Regulation of defense signaling in tomato

描述(由申请人提供)：植物激素茉莉酸(JA)控制宿主免疫和发育的不同方面。对模式植物拟南芥和番茄(Solanum Lycpersicum)的研究表明，Jasmonate反应基因的转录严格需要E3泛素连接酶SCFCOI1。JAZ(茉莉酸ZIM结构域)蛋白通过与基本螺旋-环-螺旋转录因子MYC2相互作用来抑制茉莉酸反应基因的表达。作为对茉莉酸信号的响应，JaZ蛋白受到SCFCOI1介导的泛素化的影响，随后被26S蛋白酶体降解。JA-氨基酸共轭茉莉酸异亮氨酸(JA-Ile)刺激JaZ阻遏物与F-box蛋白COI1的结合。冠菌素是一种由植物病原菌产生的毒素，它强烈促进COI1-Jaz的相互作用。这项拟议的研究将以拟南芥和番茄为实验模型系统，提出以下假设：COI1是JA-Ile和Coronatine的受体，JaZ抑制蛋白决定了SCFCOI1控制茉莉酸调控过程多样性的特异性。我们将结合生物化学、遗传学和细胞生物学的方法来解决以下具体目标：1)确定COI1和Jaz在茉莉酸配体结合中的作用；2)测量JA-Ile和其他JA-氨基酸结合物在健康、受伤和疾病组织中的内源水平；3)确定Jaz家族成员的生理功能；4)确定Jaz阻遏物的CT端结构域中与COI1和MYC2相互作用的区域；以及5)确定Jaz-Jaz二聚体在调节茉莉酸反应中的作用。这项研究将有助于更广泛地理解脂源性激素控制多细胞生物体发育和免疫功能的分子机制。对茉莉酸信号级联组成成分的交叉保守表明，这项研究将为深入了解植物和动物之间保守的信号过程提供洞察力。从植物激素研究中产生的配体介导的SCF底物识别范式建立了一种新的机制来感知生物系统中的小分子，这可能对药物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。最近发现的茉莉酸酯作为抗癌药物进一步表明，拟议的研究与发现新的治疗肿瘤疾病的药物有关。最后，这项工作将揭示致病微生物在疾病期间选择真核宿主中的信号通路的分子机制。对茉莉酸信号转导机制的拟议研究将有助于更广泛地了解脂源性激素如何控制从植物到人类的各种多细胞生物体的发育和免疫功能。对E3泛素连接酶配体介导的靶底物识别的研究将为小分子如何在生物系统中介导蛋白质相互作用提供新的信息，这可能对医学和人类健康具有深远的意义，包括开发针对人类E3泛素连接酶的药物的潜在新途径。与公共卫生相关：拟议的研究将揭示致病微生物在疾病期间选择真核宿主中的信号通路的分子机制，并与发现治疗肿瘤疾病的新药物有关。

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.