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Functional analysis of the Zn finger domain encoded by the ATRX gene whose mutations result in X-linked alpha thalassemia mental retardation(ATR-X) syndrome

ATRX基因编码的锌指结构域的功能分析，其突变导致X连锁α地中海贫血精神发育迟滞（ATR-X）综合征

基本信息

批准号：
18570170
负责人：
SUSUMU Inamoto
金额：
$ 2.63万
依托单位：
Kazusa DNA Research Institute (2007)Institute of Research and Innovation (2006)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18570170/
关键词：
ubiquitin ligase Zn finger domain 遺伝病

项目摘要

X-linked alpha thalassemia mental retardation (ATR-X) syndrome is caused by mutations in the ATRX gene. One of mutational hot spots is the region corresponding to the Zn finger domain of unknown function (ZnF1, ZnF2, and ZnF3) in its amino terminus. To reveal the cause of this genetic disorder, we explored the possibility that this domain functions as a ubiquitin ligase and that ubiquitinylation of chromatine related factors by this domain regulates gene expression.1. (1) We have shown the Zn finger domain is ubiquitinylated both in vivo and in vitro. (2) Ubiquitin ligase activity requires not only ZnF2-ZnF3 homologous to RING/PHD fingers known as ubiquitin ligases but also ZnF1 in their N-terminus. (3) Mutations of the Zn finger domain found in the ATR-X syndrome diminish the ligase activity. These results suggest that the Zn finger domain of ATRX constitutes a new family of ubiquitin ligase and that reduction of ligase activity gives rise to the ATR-X syndrome.2. Far UV CD measurements of wild type ZnF (1, 2, 3) and its mutant in ZnF1 have indicated disruption of the ZnF1 structure alone results in distortion of the overall structure of the Zn finger domain, which might lead to loss of its enzymatic activity.3. Three human genes (ATRXLα, ATRXβ, and ATRXLγ) encoding proteins with ATRX-like Zn finger domains were identified and isolated ATRX-like Zn finger domains from these proteins were also shown to have ubiquitin ligase activity in vitro.4. Drosophila ATRX genes were identified. Interestingly, Drosophila ATRX is encoded by two genes ; namely, dATRXN and dATRXC which contain the Zn finger domain and the helicase domain, respectively. The ubiquitin ligase activity was not, however, detected in the isolated Zn finger domain of dATRXN. HP1 and HDAC1, known to interact with ATRX, were not ubiquitinylated by ATRX.

X连锁α地中海贫血智力低下（ATR-X）综合征是由ATRX基因突变引起的。突变热点之一是其氨基端与未知功能的锌指结构域（ZnF 1、ZnF 2和ZnF 3）对应的区域。为了揭示这种遗传疾病的原因，我们探索了该结构域作为遍在蛋白连接酶的功能以及该结构域对染色质相关因子的遍在蛋白化调节基因表达的可能性。1. (1)我们已经证明了锌指结构域在体内和体外都是泛素化的。(2)泛素连接酶活性不仅需要与称为泛素连接酶的RING/PHD指同源的ZnF 2-ZnF 3，而且需要在其N-末端的ZnF 1。(3)在ATR-X综合征中发现的锌指结构域的突变降低了连接酶活性。这些结果表明ATRX的锌指结构域构成了一个新的泛素连接酶家族，连接酶活性降低导致ATR-X综合征.对野生型ZnF（1，2，3）及其突变体ZnF 1的远紫外CD测量表明，ZnF 1结构的单独破坏导致Zn指结构域的整体结构畸变，这可能导致其酶活性的丧失.鉴定了三个编码具有ATRX样锌指结构域的蛋白质的人类基因（ATRXLα、ATRXβ和ATRXLγ），并且从这些蛋白质中分离的ATRX样锌指结构域在体外也显示出具有泛素连接酶活性.鉴定了果蝇ATRX基因。有趣的是，果蝇ATRX由两个基因编码;即dATRXN和dATRXC，其分别含有Zn指结构域和解旋酶结构域。然而，在dATRXN的分离的锌指结构域中没有检测到泛素连接酶活性。已知与ATRX相互作用的HP 1和HDAC 1未被ATRX泛素化。