Polypeptide Signaling in Plants: Structure, Function, Evolution and Mechanism of Action of Systemin and Its Precursor, Prosystemin

9601099 Ryan本研究的目的是了解参与200个氨基酸的激素原蛋白质，前系统素的合成和储存的基本过程，以及18个氨基酸的多肽激素，系统素的加工，释放和接收模式的机制，系统素来源于前系统素，以响应草食动物攻击的伤害。将鉴定合成前系统素的特定细胞类型，并确定其胞间或胞内储存的位点。将研究创伤导致系统素从前系统素中加工和释放的机制，并将进行鉴定特定的新型加工酶的研究。将对加工酶进行纯化和表征。将研究番茄植株中系统素的运输方式，并在生物化学和亚细胞水平上研究其在靶细胞中的接受机制。将鉴定、纯化和克隆被系统素激活的蛋白质的全谱。前系统素蛋白，在E.大肠杆菌表达系统，将大量生产，以确定其三维结构，并将其结构特征与其储存和加工相关联。整个植物界的原系统素同源物的发生将系统地寻求使用原系统素抗体，cDNA杂交分析，和PCR分析。将研究前系统素和系统素在系统激活番茄以外的植物物种中的防御基因中的作用。将检查系统素以外的多肽激素可能来源于前系统素蛋白的可能性。系统素是迄今为止在植物中鉴定的唯一肽类激素。它在植物防御昆虫和其他侮辱中发挥作用。这项研究将有助于我们从根本上了解植物如何科普它们在生命周期中遇到的压力。

9601099 Ryan The objective of this research is to understand the fundamental processes involved in the synthesis and storage of the 200 amino acid prohormone protein, prosystemin, and the mechanisms of processing, release and mode of reception of the 18 amino acid polypeptide hormone, systemin, that is derived from prosystemin in response to wounding by herbivore attacks. The specific cell types in which prosystemin is synthesized will be identified and the sites of its inter- or intracellular storage will be established. The mechanism by which wounding causes processing and release of systemin from prosystemin will be studied, and research to identify the specific novel processing enzymes will be carried out. The processing enzymes will be purified and characterized. The mode of transport of systemin in tomato plants will be investigated and the mechanism(s) of its reception in target cells will be studied at the biochemical and subcellular levels. The full spectrum of proteins that are activated by systemin will be identified, purified and cloned. Prosystemin protein, produced in an E. coli expression system, will be produced in mg quantities to determine its three dimensional structure, and to relate the stuctural features to its storage and processing. The occurrence of prosystemin homologs throughout the plant kingdom will be systematically sought using prosystemin antibodies, cDNA hybridization analyses, and PCR analyses. The role of prosystemin and systemin in systemically activating defense genes in plant species other than tomato will be studied. The possiblity that polypeptide hormones other than systemin may be derived from the prosystemin protein will be examined. Systemin is the only peptide hormone identified in plants to date. It has a role in plant defense against insects and other insults. This research will contribute to our fundamental understanding of how plants cope with stresses that they encounter during their life cycle.