Regulation of defense signaling in tomato

描述（申请人提供）：植物激素茉莉酸（JA）控制宿主免疫和发育的各个方面。对模式植物拟南芥和番茄的研究表明，E3泛素连接酶SCFCOI 1是茉莉酸响应基因转录的严格要求。JAZ（JAs monate ZIM-结构域）蛋白通过与碱性螺旋-环-螺旋转录因子MYC 2相互作用来抑制茉莉酸响应基因的表达。响应于茉莉酸信号，JAZ蛋白受到SCFCOI 1介导的泛素化和随后的26 S蛋白酶体降解。JAZ阻遏物与F-box蛋白COI 1的结合受JA-氨基酸缀合物茉莉酸-异亮氨酸（JA-Ile）刺激。冠菌素是一种由植物病原体产生的毒素，强烈促进COI 1-JAZ相互作用。拟议的研究将使用拟南芥和番茄作为实验模型系统，以发展COI 1是JA-Ile和冠菌素受体的假设，以及JAZ阻遏蛋白决定SCFCOI 1控制茉莉酸调节过程多样性的特异性。生物化学、遗传学和细胞生物学方法的组合将用于解决以下具体目标：1）确定COI 1和JAZ在结合茉莉酸配体中的作用; 2）测量健康、受伤和患病组织中JA-Ile和其他JA-氨基酸缀合物的内源水平; 3）确定JAZ家族成员的生理功能; 4）鉴定JAZ阻遏物的C末端结构域中与COI 1和MYC 2相互作用的区域; 5）确定JAZ-JAZ二聚化在调节茉莉酸反应中的作用。这项研究将有助于广泛了解脂质衍生激素控制多细胞生物体发育和免疫功能的分子机制。茉莉酸信号级联的组分的交叉保守性表明，该研究将提供对植物和动物之间保守的信号过程的深入了解。从植物激素研究中出现的配体介导的SCF-底物识别的范例建立了一种用于在生物系统中感测小分子的新机制，这可能对医学和人类健康具有深远的影响，包括开发靶向人类E3泛素连接酶的药物的潜在新途径。最近发现茉莉酸酯作为抗癌剂进一步表明，拟议的研究与发现针对肿瘤疾病的新型治疗药物有关。最后，这项工作将揭示致病微生物在疾病期间在其真核宿主中选择信号通路的分子机制。关于茉莉酸信号传导机制的拟议研究将广泛有助于了解脂质衍生激素如何控制从植物到人类的多种多细胞生物的发育和免疫功能。E3泛素连接酶对配体介导的靶底物识别的研究将为小分子如何介导生物系统中的蛋白质-蛋白质相互作用提供新的信息，这可能对医学和人类健康产生深远的影响，包括开发靶向人类E3泛素连接酶的药物的潜在新途径。公共卫生相关性：该研究将揭示致病微生物在疾病期间在其真核宿主中选择信号通路的分子机制，并且也与发现新的肿瘤疾病治疗药物有关。

DESCRIPTION (provided by applicant): The plant hormone jasmonic acid (JA) controls diverse aspects of host immunity and development. Studies with the model plant Arabidopsis thaliana and tomato (Solanum lycopersicum) indicate that the E3 ubiquitin ligase SCFCOI1 is strictly required for transcription of jasmonate-responsive genes. JAZ (JAsmonate ZIM-domain) proteins repress the expression of jasmonate-responsive genes by interacting with the basic helix-loop-helix transcription factor MYC2. In response to a jasmonate signal, JAZ proteins are subject to SCFCOI1-mediated ubiquitination and subsequent degradation by the 26S proteasome. Binding of JAZ repressors to the F-box protein COI1 is stimulated by the JA-amino acid conjugate jasmonoyl-isoleucine (JA-Ile). Coronatine, a toxin produced by plant disease-causing pathogens, strongly promotes COI1-JAZ interactions. The proposed research will use Arabidopsis and tomato as experimental model systems to develop the hypotheses that COI1 is a receptor for JA-Ile and coronatine, and that JAZ repressor proteins determine the specificity by which SCFCOI1 controls the diversity of jasmonate-regulated processes. A combination of biochemical, genetic, and cell biological approaches will be used to address the following specific aims: 1) To determine the role of COI1 and JAZ in binding jasmonate ligands; 2) To measure the endogenous level of JA-Ile and other JA-amino acid conjugates in healthy, wounded, and diseased tissues; 3) To determine the physiological function of JAZ family members; 4) To identify regions in the Cterminal domain of JAZ repressors that interact with COI1 and MYC2; and, 5) To determine the role of JAZ-JAZ dimerization in regulating jasmonate responses. This research will contribute broadly to an understanding of the molecular mechanisms by which lipid-derived hormones control developmental and immune function in multicellular organisms. Crosskingdom conservation of components of the jasmonate signaling cascade indicates that the research will provide insight into signaling processes that are conserved between plants and animals. The paradigm of ligand-mediated SCF-substrate recognition that has emerged from plant hormone research establishes a novel mechanism for sensing small molecules in biological systems, which may have far-reaching implications for medicine and human health, including potential new avenues for developing drugs that target E3 ubiquitin ligases in humans. The recent discovery of jasmonates as anti-cancer agents indicates further that the proposed research is relevant to the discovery of novel therapeutic agents against neoplastic disease. Finally, the work will reveal the molecular mechanism by which a pathogenic microbe co-opts signaling pathways in its eukaryotic host during disease. The proposed research on the mechanism of jasmonate signaling will contribute broadly to an understanding of how lipid-derived hormones control developmental and immune function in diverse multicellular organisms, ranging from plants to humans. The study of ligand-mediated recognition of target substrates by E3 ubiquitin ligases will provide new information on how small molecules mediate proteinprotein interactions in biological systems, which may have far-reaching implications for medicine and human health, including potential new avenues for developing drugs that target E3 ubiquitin ligases in humans. PUBLIC HEALTH RELEVANCE: The proposed research will reveal the molecular mechanism by which a pathogenic microbe coopts signaling pathways in its eukaryotic host during disease, and is also relevant to the discovery of novel therapeutic agents against neoplastic disease.