Mechanisms of assembly of photoreceptor G protein complexes

光感受器G蛋白复合物的组装机制

• 批准号: 9027221
• 负责人: BARRY M WILLARDSON
• 金额: $ 36.05万
• 依托单位: BRIGHAM YOUNG UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-03 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9027221
• 关键词: Actins; Address; Adolescence; Alzheimer' s Disease; Amyotrophic Lateral Sclerosis; Area; Attention; Bardet-Biedl Syndrome; Blindness; Cell Death; Chemicals; Cilia; Collaborations; Complex; Coupled; Cryoelectron Microscopy; Cytosol; Defect; Detection; Disease; Electrons; Endoplasmic Reticulum; Environmental Risk Factor; Foundations; Functional disorder; GTP-Binding Protein Regulators; GTP-Binding Proteins; Genes; Genetic; Hereditary Disease; Homeostasis; Huntington Disease; Investigation; Knock-out; Knowledge; Light; Mass Spectrum Analysis; Mediating; Membrane Proteins; Methods; Molecular; Molecular Chaperones; Motivation; Mutate; Mutation; Nature; Nerve Degeneration; Neurodegenerative Disorders; Neurons; PDC gene; Parkinson Disease; Pathway interactions; Photoreceptors; Physiological; Process; Proteins; Proteome; Resolution; Retina; Retinal; Retinal Cone; Retinal Degeneration; Retinal Diseases; Rhodopsin; Role; Signal Transduction; Site; Stress; Structure; System; Techniques; Therapeutic; Time; Tubulin; Vesicle; Visual; Work; X-Ray Crystallography; base; chaperonin; crosslink; cytosolic chaperonin; design; dimer; in vivo; phosducin-like protein; polypeptide; protein aggregation; protein complex; protein folding; protein misfolding; public health relevance; retinal rods; stem; trafficking; unnatural amino acids

 DESCRIPTION (provided by applicant): Proper protein folding is a key issue in maintaining healthy neurons, including the photoreceptor cells of the retina. Stresses on the photoreceptor proteome may be caused by environmental factors such as light damage or by genetic factors such as misfolding mutations in rhodopsin and many other photoreceptor proteins. The proteome is maintained by a class of proteins called molecular chaperones. These chaperones protect proteins from aggregation, channel their folding pathways and facilitate their association into multi-protein assemblies. An important type of molecular chaperone is the type II chaperonin found in the eukaryotic cytosol, termed CCT (Cytosolic Chaperonin containing Tailless complex polypeptide 1, also called TRiC). The number of proteins known to require CCT for their folding is in the hundreds and continues to grow. Among these are the G protein β subunits (Gβ) which form the Gβγ and Gβ5-RGS (Regulator of G protein Signaling) dimers that are key components in visual signaling. Both Gβγ and RGS-Gβ5 also require the CCT co-chaperone, phosducin-like protein, for proper folding and dimer formation. In previous work, we have determined the structures of two intermediates in Gβγ assembly by cryo-electron microscopy, chemical cross-linking coupled with mass spectrometry, and site-specific cross-linking with unnatural amino acids. These structures have provided molecular detail into the mechanism of Gβγ assembly. In Aim 1, we propose to determine the structures of similar intermediates in RGS-Gβ5 assembly to understand at the molecular level how CCT and PhLP1 assist in RGS-Gβ5 dimer formation. An additional role for CCT in Bardet-Biedl syndrome (BBS) has also been demonstrated. BBS is a genetic disease of ciliary dysfunction characterized by multiple pathological conditions including retinal degeneration. BBS is caused by an inability to form the BBSome, a complex of eight proteins that is essential for vesicle trafficking to cilia. CCT and a CCT-like complex made up of three proteins whose mutations are known to cause BBS (BBS 6, 10 and 12) are required for the assembly of the BBSome. In Aim 2, we propose similar structural studies to determine the molecular mechanism of BBSome assembly and BBSome function. The information gained from these studies will be vital in designing chaperone-based methods to treat retinal diseases caused by RGS-Gβ5 and BBSome malfunctions.

 描述（由应用提供）：正确的蛋白质折叠是维持健康神经元（包括视网膜的感光细胞）的关键问题。受感受器蛋白的应力可能是由环境因素（例如光损伤或遗传因素）引起的，例如在视紫红质和许多其他光感受器蛋白中折叠突变。该蛋白质由一类称为分子伴侣的蛋白质维持。这些伴侣保护蛋白质免受聚集的影响，引导其折叠途径并将其缔合为多蛋白组件。一个重要的分子链酮类型是在真核细胞质中发现的II型链蛋白，称为CCT（含有无讽刺的复合物多肽1，也称为Tric）。已知需要CCT折叠的蛋白质的数量在数百次中，并继续增长。其中包括G蛋白β亚基（Gβ），该亚基形成了Gβγ和Gβ5-RG（G蛋白信号传导的调节剂）二聚体，这些二聚体是视觉信号传导中的关键组成部分。 Gβγ和RGS-Gβ5都需要CCT副酮，磷素样蛋白，才能正确折叠和二聚体形成。在先前的工作中，我们通过冷冻电子显微镜，化学交联与质谱和特定于位点特异性的交联与非天然氨基酸一起确定了Gβγ组装中两个中间体的结构。这些结构为Gβγ组装机理提供了分子细节。在AIM 1中，我们建议确定RGS-Gβ5组装中相似中间体的结构，以在分子水平上了解CCT和PHLP1如何有助于RGS-Gβ5二聚体形成。 CCT在Bardet-Biedl综合征（BBS）中的另一个作用也已被证明。 BBS是一种睫状功能障碍的遗传疾病，其特征是多种病理状况，包括视网膜变性。 BBS是由于无法形成BBSOME引起的，BBSOME是八种蛋白质的复合物，这对于囊泡运输到纤毛必不可少。 CCT和CCT样复合物由三种蛋白质组成，其突变被称为BBS（BBS 6、10和12）是BBSOME的组装所必需的。在AIM 2中，我们提出了类似的结构研究，以确定BBSOME组装和BBSOME功能的分子机制。从这些研究中获得的信息对于设计基于伴侣的方法来治疗由RGS-Gβ5和BBSOME故障引起的残留疾病至关重要。