Effector Recognition and Molecular Activation of an Arabidopsis NLR Immune Receptor Specifying Disease Resistance to Hyaloperonospora arabidopsidis

植物面临病原微生物的持续攻击，并依靠复杂的免疫系统来抵御它们。这种免疫系统的核心是细胞内的抗性蛋白，这些蛋白识别微生物衍生的效应蛋白，并在植物细胞中诱导生理变化，最终导致局部细胞死亡和遏制入侵的病原体。本项目的目的是在拟南芥/霜霉病模型系统中更详细地研究这样的抗性蛋白/效应器对RPP1/ATR1，并更好地了解参与效应器识别和抗性蛋白激活的分子事件。研究人员将使用遗传和生化方法来获得RPP1和ATR1之间直接相互作用的确凿证据。分离抗性蛋白的纯蛋白提取物一直是一项具有挑战性的工作，因此研究人员将在Planta表达系统中通过共结晶和蛋白质下拉实验获得足够的RPP1蛋白，以进行与ATR1的直接相互作用研究。抗性蛋白和效应蛋白的随机突变将提供对这些蛋白相互作用至关重要的氨基酸残基的详尽图谱。在免疫应答过程中，抗性蛋白的精确计时和定位是必不可少的。RPP1包含将蛋白质靶向细胞核和/或膜的信号序列。在这个项目中，研究人员将确定突变这些信号序列对RPP1介导的抗性的影响。最后，在识别效应器之前和之后，将使用生化方法来研究抗性蛋白的激活，以识别与RPP1相关的蛋白。综上所述，该项目的结果将增强我们对植物抗病信号的基本理解，最终可能转化为农业研究，并产生更可持续的作物保护方法。该项目将为博士后和博士后研究员以及本科生提供培训。

Plants face continuous attacks by pathogenic microbes and rely on a sophisticated immune system to ward them off. Central to this immune system are intracellular resistance proteins that recognize microbe-derived effector proteins and induce physiological changes in the plant cell that ultimately lead to localized cell death and containment of the invading pathogen. This project aims at investigating in more detail one such resistance protein/effector pair RPP1/ATR1 in the model system Arabidopsis/downy mildew and to gain a better understanding of the molecular events involved in effector recognition and resistance protein activation. The investigators will use genetic and biochemical approaches to obtain definitive evidence for direct interaction between RPP1 and ATR1. Isolation of pure protein extracts of resistance proteins has been challenging, thus the investigators will employ in planta expression systems to obtain enough RPP1 protein to perform direct interaction studies with ATR1 through co-crystallization and protein pull-down experiments. Random mutagenesis of both resistance and effector proteins will provide an exhaustive map of amino acid residues that are crucial for the interaction of these proteins. Precise timing and localization of resistance proteins is imperative during an immune response. RPP1 contains signal sequences that target the protein to the nucleus and/or membrane. In this project the investigators will determine the effect of mutating these signal sequences on RPP1-mediated resistance. Finally, resistance protein activation will be studied using biochemical approaches to identify proteins associating with RPP1 prior to and upon effector recognition. Taken together, results from this project will enhance our basic understanding of plant disease resistance signaling, which may ultimately be translated into agricultural research and result in more sustainable approaches of crop protection. The project will provide training for pre- and post-doctoral fellows as well as undergraduate students.