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Molecular mechanism of vacuolar processing system in differentiation of plant cell

植物细胞分化中液泡处理系统的分子机制

基本信息

批准号：
12304049
负责人：
HARA Ikuko
金额：
$ 30.01万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Dynamic transformation of vacuolar function is responsible for flexibility of differentiation and cell death events in higher plant cells. The aim of this study is to elucidate the molecular mechanism of vacuolar processing enzyme (VPE), which is known to be responsible for maturation and activation of vacuolar proteins, in the process of programmed cell death and cell differentiation.(1) We generated the Arabidopsis knockout mutants that had a defect of each gene for the two vegetative type VPEs, αVPE and γVPE, and one seed type VPE, βVPE. Then they were crossed to obtain double and triple mutants. From the analysis of the triple mutant, we found that normally processed storage proteins were no more detected, indicating that VPEs are a key enzyme in processing of seed storage proteins.(2) We found that a characteristic structure derived from ER, ER body. ER bodies develop in the epidermal cells of young seeding and contain the precursor proteins of stress-inducible protease such a VPE … More . In contrast, rosette leaves had no ER bodies. We found that wound stress induced the formation of many ER bodies in rosette leaves. It is possible that the biological function of ER bodies is related to defense systems in higher plants.(3) The process of controlled cell death in animals is well organized by caspases that are cysteine proteinases. In plants, many studies have shown that caspase-like activities are induced in dying cells. To identify a functional homolog of caspase in plants, we investigated hypersensitive cell death in tobacco mosaic virus (TMV)-infected tobacco plants. A VPE-specific inhibitor abolished the TMV-induced hypersensitive cell death, as did a caspase-1-specific inhibitor.Because VPE had caspase activity toward a caspase-1-specific substrate, the proteinase responsible for the caspase-1-like activity was identified as VPE. From the appearance of VPE activity at the early stage-of the TMV-induced hypersensitive response in tobacco leaves, it was suggested that VPE regulates the early process of the TMV-induced hypersensitive cell death. Less

液泡功能的动态转变负责高等植物细胞分化和细胞死亡事件的灵活性。本研究的目的是阐明液泡加工酶（VPE）的分子机制，该酶已知在程序性细胞死亡和细胞分化过程中负责液泡蛋白的成熟和激活。（1）我们生成了拟南芥敲除突变体，其两种营养型VPE（αVPE和γVPE）和一种种子型的每个基因都有缺陷 VPE，βVPE。然后将它们杂交以获得双突变体和三突变体。通过对三重突变体的分析，我们发现正常加工的贮藏蛋白不再被检测到，这表明VPEs是种子贮藏蛋白加工过程中的关键酶。(2)我们发现了源自ER、ER体的特征结构。 ER 体在幼苗的表皮细胞中发育，并含有应激诱导蛋白酶的前体蛋白，例如 VPE……更多。相比之下，莲座叶没有 ER 体。我们发现伤口应激诱导莲座叶中许多内质网小体的形成。 ER体的生物学功能可能与高等植物的防御系统有关。(3)动物中受控细胞死亡的过程是由半胱天冬酶(半胱氨酸蛋白酶)很好地组织的。在植物中，许多研究表明死亡细胞中会诱导半胱天冬酶样活性。为了鉴定植物中半胱天冬酶的功能同源物，我们研究了烟草花叶病毒（TMV）感染的烟草植物中的过敏细胞死亡。 VPE 特异性抑制剂消除了 TMV 诱导的过敏性细胞死亡，caspase-1 特异性抑制剂也是如此。由于 VPE 对 caspase-1 特异性底物具有 caspase 活性，因此负责 caspase-1 样活性的蛋白酶被鉴定为 VPE。从TMV诱导的烟叶过敏反应早期VPE活性的出现表明，VPE调节TMV诱导的过敏细胞死亡的早期过程。较少的