Structural basis for repressor-activator transitions in response to the plant defense hormone, jasmonic acid

当植物受到昆虫取食的伤害或被微生物病原体感染时，它们的反应是产生激素，这些激素起到信号的作用，允许植物进行防御。通常，防御措施包括打开或激活有益基因，帮助植物在损害中幸存下来，然后一旦危险减弱，就关闭或抑制这些基因。这项研究试图了解这些基因如何从“关闭”转变为“开启”的分子细节。对详细机制的了解可能对农业具有广泛的重要意义，因为它为遗传操作和开发优化防御和生长的作物奠定了基础。该项目将为来自当地社区大学的来宾国际研究生和本科生提供研究培训机会，从而为未来科学劳动力的准备做出贡献。此外，通过参与实践研究经验，高中教师将提高他们交流科学过程的能力，并让他们的学生参与到有意义的科学学习中。本研究以植物防御激素茉莉酸为研究对象。在健康的植物中，茉莉酸反应基因被一个多蛋白质复合体结合在一起，该复合体由一种名为Jaz的抑制因子、一种名为MYC的转录激活因子和一组其他蛋白质组成。在没有茉莉酸的情况下，Jaz抑制子抑制MYC激活子，基因转录沉默或关闭。为了应对食草性昆虫和许多微生物病原体的破坏，茉莉酸被产生，并通过诱导JaZ抑制子的蛋白酶体降解来激活这些基因，从而解除对MYC的抑制，MYC通过激活转录来激活基因。参与这种从抑制状态到活性状态转变的许多蛋白质的分子细节和所扮演的角色在很大程度上是未知的。这个项目试图发现参与茉莉酸信号转导的大型多蛋白复合体是如何组装和调节的。方法将包括X射线结晶学、电子显微镜、生化、生物物理和植物分析以及细胞信号重建的组合。由于许多信号级联导致从抑制基因表达到活跃基因表达的转变，因此这一结果可以作为发现并最终操纵负责调控的蛋白质复合体的范例。该奖项是由生物科学局分子生物科学部的遗传机制和分子生物物理学项目共同资助的。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

When plants are wounded by insect feeding or infected by microbial pathogens, they respond by producing hormones that function as signals to allow the plant to mount a defense. Often the defense involves turning on, or activating, beneficial genes that help the plant survive the damage and then turning off, or repressing, those genes once the danger wanes. This research seeks to understand the molecular details of how these genes transition from "off" to "on". Knowledge of the detailed mechanism could be broadly important for agriculture by providing a foundation for genetic manipulation and development of crop plants optimized for defense and growth. This project will offer research training opportunities to guest international graduate students and undergraduates from from a local community college, thereby contributing to the preparation of the future scientific workforce. In addition, through participation in hands-on research experiences, high school teachers will improve their ability to communicate the scientific process and engage their students in meaningful science learning. This research is focused on the plant defense hormone jasmonate. In healthy plants, jasmonate-responsive genes are bound by a multi-protein complex composed of a repressor called JAZ, a transcriptional activator called MYC, and a group of other proteins. In the absence of jasmonate, the JAZ repressor inhibits the MYC activator, and the genes are transcriptionally silent, or off. In response to damage from herbivorous insects and many microbial pathogens, jasmonate is produced and turns on these genes by inducing the proteasomal degradation of the JAZ repressor, thereby relieving inhibition of MYC, which turns on the genes by activating transcription. The molecular details and the roles played by the many proteins that participate in this transition from repressed to active state are largely unknown. This project seeks to discover how the large multi-protein complexes involved in jasmonate signaling are assembled and regulated. Approaches will include a combination of X-ray crystallography, electron microscopy, biochemical, biophysical, and in planta analyses, and in cell signaling reconstitution. Because many signaling cascades result in transitions from repressed to active gene expression, the results could serve as a paradigm for discovering, and eventually manipulating, the responsible regulatory protein complexes. This award was co-funded by the Genetic Mechanisms and the Molecular Biophysics Programs in the Division of Molecular Biosciences in the Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.