The Role of Leucine Aminopeptidase in Plant Defense

9318260 Walling氨肽酶是水解肽和蛋白质中n端氨基酸的外肽酶。在动物中，氨基肽酶通过将肠道和脑肽激素转化为活性或非活性形式，在营养和调节肠道和脑肽激素活性方面发挥重要作用。此外，这些外肽酶可能在体内调节蛋白质的半衰期中起作用。令人惊讶的是,对植物发育过程中氨基肽酶的活性了解甚少。虽然已知氨肽酶在萌发后和衰老过程中被诱导，但这些基因在植物生命周期或对生物或非生物胁迫的反应中的表达尚未被表征。Walling博士从番茄中分离并鉴定了亮氨酸氨基肽酶（lap） cDNA克隆。在机械损伤、昆虫摄食和丁香假单胞菌感染后，亮氨酸氨基肽酶mrna被诱导到高水平。番茄感染。损伤后也会诱导LAP蛋白及其活性。番茄中存在两种伤致lap基因。本研究旨在从多方面了解lap在植物防御反应中的表达、定位和功能。此外，这些研究将扩展到全面了解lap基因在植物发育过程中的表达和对非生物胁迫的响应。直到最近，植物亮氨酸氨基肽酶基因才被分离出来，并且很少有直接的努力来了解它们的表达及其对植物对环境和发育线索的反应的影响。阐明LAPs在植物防御反应和发育过程中的作用将增强我们对有利于最佳生长和发育的机制的理解。这些因素将直接影响作物的最佳生产力，并可能为提高植物内源保护机制的策略提供见解。＊＊＊

9318260 Walling Aminopeptidases are exopeptidases that hydrolyze the N-terminal amino acid from peptides and proteins. In animals, aminopeptidases have an important role in nutrition and modulation of the activities of gut and brain peptide hormones by converting them to active or inactive forms. In addition, these exopeptidases may have a role in modulating half-lives of proteins in vivo. Surprisingly; little is known about aminopeptidase activity during plant development. Although aminopeptidases are known to be induced after germination and during senescence, the expression of these genes during the plant life cycle or in response to biotic or abiotic stress has not been characterized. Dr. Walling has isolated and characterized a leucine aminopeptidase (lap) cDNA clone from Lycopersicon exculentum (tomato). Leucine aminopeptidase mRNAs are induced to high levels after mechanical injury, insect feeding, and Pseudomonas syringae pv. tomato infection. LAP proteins and activity are also induced after wounding. Two wound-induced lap genes are present in the tomato. The proposed research is a multi-faceted approach to understanding the expression, localization, and function of LAPs during the plant-defense response. Furthermore, these studies will be exteded to gain a comprehensive understanding of lap gene expression throughout plant development and in response to abiotic stress. Only recently, have plant leucine aminopeptidase genes been isolated, and few directed efforts have been made to understand their expression and impact on the plant responses to the environment and to developmental cues. Elucidation of the role of LAPs during the plant defense reaction and during development will enhance our understanding of the mechanisms that favor optimal growth and development. These factors will directly impact on optimal crop productivity and potentially yield insights for strategies to enhance a plant's endogenous protection mechanisms. ***