Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor.
Structural basis of pathogen recognition by an integrated HMA domain in a plant NLR immune receptor.
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DOI：
10.7554/elife.08709
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发表时间：
2015-08-25
期刊：
影响因子：
7.7
通讯作者：
Banfield MJ
中科院分区：
文献类型：
--
作者：
Maqbool A;Saitoh H;Franceschetti M;Stevenson CE;Uemura A;Kanzaki H;Kamoun S;Terauchi R;Banfield MJ
植物已经进化出细胞内免疫受体来检测被称为效应子的病原体蛋白。这些免疫受体如何检测效应器仍然知之甚少。在这里，我们描述了直接识别的AVR-Pik，从稻瘟病病原体的效应，由水稻细胞内NLR免疫受体Pik的结构基础。AVR-PikD以纳摩尔亲和力结合Pikp-1 HMA整合结构域的二聚体。Pikp-HMA/AVR-PikD复合物的晶体结构使得能够设计突变以改变酵母中和体外的蛋白质相互作用，并且在含有Pikp的水稻栽培品种中以及在模型植物本氏烟草中表达AVR-PikD和Pikp时干扰效应子介导的应答。这些数据揭示了一个识别事件的分子细节，介导的一个新的整合域的NLR，启动植物的免疫反应和抗稻瘟病。这些研究为在主食作物中对植物病原体进行工程抗病提供了新的机会。植物病害减少了世界上最重要的粮食作物的收成，包括小麦、水稻、马铃薯和玉米。这些疾病对全球粮食安全和当地自给农业都很重要。为了对抗这些疾病，作物（像所有植物一样）具有免疫系统，可以检测致病微生物（也称为病原体）产生的指示分子，并启动防御反应以保护植物。结合核苷酸的富含亮氨酸的重复受体（简称NLR）是一种植物蛋白，它可以在植物细胞内部寻找这些指示分子。几十年来，这些受体在将抗病性培育到作物中的努力中发挥了核心作用，但人们对它们的工作原理知之甚少。Maqbool，Saitoh等人现在已经使用了一系列生物化学，结构生物学和基于活性的测定来研究来自水稻的一个NLR如何直接与来自稻瘟病真菌的分子相互作用。这种真菌会导致水稻最重要的疾病（称为稻瘟病），这种真菌分子也被称为“效应”蛋白。一种称为X射线晶体学的技术被用来揭示效应器的三维结构，该效应器与称为"整合的HMA结构域"的NLR部分结合。然后使用生物化学技术来测量效应物（和其他相关效应物）与NLR的该结构域相互作用的强度。这些结果，结合对三维结构的仔细检查，允许对效应子进行一系列改变，使其在实验室中停止与NLR蛋白结构域相互作用。Maqbool，Saitoh等人随后在水稻植物中进行了实验，并表明停止其与NLR结构域相互作用的效应子的变化也停止了效应子触发植物中的防御反应。在使用模式植物本塞姆氏烟草（Nicotiana benthamiana）的实验中也获得了类似的结果。世纪中期，美国植物病理学家哈罗德·亨利·弗洛尔提出，植物与致病微生物相互作用的结果是基于特定生物分子之间的相互作用。Maqbool，Saitoh等人的发现为该模型提供了新的结构基础。这些分子相互作用的详细图像将使研究人员能够设计出检测更广泛病原体分子的定制NLR。在未来，这种方法可能有助于保护世界上最重要的作物免受植物病害的影响。DOI：www.example.com网站
Plants have evolved intracellular immune receptors to detect pathogen proteins known as effectors. How these immune receptors detect effectors remains poorly understood. Here we describe the structural basis for direct recognition of AVR-Pik, an effector from the rice blast pathogen, by the rice intracellular NLR immune receptor Pik. AVR-PikD binds a dimer of the Pikp-1 HMA integrated domain with nanomolar affinity. The crystal structure of the Pikp-HMA/AVR-PikD complex enabled design of mutations to alter protein interaction in yeast and in vitro, and perturb effector-mediated response both in a rice cultivar containing Pikp and upon expression of AVR-PikD and Pikp in the model plant Nicotiana benthamiana. These data reveal the molecular details of a recognition event, mediated by a novel integrated domain in an NLR, which initiates a plant immune response and resistance to rice blast disease. Such studies underpin novel opportunities for engineering disease resistance to plant pathogens in staple food crops. DOI: http://dx.doi.org/10.7554/eLife.08709.001 Plant diseases reduce harvests of the world's most important food crops including wheat, rice, potato, and corn. These diseases are important for both global food security and local subsistence farming. To fight these diseases, crops (like all plants) have an immune system that can detect the telltale molecules produced by disease-causing microbes (also known as pathogens) and mount a defence response to protect the plant. Nucleotide-binding, leucine-rich repeat receptors (or NLRs for short) are plant proteins that survey the inside of plant cells looking for these telltale molecules. These receptors have played a central role in efforts to breed disease resistance into crop plants for decades, but little is known about how they work. Maqbool, Saitoh et al. have now used a range of biochemical, structural biology and activity-based assays to study how one NLR from rice directly interacts with a molecule from the rice blast fungus. This fungus causes the most important disease of rice (called rice blast), and the fungal molecule in question is also known as an ‘effector’ protein. A technique called X-ray crystallography was used to reveal the three-dimensional structure of the effector bound to part of the NLR called the ‘integrated HMA domain’. Biochemical techniques were then used to measure how strongly the effector (and other related effectors) interacted with this domain of the NLR. These results, combined with a close examination of the three-dimensional structure, allowed a set of changes to be made to the effector that stopped it interacting with the NLR protein domain in the laboratory. Maqbool, Saitoh et al. then performed experiments in rice plants and showed that changes to the effector that stopped it interacting with the NLR domain also stopped the effector from triggering a defence response in plants. Similar results were also obtained in experiments that used the model plant Nicotiana benthamiana. In the middle of the 20th century, an American plant pathologist called Harold Henry Flor proposed that the outcomes of interactions between plants and disease-causing microbes were based on interactions between specific biological molecules. The findings of Maqbool, Saitoh et al. provide a new structural basis for this model. A detailed picture of these molecular interactions will allow researchers to engineer tailored NLRs that detect a wider range of pathogen molecules. In the future such an approach could contribute to efforts to protect the world's most important crops from plant diseases. DOI: http://dx.doi.org/10.7554/eLife.08709.002