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（由申请人提供）：正确的蛋白质折叠是维持健康神经元（包括视网膜感光细胞）的关键问题。感光器蛋白质组上的压力可能是由环境因素（例如光损伤）或遗传因素（例如错误折叠突变）引起的。视紫红质和许多其他光感受器蛋白中的蛋白质组由一类称为分子伴侣的蛋白质维持，这些伴侣可以保护蛋白质免于聚集，引导其聚集。分子伴侣的一个重要类型是在真核细胞质中发现的 II 型伴侣蛋白，称为 CCT（含有无尾复合物多肽 1 的细胞质伴侣蛋白，也称为 TRiC）。需要 CCT 进行折叠的有数百个，其中包括形成 Gβγ 和 G 蛋白 β 亚基 (Gβ)。 Gβ5-RGS（G 蛋白信号传导调节剂）二聚体是视觉信号传导的关键组成部分，Gβγ 和 RGS-Gβ5 也需要 CCT 共伴侣蛋白（磷酸化蛋白样蛋白）才能正确折叠和二聚体形成。通过冷冻电子显微镜、化学交联与质谱联用以及位点特异性交联确定了 Gβγ 组装中的两种中间体的结构这些结构为 Gβγ 组装机制提供了分子细节。在目标 1 中，我们建议确定 RGS-Gβ5 组装中类似中间体的结构，以在分子水平上了解 CCT 和 PhLP1 如何协助 RGS-Gβ5。二聚体形成也已被证明是 CCT 在 Bardet-Biedl 综合征 (BBS) 中的另一个作用，BBS 是一种睫状功能障碍的遗传性疾病，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 是一种由八种蛋白质组成的复合物，对于囊泡运输至纤毛至关重要，也是一种由三种蛋白质组成的类 CCT 复合物，已知这些蛋白质的突变会导致 BBS（BBS 6、10 和 BBS）。 12）是 BBSome 组装所必需的。在目标 2 中，我们提出了类似的结构研究来确定 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至关重要。基于伴侣的方法治疗由 RGS-Gβ5 和 BBSome 功能障碍引起的视网膜疾病。