RIG: Biogenesis of Peptide Signals in Arabidopsis: Processing of Precursor Proteins

肽信号在拟南芥中的生物学作用在过去的十年中，肽信号被认为是参与植物生长发育、繁殖和防御的重要调控分子。与其他真核生物中的多肽激素类似，大多数植物调节肽是源自较大前体蛋白的细胞外信号。虽然在动物系统和酵母中研究得很透彻，但对植物中肽信号的合成、加工、储存和分泌的调控却知之甚少。本研究的主要目的是建立拟南芥中防御相关的AtPep1肽信号的细胞内生物发生途径。AtPep1来源于一个较大的激素前体（PROPEP1），似乎不是通过分泌途径合成的。PROPEP1加工酶尚未确定，AtPep1沉积在细胞壁外质体中与膜受体相互作用的机制尚不清楚。该研究计划将使用一种新型的双砷-四胱氨酸（TC）标记系统进行活细胞荧光成像，该系统具有独特的优势和能力，可以研究肽生物发生的动力学，并与电子显微镜和免疫细胞化学的超微结构分析相关。提出的研究代表了植物中肽激素的生物发生的第一个完整的特征。该结果将为今后利用药理学、生物化学和功能基因组工具联合鉴定加工酶和分离参与肽运输的分子载体奠定基础。更广泛的影响破译参与调控肽加工和分泌的非经典机制将提高我们对植物肽激素生物学的理解，以及真核生物防御肽信号的进化。由于AtPep1在先天免疫中的作用以及在作物中存在AtPep1同源物，本研究结果可能在未来通过作物生物技术提高植物对病虫害的抗性方面具有重要应用价值。本研究可能为TC标记系统在植物和其他生物中研究肽激素的生物发生提供新的应用。拟议的研究活动将在来自代表性不足群体的本科生的参与下进行，促进教育和社区外展。该研究将为本科生提供植物生物学方面的智力挑战和有意义的学习经验，以及现代细胞成像和分子生物学技术的使用。

BIOGENESIS OF PEPTIDE SIGNALS IN ARABIDOPSISIntellectual meritDuring the past decade peptide signals have been recognized as important regulatory molecules involved in plant growth and development, reproduction and defense. Similar to polypeptide hormones in other eukaryotes, most plant regulatory peptides are extracellular signals derived from larger precursor proteins. Although thoroughly studied in animal systems and yeast, the regulation of synthesis, processing, storage and secretion of peptide signals in plants is poorly understood. The main goal of this research is to establish the intracellular pathway for the biogenesis of the defense-related AtPep1 peptide signal in Arabidopsis. AtPep1 is derived from a larger prohormone precursor (PROPEP1) that appears not to be synthesized through the secretory pathway. PROPEP1 processing enzymes have not been identified, and the mechanism for AtPep1 deposition in the cell wall apoplast to interact with a membrane receptor is not known. The research plan will incorporate the use of a novel biarsenical-tetracysteine (TC) labeling system for live-cell fluorescent imaging that offers unique advantages and capabilities to study the dynamics of peptide biogenesis, correlated with ultrastructural analysis by electron microscopy and immunocytochemistry. The proposed study represents the first complete characterization of the biogenesis of a peptide hormone in plants. The results will be a foundation for future work on the identification of the processing enzymes, and the isolation of the molecular carriers involved in peptide transport, using a combination of pharmacological, biochemical and functional genomic tools. Broader impactDeciphering non-classical mechanisms involved in the processing and secretion of regulatory peptides will improve our understanding of the biology of peptide hormones in plants, and the evolution of defense peptide signaling in eukaryotes. Due to the role of AtPep1 in innate immunity and the presence of AtPep1 homologues in crop plants, the results of this research may have important applications in the future improvement of plant resistance against insect and pathogen attacks through crop biotechnology. This study may result in a new application of the TC tagging system to study peptide hormone biogenesis in plants and other organisms. The proposed research activities will be carried out with the participation of undergraduate students from underrepresented groups, fostering education and community outreach. The research will provide undergrads with intellectual challenges and meaningful learning experiences in plant biology and the use of modern cellular imaging and molecular biology techniques.