权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

The relationship between a molecular chaperone and protease : The discovery of NDP kinase like activity of a chaperone, and degeneration diseases.

分子伴侣与蛋白酶之间的关系：伴侣的 NDP 激酶样活性的发现和变性疾病。

基本信息

批准号：
14570121
负责人：
YANO Mihiro
金额：
$ 2.56万
依托单位：
The University of Tokushima
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14570121/
关键词：
Hsp70 Molecular chaperone Proteasome

项目摘要

<The chaperone functions in the ubiquitin-proteasome system>Cellular proteases and molecular chaperones play important roles in the intracellular protein catabolism. The ubiqitin-proteasome system (UPS) is a central component of the quality control mechanism that selectively degrades proteins. Among this pathway, it has been assumed that molecular chaperones activate proteasomal degradation by remodeling the conformation of protein substrate. Previously, we found that the 20S proteasome exhibits an ATP/ADP exchange activity other than proteolytic activities. Here we show that the 20S proteasome protects several heat-denatured proteins as to irreversible aggregation, leading to a maintenance of substrates in an unfolded state for subsequent degradation. Further, we found that VCP plays an important role in mediating the function of the UPS, by interacting with proteasome substrates before they are degraded. <The ATP/ADP exchange activity of Hsp7O and its reaction mechanism>We have previously reported that, in the presence of physiological concentrations of ATP and ADP, Hsp7O catalyses an ATP/ADP exchange reaction. In this study, we characterized the second metal-binding motif by site-directed mutagenesis and the crystal structure of the Hsp7O ATPase domain with bound ATP (Protein Data Bank code for Hsp70 ATPase domain, 1hjo), and found that the second metal-binding site, comprising a loop co-ordinated by His227, Glu231 and Asp232, participates in an ATP/ADP exchange reaction, in co-operation with the first metal-biding site. On the other hand, ADP bound to Hsp70 significantly inhibited the chaperone functionof Hsp70. These results may give an important clue for a better understanding of the ATP/ADP exchange reaction for repeated cycles of substrate binding/release by Hsp70.

<The chaperone functions in the ubiquitin-proteasome system>细胞蛋白酶和分子伴侣在细胞内蛋白质催化过程中起重要作用。泛肽-蛋白酶体系统（UPS）是选择性降解蛋白质的质量控制机制的核心组成部分。其中，分子伴侣通过改变蛋白质底物的构象来激活蛋白酶体的降解。以前，我们发现，20 S蛋白酶体表现出ATP/ADP交换活性以外的蛋白水解活性。在这里，我们表明，20 S蛋白酶体保护几个热变性蛋白质不可逆的聚集，导致基板在未折叠状态下的后续降解的维护。此外，我们发现，VCP在介导UPS的功能中起着重要的作用，通过与蛋白酶体底物相互作用，然后降解。<Hsp 7 O的ATP/ADP交换活性及其反应机理>我们以前曾报道，在生理浓度的ATP和ADP存在下，Hsp 7 O催化ATP/ADP交换反应。在这项研究中，我们通过定点突变和结合ATP的Hsp 7 O ATP酶结构域的晶体结构来表征第二个金属结合基序（Hsp 70 ATP酶结构域的蛋白质数据库代码，1hjo），并发现第二金属结合位点，包括由His 227、Glu 231和Asp 232配位的环，参与ATP/ADP交换反应，与第一金属结合位点合作。ADP与Hsp 70结合后，Hsp 70的分子伴侣功能受到明显抑制。这些结果可能会提供一个重要的线索，更好地理解ATP/ADP交换反应的底物结合/释放的Hsp 70的重复循环。