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

植物面临着病原微生物的持续攻击，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抗性蛋白，它识别微生物衍生的效应蛋白，并诱导植物细胞的生理变化，最终导致局部细胞死亡和入侵病原体的遏制。本项目旨在对拟南芥/霜霉病模型系统中一个这样的抗性蛋白/效应蛋白对RPP1/ATR1进行更详细的研究，以更好地了解效应蛋白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明确证据。抗性蛋白的纯蛋白提取物的分离一直具有挑战性，因此研究人员将在植物表达系统中通过共结晶和蛋白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诱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，精确的定时和定位抗性蛋白是必不可少的。RPP1含有将蛋白靶向到细胞核和/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，抗性蛋白激活将使用生化方法进行研究，以确定在效应物识别之前和之后与RPP1相关的蛋白质。总的来说，这个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。该项目将为博士生和博士后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.