Modulation of Host Cell Functions by Coxiella burnetii

描述（由申请方提供）：贝氏柯克斯体是一种专性细胞内病原体，在与溶酶体融合产生的特化空泡内生长。参与这种独特区室的形成并调节宿主细胞功能的柯克斯体蛋白是未知的。已经提出，柯克斯体编码的IVB型蛋白分泌系统参与宿主发病机制。Coxiella type IVB系统在功能上与胞内病原体嗜肺军团菌中发现的Dot/lcm系统相关。这两种细菌IV型分泌系统之间的相似性已被利用来鉴定通过军团菌Dot/lcm系统易位到真核宿主细胞中的柯克斯体蛋白。被鉴定为Dot/lcm系统的底物的柯克斯体蛋白都含有多个锚定重复序列结构域，其是在许多真核蛋白中发现的蛋白质-蛋白质相互作用结构域。待测试的假设是这些Coxiella Ank蛋白是在Coxiella感染期间易位到宿主细胞中的Dot/lcm底物，并且这些Ank蛋白直接参与宿主细胞功能的调节。检查被Coxiella感染的细胞中Ank蛋白的定位将测试这些蛋白是否易位。Ank蛋白在真核宿主细胞中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。这些研究将阐明致病的决定因素，使宿主细胞感染柯克斯体，并揭示细胞内感染的策略，这一重要的病原体。

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.