Antimicrobial Plant Defensins:Structure-Activity Relationships and Modes of Action

植物经常受到病原体的攻击，尤其是来自致病性真菌的攻击。作为保护自己免受真菌攻击的各种防御策略的一部分，植物产生被称为防御素的小抗真菌蛋白质。防御素是在植物的正常生长和发育过程中产生的，也是对真菌攻击的反应。其中一些蛋白质是真菌病原体的有效抑制剂。PI和他的研究小组从紫花苜蓿中分离出了两种植物防御素，MsDef1和MtDef4，这两种植物防御素可以抑制稻瘟病菌的生长，稻瘟病菌是一种导致小麦和大麦严重枯萎病的真菌病原体。这些蛋白在转基因植物中的组成表达对真菌的攻击提供了强有力的保护。为了在转基因作物中有效地利用这些蛋白质，需要解决的一个关键问题是了解它们的结构-活性关系、作用模式以及真菌对这些蛋白质产生抗性的机制。初步数据表明，MsDef1和MtDef4具有不同的抗真菌作用模式，且各自独立作用于禾本科F. graminearum。计划中的研究将确定这些蛋白质独特的抗真菌活性所必需的结构特征和活性位点。此外，每种蛋白利用的真菌毒性途径将被阐明。更广泛的影响计划中的研究将阐明抗真菌植物防御素抑制真菌生长的分子机制。这些知识将使这些蛋白质在转基因作物中长期有效地用于真菌病原体的生物控制。这项研究还将有助于为作物和哺乳动物的安全奠定基础，从而为在转基因作物中使用这些蛋白质提供更大的安全感。此外，从计划中的研究中获得的知识将有助于未来发现环境安全的杀菌剂。此外，本项目还为博士后、少数民族本科生和高中生提供培训机会。pi将继续通过丹佛斯中心的现有项目与学生协调并提供研究机会。参与者不仅将学习蛋白质生物化学和工程，还将学习前沿的真菌基因组学和蛋白质组学技术。为了增强更广泛的科学影响，计划在专业会议上发表报告，并在同行评议的期刊上发表文章。

Intellectual Merit Plants constantly encounter pathogen attacks, especially from pathogenic fungi. As part of various defense strategies to protect themselves against fungal attack, plants produce small antifungal proteins known as defensins. Defensins are produced during the normal growth and development of plants and also in response to fungal attack. Some of these proteins are potent inhibitors of fungal pathogens. The PI and his research team have isolated two plant defensins, MsDef1 and MtDef4, from Medicago spp. that inhibit the growth of Fusarium graminearum, a fungal pathogen which causes devastating head blight disease in wheat and barley. The constitutive expression of these proteins in transgenic plants affords strong protection from fungal attack. A critical issue that needs to be addressed for effective use of these proteins in transgenic crops is understanding their structure-activity relationships, modes of action and the mechanisms by which fungal resistance to these proteins might emerge. Preliminary data suggest that MsDef1 and MtDef4 have different modes of antifungal action and act independently on F. graminearum. The planned research will identify the structural features and active sites that are essential for the unique antifungal activity of these proteins. In addition, the fungal toxicity pathway utilized by each protein will be elucidated. Broader ImpactsThe planned research will shed light on the molecular mechanisms by which antifungal plant defensins inhibit the growth of fungi. This knowledge will enable an effective long-term use of these proteins for biological control of fungal pathogens in transgenic crops. The research will also help establish the foundation for crop and mammalian safety, thus providing a greater sense of security about the use of these proteins in transgenic crops. Moreover, knowledge gained from the planned studies will facilitate future discovery of environmentally safe fungicides. In addition, this project provides a training opportunity for a postdoc as well as minority undergraduates and high school students. The PIs will continue to coordinate with and provide research opportunities through existing programs for students at the Danforth Center. Participants will learn not only protein biochemistry and engineering, but also cutting-edge fungal genomics and proteomics technologies. To enhance the wider scientific impact, presentations at professional meetings and publications in peer-reviewed journals are planned.