The Effect of the Pseudomonas Syringae Protein HopPsyA (HrmA) on Plants

迄今为止，研究细菌植物病原体III型（Hrp）蛋白分泌系统的蛋白质的研究人员还不知道这些蛋白质的任何毒力靶点——细菌预期的靶点可能有助于这些细菌的致病性。本提案中描述的实验旨在揭示HopPsyA（正式称为HrmA）的毒力靶点。HopPsyA是一种通过植物病原体丁香假单胞菌III型（Hrp）分泌途径传播的蛋白质，根据间接证据，似乎可以被传递到植物细胞中。在一些植物上，HopPsyA作为一种无毒蛋白（Avr）起作用，并诱导快速防御反应。通过建立防御反应来关注不识别HopPsyA的植物，研究人员希望确定HopPsyA的植物靶标，从而开始揭示酶传递蛋白如何允许致病菌繁殖并导致植物疾病。本文提出的酵母2杂交数据表明，HopPsyA靶向拟南芥中的Mad2蛋白。Mad2是真核生物中的一种保守蛋白，在细胞周期中起重要作用。当真核细胞在中期纺锤体受损时，一个叫做纺锤体检查点的检查点会阻止细胞周期，使细胞不能继续进入后期。这有助于防止子细胞在分离过程中接受过多或过少的染色体。Mad2在纺锤体检查点中起核心作用。有趣的是，如果HopPsyA确实与Mad2相互作用，这表明细菌植物病原体可能能够改变植物细胞周期，以提高成功发病的可能性。拟议的工作将包括许多不同的分子和细胞生物学技术，包括标准光学显微镜，酵母2杂交筛选，PCR诱变，蛋白质分离和免疫印迹分析，转基因植物实验，共免疫沉淀和其他方法来检测蛋白质-蛋白质相互作用。动物和植物病原体中III型系统之间的许多成分是保守的。本提案中描述的研究应提供有关III型分泌系统的重要信息，并对研究宿主-微生物相互作用的研究人员具有广泛的兴趣。

To date, researchers studying proteins that travel the type III (Hrp) protein secretion system of bacterial plant pathogens do not know any of the virulence targets of these proteins - the bacterial-intended target that presumably contributes to the ability of these bacteria to be pathogenic. The experiments described in this proposal are designed to reveal the virulence target of HopPsyA (formally known as HrmA). HopPsyA is a protein that travels the type III (Hrp) secretion pathway of the plant pathogen Pseudomonas syringae and, based on indirect evidence, appears to be delivered into plant cells. On some plants, HopPsyA functions as an avirulence (Avr) protein and induces a rapid defense response. By focussing on plants that do not recognize HopPsyA by mounting a defense response, the researchers hope to identify HopPsyA's plant target to begin to unravel how Hrp-delivered proteins allow pathogenic bacteria to multiply and cause disease in plants. Yeast 2-hybrid data presented in this proposal suggest that HopPsyA targets the Mad2 protein in Arabidopsis. Mad2 is a conserved protein in eucaryotes that plays an important role in the cell cycle. When eucaryotic cells have damaged spindles during metaphase, a checkpoint, called the spindle checkpoint, stalls the cell cycle so the cells do not continue into anaphase. This helps prevent daughter cells from receiving too many or too few chromosomes during segregation. Mad2 plays a central role in the spindle checkpoint. Intriguingly, if HopPsyA does indeed interact with Mad2, this suggests that bacterial plant pathogens may be capable of modifying the plant cell cycle to improve the likelihood of successful pathogenesis. The proposed work will encompass many different molecular and cell biological techniques including standard light microscopy, yeast 2-hybrid screens, PCR mutagenesis, protein separation and immunoblot analysis, experiments with transgenic plants, coimmunoprecipitation and other methods to detect protein-protein interactions. Many components between the type III systems in pathogens of animal and plants are conserved. The research described in this proposal should provide important information about type III secretion systems and be of broad interest to researchers studying host-microbe interactions.