确定宿主Rab GTP酶对YCV形成的贡献。最终，了解YCV的生物发生过程将使我们能够识别有助于细胞内生存的鼠疫杆菌致病因子。

 DESCRIPTION (provided by applicant): Yersinia pestis is a facultative intracellular pathogen that causes the disease known as plague. Growing evidence indicates that intracellular growth in macrophages is important for Y. pestis virulence. Upon phagocytosis, Y. pestis alters the maturation of the phagosome to generate a protective compartment within the cell known as the Yersinia containing vacuole (YCV). Key steps in the generation of the YCV include inhibition of YCV acidification, expansion into a spacious vacuole, and acquisition of the autophagic markers. However, the mechanisms used by the bacterium to subvert the normal phagosome maturation process and generate the YCV have not been defined. Recently we have identified a subset of host Rab GTPases that are required for Y. pestis to survive within macrophages. Because Rab proteins are key mediators of vesicular trafficking, phagosome maturation, and autophagy, we hypothesize that these GTPases are required by Y. pestis to subvert phagosome maturation and generate the YCV, thus protecting the bacterium from macrophage clearance. As Rab proteins mediate many aspects of vesicular trafficking through direct interactions with specific organelles and recruitment of effector proteins, in Aim 1 we will determine if Rab GTPase required for Y. pestis intracellular survival are specifically recruited to the YCV. In Aim 2, we will determine the contribution of individual Rab proteins on the biogenesis of the YCV. These studies will be the first to define the contribution of host Rab GTPases to the formation of the YCV. Ultimately, understanding the YCV biogenesis process will enable us to identify Y. pestis pathogenicity factors that contribute to intracellular survival.