Characterization of Ubiquitin Pathway in Higher Plants

蛋白质的翻译后修饰调节着重要的生理生化过程。一种这样的修饰是蛋白质泛素的共价附着。在真核生物中，只有一小部分泛素-蛋白偶联作用被证实。泛素被研究得最多的角色是作为一种可重复使用的标签来标记蛋白质水解。在植物中，已发现它附着在光感受器光敏色素和烟草花叶病毒的外壳蛋白上。本研究旨在探讨泛素在高等植物生理过程中的作用。生化分析研究了泛素蛋白偶联物在拟南芥中的亚细胞定位。高等植物中泛素基因表达的分子分析包括：1)从拟南芥中分离泛素延伸基因家族的剩余成员；2)确定泛素延伸基因家族不同成员的表达调控；3)通过缺失分析和定点诱变以及重新引入植物来确定泛素延伸基因的启动子区域。​泛素是一种广泛存在于植物、动物、酵母和细菌细胞中的蛋白质。它是已知的高度保守的蛋白质之一，在人类蛋白质和高等植物蛋白质之间只有三个氨基酸的差异。它在细胞中起着许多重要的生物学作用，最充分的特征是它在标记蛋白质分解，特别是异常蛋白质方面的作用。目前对泛素途径调控的理解是初步的。因此，这些研究的目的是为高等植物中泛素通路的调控及其基因的调控提供基础信息

Post-translational modifications of proteins regulate important physiological and biochemical processes. One such modification is the covalent attachment of the protein ubiquitin. Only a small subset of the roles of ubiquitin- protein conjugation has been characterized in eukaryotes. Ubiquitin's most well-studied role is as a reusable tag marking proteins for proteolysis. In plants, it has been found attached to the photoreceptor phytochrome and the coat protein of Tobacco Mosaic Virus. The purpose of this research is to explore the function of ubiquitin in physiological processes in higher plants. The biochemical analysis examines the subcellular localization of ubiquitin- protein conjugates in Arabidopsis. The molecular analyses of ubiquitin gene expression in higher plants involve 1) isolation of the remaining member(s) of the ubiquitin extension gene family from Arabidopsis, 2) determination of the regulation of expression of different members of the ubiquitin extension gene family and 3) definition of the promoter regions for the ubiquitin extension genes by deletion analysis and site-directed mutagenesis and re- introduction into plants. Ubiquitin is a protein that is widely distributed in plant, animal, yeast and bacterial cells. It is one of the most highly conserved proteins known, having only three amino acid differences between the human and higher plant protein. It serves a number of important biological roles in the cell, the most fully characterized being its role in marking proteins for breakdown, especially abnormal proteins. Current understanding of the regulation of the ubiquitin pathway is rudimentary. Therefore, the goal of these studies is to provide fundamental information on the regulation of the ubiquitin pathway and the regulation of their genes in higher plants.***