Structures and functions of the human Josephin domain-containing proteins

人类约瑟芬结构域蛋白的结构和功能

基本信息

批准号：
8303311
负责人：
Patrick J Loll
金额：
$ 33.12万
依托单位：
DREXEL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-30 至 2014-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8303311
关键词：
Alzheimer&apos s Disease Ataxia Binding Biochemical Biological Biological Process C-terminal Cell physiology Cells Cerebellar Ataxia Chemicals Cleaved cell Complex Cysteine Protease Degradation Pathway Deubiquitinating Enzyme Disease Distant Endoplasmic Reticulum Enzymes Eukaryota Family Family member Glutamine Homeostasis Homologous Gene Human Human Genome Huntington Disease Inherited Length Link MJD1 protein Machado-Joseph Disease Methods Molecular Molecular Probes Molecular Structure N-terminal Nerve Degeneration Parkinson Disease Pathway interactions Plants Play Polyubiquitin Proteins Quality Control Relative (related person)Role Specificity Spinal Structure Tertiary Protein Structure Testing Toxic effect Ubiquitin Work X-Ray Crystallography base insight member polyglutamine preference protein function protein misfolding research study structural biology therapy design

项目摘要

The Josephin domain-containing proteins are one of the five major families of deubiquitinating enzymes (DUBs). The founding member of the family is ataxin-3, a polyglutamine protein and the causative agent of the most common inherited ataxia, spinal cerebellar ataxia type 3 (SCA3, also known as Machado-Joseph disease). Ataxin-3's DUB activity resides in the molecule's N-terminal half, the so-called Josephin domain. Ataxin-3 is linked to many cellular processes that are related to maintaining protein homeostasis, including the transport of misfolded proteins to aggresomes and the flux of proteins through the endoplasmic reticulum- associated degradation pathway (ERAD). Ataxin-3 can also suppress the toxicity of expanded repeat polyglutamine domains. All of these functions require DUB activity, establishing the biological significance of the Josephin domain and hinting at a link between Josephin DUB activity and neurodegeneration induced by protein misfolding. Three homologs of ataxin-3 are encoded in the human genome: The ataxin-3-like protein (AT3L), Josephin-1, and Josephin-2. All three possess DUB activity, but differ substantially in catalytic efficiency and specificity. Josephin domain-containing homologs are conserved in most eukaryotes, including plants and protozoans, implying that this domain and the DUB activity it expresses are responsible for valuable biological functions. We propose to analyze the molecular structure and function of the human Josephin domain-containing proteins in order to understand how they recognize and act upon substrates and other interacting proteins. We will use X-ray crystallography to determine structures for different Josephin domains, alone and in complex with ubiquitin substrates; characterize the DUB activities of the four human Josephin domain-containing proteins, assessing how they bind and cleave both small and large ubiquitin substrates; explore their ubiquitin- binding activities; and probe the interactions of ataxin-3 with its cellular binding partners.

含有 Josephin 结构域的蛋白质是去泛素化酶的五个主要家族之一（配音）。该家族的创始成员是 ataxin-3，一种聚谷氨酰胺蛋白，也是该疾病的致病因子最常见的遗传性共济失调，脊髓小脑性共济失调 3 型（SCA3，也称为 Machado-Joseph 疾病）。 Ataxin-3 的 DUB 活性位于分子的 N 末端一半，即所谓的 Josephin 结构域。 Ataxin-3 与许多与维持蛋白质稳态相关的细胞过程有关，包括将错误折叠的蛋白质转运至聚集体以及蛋白质通过内质网的流动相关降解途径（ERAD）。 Ataxin-3 还可以抑制扩增重复序列的毒性聚谷氨酰胺结构域。所有这些功能都需要 DUB 活性，从而确立了 DUB 的生物学意义 Josephin 结构域并暗示 Josephin DUB 活性与由蛋白质错误折叠。人类基因组中编码了 ataxin-3 的三种同源物： ataxin-3 样蛋白 (AT3L)、约瑟芬-1 和约瑟芬-2。这三种都具有 DUB 活性，但催化效率和特异性。含有 Josephin 结构域的同系物在大多数真核生物中都是保守的，包括植物和原生动物，这意味着该结构域及其表达的 DUB 活性负责有价值的生物功能。我们建议分析人类 Josephin 结构域的分子结构和功能蛋白质，以了解它们如何识别底物和其他相互作用的蛋白质并对其起作用。我们将使用 X 射线晶体学来确定不同 Josephin 域的结构，单独的和复杂的具有泛素底物；表征四种人类 Josephin 结构域的 DUB 活性蛋白质，评估它们如何结合和切割小和大泛素底物；探索它们的无处不在—— 约束活动；并探究 ataxin-3 与其细胞结合伴侣的相互作用。