Modulation of Host Vesicle Trafficking by Legionella pneumophila

描述(申请人提供)：嗜肺军团菌，军团病的病原体是一种细胞内的病原体。致病的关键是Dot/ICM IV型分泌系统，它将大量的细菌效应物转移到宿主细胞中。这些效应器调节多个宿主细胞的过程，以创建内质网(ER)来源的细胞器，允许军团菌在细胞内生长。我们最近发现SidJ在复制型军团菌空泡(LCV)的生物发生中起着重要作用，SidJ的缺失会导致ER蛋白募集到LCV的时间延迟。进一步的研究表明，SidJ是一种蛋白磷酸酶，它与COPII包裹的囊泡外壳复合体的主要亚单位Sec31相互作用并使其去磷酸化。我们的工作假设是，SidJ通过与其他效应器的协调，将包裹COPII的囊泡的运输重新定向到细菌吞噬小体。本项目的目标是利用遗传学、生物化学和细胞生物学方法研究军团菌感染过程中SidJ及其蛋白磷酸酶的活性。我们建议：1)分析SidJ与Sec31的相互作用以及SidJ对宿主分泌途径的影响。2)研究SidJ-Sec31相互作用在COPII包被囊泡形成中的作用。3)识别和表征与SidJ协同作用的效应器。这项研究的结果将有助于新兴的细胞微生物学领域和细胞生物学领域，特别是COPII组分的蛋白磷酸化在囊泡运输调节中的作用。这些研究还将扩大我们的研究能力，从而使我们能够建立一个具有更广泛项目范围的研究计划。K02奖将使我能够投入更多的精力来发展我的研究事业，通过探索和获得这一多学科领域未来成功所必需的背景知识和新技术。 相关性：由于其潜在的致命性，由嗜肺军团菌感染是一个公共卫生问题。我们的研究可以为其预防和/或治疗提供新的策略。此外，了解受这种细菌影响的哺乳动物细胞过程可能会为我们研究与这些过程异常有关的其他疾病提供线索。 项目简介：由嗜肺军团菌感染通常会导致一种致命的肺炎。此外，对这种细菌的研究可以为我们理解其他细胞内病原体提供帮助，因为嗜肺乳杆菌和这些病原体具有许多共同的致病机制。

DESCRIPTION (provided by applicant): Legionella pneumophila, the etiological agent of Legionnaires' disease is an intracellular pathogen. Essential to its pathogenicity is the Dot/Icm type IV secretion system that translocates a large number of bacterial effectors into host cell. These effectors modulate multiple host cell processes to create an endoplasmic reticulum (ER) derived organelle permissive for Legionella intracellular growth. We recently found that one of such effectors called SidJ plays an important role in the biogenesis of replicative Legionella-containing vacuoles (LCVs) and loss of SidJ results in a temporal delay in the recruitment of ER proteins to the LCVs. Further studies indicate that SidJ is a protein phosphatase that interacts with and dephosphorylates Sec31, the major subunit of the outer shell complexes of the COPII-coated vesicles. Our working hypothesis is that SidJ, by coordinating with other effectors, redirects the trafficking of COPII-coated vesicles to the bacterial phagosomes. The goal of this project is to characterize SidJ and its protein phosphatase activity in Legionella infection using genetic, biochemical and cell biological approaches. We propose to: 1) Analyzing the interactions between SidJ and Sec31 and the effect of SidJ on host secretory pathways. 2) Studying the functional consequence of SidJ-Sec31 interaction on COPII coated vesicle formation. 3) Identification and characterization of effectors that function synergistically with SidJ. Results from this study will contribute to the emerging field of cellular microbiology and to the field of cell biology, particularly the roles of protein phosphorylation of COPII components in the regulation of vesicle trafficking. These studies will also expand our research capacity, thus allowing us to establish a research program with a broader spectrum of projects. A K02 award would allow me to invest more effort to develop my research career by exploring and acquiring background knowledge and new techniques necessary for future success in this multidisciplinary field. Relevance: Because of its potential fatality, infection by Legionella pneumophila is a concern of public health. Our study can provide novel strategies for its prevention and/or treatment. Furthermore, understanding of mammalian cell processes affected by this bacterium could lead to clues in our study of other diseases associated with abnormality of these processes. Project Narrative: Infection by Legionella pneumophila often leads to the development of a fatal form of pneumonia. In addition, study on this bacterium could share light on our understanding of other intracellular pathogens because L. pneumophila and these infectious agents share many pathogenic mechanisms.