Structural and functional analyses of a bacterial protein translocation domain that has adopted diverse pathogenic effector functions within host cells

病原菌的成功感染策略通常依赖于细菌效应蛋白易位到受感染的宿主细胞中，所述受感染的宿主细胞靶向专用宿主细胞功能以有益于病原体。巴尔通体是兼性胞内病原体，感染包括人在内的多种哺乳动物宿主。为了逃避其宿主的免疫应答，这些“隐形”病原体利用IV型分泌系统将巴尔通体效应蛋白（Beps）的混合物转移到受感染的宿主细胞中。对于Bep分泌到宿主细胞中至关重要的是Bep细胞内递送（BID）结构域，其已在特定情况下进一步显示调节多种宿主细胞过程。因此，BID结构域是第一个已知的具有额外效应子功能的蛋白质分泌信号结构域的例子。然而，BID结构域对Bep易位和效应子功能的相应结构要求尚不清楚。本研究项目的目的是阐明BID结构域在1）效应子易位和2）调节宿主细胞过程中的双重作用。本项目将重点研究Bep转运到宿主细胞和调节宿主细胞过程中所涉及的BID-靶标相互作用的结构和功能。为了理解这些过程，将使用细菌遗传学、蛋白质易位和生理测定、生物物理方法和结构分析的组合。该奖学金将包括对有经验的研究人员进行先进技术的培训，这将导致他的科学独立性。该项目的结果将是重要的分子微生物学和感染生物学领域，并将有助于更好地了解细菌效应易位和功能的分子。

The successful infection strategy of pathogenic bacteria often relies on the translocation of bacterial effector proteins into infected host cells that target dedicated host cellular functions to the benefit of the pathogen. Bartonella spp. are facultative intracellular pathogens that infect a wide range of mammalian hosts including humans. In order to escape the immune response of their hosts these “stealth” pathogens utilize a type IV secretion system to translocate a cocktail of Bartonella effector proteins (Beps) into infected host cells. Crucial for Bep secretion into host cells is the Bep intracellular delivery (BID) domain, that has been further shown in specific cases to modulate diverse host cellular processes. Thus, the BID domain is the first known example of a protein secretion signal domain that has adopted additional effector functions. However, the respective structural requirements of the BID domain for Bep-translocation and effector function are not understood. The objective of this research project is to elucidate the dual role of the BID domain in 1) effector translocation and 2) modulation of host cellular processes. This project will focus on the structural and functional elucidation of BID-target interactions involved in Bep-translocation into host cells and modulation of host cellular processes. In order to understand these processes, a combination of bacterial genetics, protein translocation and physiological assays, biophysical methods and structural analyses will be used. The fellowship will include training of the experienced researcher in advanced techniques that will lead to his scientific independency. Results of this project will be important for the fields of molecular microbiology and infection biology and will contribute to a better molecular understanding of bacterial effector translocation and function.