Analysis of an orchestrated cell death mediated by Vibrio parahaemolytics T3SS1

描述（由申请人提供）：本申请的最终目标是确定革兰氏阴性菌副溶血性弧菌III型分泌系统1 （T3SS1）靶向的宿主信号通路；与食用受污染的海鲜有关的肠胃炎爆发的主要病原体。环境中副溶血性弧菌的流行和感染发生率与全球变暖导致的水温上升有关。T3SS是一种针状结构，可以有效地将细菌的毒力因子转移到宿主细胞的细胞质中。毒力因子（也称为细菌效应物）以与许多病毒致癌基因相似的方式进化；真核生物的活性被病原体篡夺和修饰，以获得自身的优势。副溶血性弧菌的基因组测序显示存在两个致病岛，它们同时编码T3SS和推测的效应物。第一个致病性岛含有T3SS1并与细胞毒性有关，而第二个致病性岛含有T3SS2并与肠毒性有关。第一致病性岛上的效应物被鉴定为开放阅读框，与任何已知蛋白没有明显的同源性。最近，我们已经证明了副溶血性弧菌利用T3SS1通过诱导自噬、细胞围合和细胞裂解来协调宿主细胞的多方面感染。我们已经展示了T3SS1效应物之一，VopS，利用一种称为ampyation的新型翻译后修饰来破坏宿主信号传导。在此，我们提出了特异性目的，通过鉴定三种已知效应物的活性和宿主靶点，鉴定T3SS1分泌的其他效应物，并表征感染过程中被副溶血性弧菌破坏的宿主信号通路，研究T3SS1诱导的多方面死亡。这些研究为这种有害的胃肠道细菌病原体副溶血性弧菌的分子机制提供了分子视角。

DESCRIPTION (provided by applicant): The ultimate goal of this application is to identify the host signaling pathways targeted by the type III secretion system 1 (T3SS1) of the gram-negative bacterium Vibrio parahaemolyticus; a major agent responsible for gastroenteritis outbreaks associated with the consumption of contaminated seafood. The prevalence of V. parahaemolyticus in the environment and incidence of infection have been linked to rising water temperatures caused by global warming. A T3SS is a needle-like structure that efficiently translocates virulence factors from bacteria into the cytosol of a host cell. The virulence factors (also called bacterial effectors) have evolved in a manner similar to many of the viral oncogenes; a eukaryotic activity is usurped and modified by the pathogen for its own advantage. Genomic sequencing of V. parahaemolyticus revealed the existence of two pathogenicity islands that encode both a T3SS and putative effectors. The first pathogenicity island contains T3SS1 and is associated with a cytotoxicity, while the second pathogenicity island contains T3SS2 and is associated with an enterotoxicity. The effectors on the first pathogenicity island have been identified as open reading frames with no obvious homology to any known protein. Recently, we have demonstrated that the V. parahaemolyticus uses T3SS1 to orchestrate a multifaceted host cell infection by induction of autophagy, cell rounding and then cell lysis. We have shown one of the T3SS1 effectors, VopS, utilizes a novel posttranslational modification called AMPylation to disrupt host signaling. Herein, we propose Specific Aims to study the multifaceted death induced by T3SS1 by identifying the activity and host targets of three known effectors, identify other effectors secreted by T3SS1 and characterize the host signaling pathways that are disrupted by V. parahaemolyticus during infection. These studies provide molecular insight into the molecular mechanisms used by this harmful gastrointestinal bacterial pathogen V. parahaemolyticus. PUBLIC HEALTH RELEVANCE: The gram-negative bacterium Vibrio parahaemolyticus is a major agent responsible for gastroenteritis outbreaks associated with the consumption of contaminated seafood. The prevalence of V. parahaemolyticus in the environment and incidence of infection have been linked to rising water temperatures caused by global warming. Genomic sequencing of the marine bacterium V. parahaemolyticus revealed the existence of two pathogenicity islands that encode both a type III secretion system (T3SS) and putative effectors. Herein, we propose Specific Aims to study the multifaceted death induced by T3SS1 by identifying the activity and host targets of three known effectors, identify other effectors secreted by T3SS1 and characterize the host signaling pathways that are disrupted by V. parahaemolyticus during infection.