Modulation of Host Cell Functions by Coxiella burnetii

描述（由申请人提供）：伯纳氏杆菌是一种专性细胞内病原体，生长在与溶酶体融合产生的特殊液泡内。参与这种独特的区室的产生和调节宿主细胞功能的克希氏菌蛋白是未知的。有研究认为，coxiella编码型IVB蛋白分泌系统参与了宿主的发病机制。科希氏菌型IVB系统在功能上与胞内致病菌嗜肺军团菌中的Dot/lcm系统相关。这两种IV型细菌分泌系统之间的相似性已被用于鉴定通过军团菌Dot/lcm系统转运到真核宿主细胞中的科希氏菌蛋白。作为Dot/lcm系统底物的Coxiella蛋白都含有多个锚蛋白重复结构域，这些结构域是许多真核蛋白中发现的蛋白-蛋白相互作用结构域。待验证的假设是，这些Coxiella Ank蛋白是在Coxiella感染期间转运到宿主细胞中的Dot/lcm底物，并且这些Ank蛋白直接参与宿主细胞功能的调节。检测Ank蛋白在感染Coxiella的细胞中的定位将检测这些蛋白是否易位。真核宿主细胞中Ank蛋白的异位产生将揭示受Ank蛋白影响的宿主过程。将确定Ank蛋白的细胞靶点，并使用遗传和分子方法鉴定Coxiella Dot/lcm系统的其他底物。这些研究将阐明允许宿主细胞感染克希氏菌的致病决定因素，并揭示这种重要病原体采用的细胞内感染策略。

DESCRIPTION (provided by applicant): Coxiella burnetii is an obligate intracellular pathogen that grows within a specialized vacuole that is derived from fusion with lysosomes. Coxiella proteins that participate in the creation of this unique compartment and that modulate host cell functions are unknown. It has been proposed that a Coxiella-encoded type IVB protein secretion system is involved in host pathogenesis. The Coxiella type IVB system is functionally related to the Dot/lcm system found in the intracellular pathogen Legionella pneumophila. The similarity between these two bacterial type IV secretion systems has been exploited to identify Coxiella proteins that are translocated into eukaryotic host cells by the Legionella Dot/lcm system. The Coxiella proteins identified as substrates of the Dot/lcm system all contain multiple ankyrin-repeat domains, which are protein-protein interaction domains found in many eukaryotic proteins. The hypothesis to be tested is that these Coxiella Ank proteins are Dot/lcm substrates translocated into host cells during Coxiella infection and that these Ank proteins are directly involved in modulation of host cell functions. Examining the localization Ank proteins in cells infected with Coxiella will test whether these proteins are translocated. Ectopic production of Ank proteins in eukaryotic host cells will reveal host processes that are affected by Ank proteins. Cellular targets for the Ank proteins will be determined and additional substrates of the Coxiella Dot/lcm system will be identified using genetic and molecular approaches. These studies will elucidate pathogenic determinants that allow host cell infection by Coxiella and reveal intracellular infection strategies employed by this important pathogen.