Isolation and Characterization of Pseudomonas Type III Effectors That Suppress Programmed Cell Death in Eukaryotes

假单胞菌是一种病原体，其与植物的相互作用可以采取两种截然不同的过程。在与敏感植物的毒性相互作用中，细菌引起疾病，而在与抗性植物的无毒相互作用中，细菌触发快速的防御相关程序性细胞死亡（PCD），称为过敏反应（HR）。这两种结果都是由细菌蛋白质通过一种称为III型分泌系统（TTSS）的蛋白质递送系统注入植物细胞来控制的。该项目的初步数据显示，几种细菌蛋白质作为HR的抑制因子。值得注意的是，这些PCD抑制因子还具有抑制酵母细胞凋亡（在动物中发现的一种PCD）的功能，并抑制小鼠促凋亡蛋白Bax诱导植物和酵母细胞凋亡的能力。这表明这些蛋白质以跨界方式作为抗凋亡因子发挥作用。该项目将使用酵母和植物系统中的筛选来分离作为PCD抑制剂的其他细菌蛋白。此外，该项目将描述每种抑制因子，以确定它们对植物防御的其他标志的一般影响。本项目中描述的实验为学生提供了广泛的培训。除了微生物学，植物生物学和功能基因组学的当前方法外，所追求的主题对哺乳动物系统具有重要影响，大大增加了该研究计划的广度。研究人员参与了UNL内布拉斯加州青年科学家（YNS）计划的建立，该计划旨在加强对生命科学感兴趣的少数民族高中生的招聘。该计划是不寻常的，因为它提供了导师的学生从高中到他们的本科生涯。此外，研究人员还与内布拉斯加州卫斯理大学（Nebraska Wesleyan University）展开了合作，这是一所优秀的文科大学。因此，研究小组将增加其本科生的数量，其中许多来自代表性不足的族裔群体。

Pseudomonas syringae is a pathogen whose interactions with plants can take two strikingly different courses. In virulent interactions with susceptible plants, bacteria cause disease, whereas in avirulent interactions with resistant plants, bacteria trigger a rapid, defense-associated programmed cell death (PCD) known as the hypersensitive response (HR). Both outcomes are controlled by bacterial proteins injected into plant cells by a protein delivery system called the type III secretion system (TTSS). Preliminary data on this project show that several bacterial proteins act as suppressors of the HR. Remarkably, these PCD suppressors also function to inhibit yeast apoptosis (a type of PCD found in animals) and inhibit the ability of the mouse pro-apoptotic protein, Bax, to induce apoptosis in plants and yeast. This indicates that these proteins function as anti-apoptotic factors in a trans-kingdom manner. This project will use screens in yeast and plant systems to isolate additional bacterial proteins that act as PCD suppressors. Moreover, the project will characterize each suppressor to determine their general effect on other hallmarks of plant defense. The experiments described in this project offer broad training for students. Besides current approaches in microbiology, plant biology, and functional genomics, the topics pursued have important ramifications for mammalian systems, greatly adding to the breadth of this research program. The researchers have participated with the establishment of the UNL Young Nebraska Scientist (YNS) program, designed to enhance the recruitment of minority high school students who have demonstrated interest in the life sciences. The program is unusual in that it provides mentorship to the student from high school through their undergraduate career. Also, the researchers have initiated collaboration with Nebraska Wesleyan University, an excellent liberal arts college. Thus, the research group will enhance its pool of undergraduates, many of which are from under-represented ethnic groups.