Regulation of defense signaling in tomato

描述（由申请人提供）：植物激素茉莉酸（jasmonic acid， JA）控制宿主免疫和发育的多个方面。对模式植物拟南芥和番茄（Solanum lycopersicum）的研究表明，E3泛素连接酶SCFCOI1是茉莉酸应答基因转录的严格要求。JAZ （JAsmonate ZIM-domain）蛋白通过与基本螺旋-环-螺旋转录因子MYC2相互作用，抑制茉莉酸应答基因的表达。响应茉莉酸信号，JAZ蛋白受到scfco1介导的泛素化和随后的26S蛋白酶体降解。JAZ抑制因子与F-box蛋白COI1的结合是由ja -氨基酸偶联物茉莉异亮氨酸（JA-Ile）刺激的。Coronatine是植物致病菌产生的一种毒素，能强烈促进COI1-JAZ的相互作用。该研究将以拟南芥和番茄为实验模型系统，提出COI1是JA-Ile和冠状碱受体的假设，以及JAZ抑制蛋白决定SCFCOI1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结合将用于解决以下具体目标：1)确定COI1和JAZ在结合茉莉酸配体中的作用；2)测定健康、损伤和病变组织中JA-Ile和其他ja -氨基酸偶联物的内源性水平；3)确定JAZ家族成员的生理功能；4)鉴定与COI1和MYC2相互作用的JAZ阻遏子Cterminal区域；5)确定jazz - jaz二聚化在调节茉莉酸反应中的作用。这项研究将广泛有助于了解脂质衍生激素控制多细胞生物发育和免疫功能的分子机制。茉莉酸信号级联的交叉界保护表明，该研究将为植物和动物之间的信号保护过程提供见解。从植物激素研究中出现的配体介导的scf底物识别范式建立了一种传感生物系统中小分子的新机制，这可能对医学和人类健康具有深远的影响，包括开发针对人类E3泛素连接酶的药物的潜在新途径。最近茉莉酸盐作为抗癌药物的发现进一步表明，所提出的研究与发现新的肿瘤治疗药物有关。最后，这项工作将揭示病原微生物在疾病期间在真核宿主中协同选择信号通路的分子机制。对茉莉酸信号传导机制的研究将广泛有助于理解脂质衍生激素如何控制从植物到人类等多种多细胞生物的发育和免疫功能。研究配体介导的E3泛素连接酶对靶底物的识别将为小分子如何介导生物系统中的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，包括开发针对人类E3泛素连接酶的药物的潜在新途径。公共卫生相关性：拟议的研究将揭示致病微生物在疾病期间在真核宿主中选择信号通路的分子机制，并与发现针对肿瘤疾病的新型治疗药物相关。

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.