Structural Dynamics of Retinal Binding and Release

视网膜结合和释放的结构动力学

• 批准号: 8042471
• 负责人: David L Farrens
• 金额: $ 38.2万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2014-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8042471
• 关键词: Address; Affect; Affinity; Apoptosis; Arrestins; Attenuated; Binding; Biological Assay; Complex; Data; Disease; Event; Family; Funding; G Protein-Coupled Receptor Signaling; G-Protein-Coupled Receptors; GTP-Binding Proteins; Goals; Health; Human; Human Genome; Hydrolysis; Kinetics; Leber' s disease; Life; Light; Methods; Modeling; Molecular; Monitor; Mutagenesis; Mutation; Night Blindness; Nonexudative age-related macular degeneration; Opsin; Pharmaceutical Preparations; Pharmacologic Substance; Play; Process; Proteins; Research; Resolution; Retinal; Retinal Cone; Retinal Degeneration; Retinal Diseases; Retinitis Pigmentosa; Rhodopsin; Role; Scheme; Schiff Bases; Signal Transduction; Site; Structure; System; Testing; Time; Vertebrate Photoreceptors; Vision; Vision research; Visual; Visual Signal Transduction Pathway; Work; adduct; attenuation; base; chromophore; design; follow-up; insight; novel; preference; prevent; protein structure; receptor; receptor coupling; research study; theories; uptake

DESCRIPTION (provided by applicant): The long-term goal of our research is to understand the molecular mechanisms through which G-protein coupled receptors (GPCRs) are activated and attenuated. These receptors represent the largest family in the human genome, and they are the target of most pharmaceutical drugs. We focus our studies primarily on the GPCR rhodopsin and its affiliate proteins. Although crystal structures of key proteins involved in visual signaling are now known, most of the critical structural changes these proteins undergo during their activation and attenuation remain largely a matter of speculation. In particular, we lack even rudimentary information about the dynamic events involved in attenuating rhodopsin signaling, namely, the mechanisms through which retinal is released from the opsin-binding pocket, and how retinal binding and release affects arrestin binding and release. Understanding these processes is of fundamental importance for vision research - the stability of the retinal linkage varies widely among different opsins and is a factor in some visual disease states. Furthermore, although much is known about the mechanism and kinetics of arrestin binding to rhodopsin, little is known about what makes arrestin release after binding, and how this release is related to the status of the retinal chromophore. In Aim I of this proposal we will determine how rhodopsin controls the hydrolysis of its retinal Schiff base linkage. In Aim II we will examine how retinal uptake and release occurs in rhodopsin, using the recent structure of opsin to guide our studies. Finally, in Aim III, we will use our novel methods to follow up on a discovery we made during the last funding period - that arrestin can bind to MIII rhodopsin, thus trapping and preventing retinal release. Understanding how arrestin regulates retinal release is fundamentally important to health, as arrestin may serve to limit the release of free retinal under bright light conditions, and thus help limit the formation of oxidative retinal adducts that can contribute to diseases like atrophic age-related macular degeneration (AMD). Similarly, understanding what makes arrestin "let go" after binding rhodopsin is also crucial - stable rhodopsin-arrestin complexes have been suggested to be a contributing factor in apoptosis and autosomal dominant retinitis pigmentosa (ADRP). PUBLIC HEALTH RELEVANCE: The proposed research will define the molecular events involved in the binding and release of retinal. We will investigate how retinal gets into and out of the binding pocket in rhodopsin, what makes it stay there (i.e., how the Schiff-base linkage forms and hydrolyzes), and how the protein arrestin affects these processes. Answering these fundamental questions will help shed light on more general questions in vision, such as why rates of retinal binding and release vary so greatly between Rod and Cone rhodopsins, and help elucidate underlying mechanisms for several retinal diseases.

描述（由申请人提供）：我们研究的长期目标是了解 G 蛋白偶联受体 (GPCR) 被激活和减弱的分子机制。这些受体代表了人类基因组中最大的家族，它们是大多数药物的靶标。我们的研究主要集中在 GPCR 视紫红质及其附属蛋白上。尽管现在已知参与视觉信号传导的关键蛋白质的晶体结构，但这些蛋白质在激活和减弱过程中经历的大多数关键结构变化在很大程度上仍然是猜测的问题。特别是，我们甚至缺乏有关减弱视紫红质信号传导的动态事件的基本信息，即视网膜从视蛋白结合袋释放的机制，以及视网膜结合和释放如何影响视紫红质结合和释放。了解这些过程对于视觉研究至关重要——不同视蛋白之间视网膜连接的稳定性差异很大，并且是某些视觉疾病状态的一个因素。此外，尽管人们对视紫红质抑制蛋白与视紫红质结合的机制和动力学了解很多，但对于结合后抑制蛋白释放的原因以及这种释放与视网膜生色团状态的关系却知之甚少。在本提案的目标一中，我们将确定视紫红质如何控制其视网膜希夫碱键的水解。在《目标 II》中，我们将利用视蛋白的最新结构来指导我们的研究，研究视紫质中视网膜的摄取和释放是如何发生的。最后，在 Aim III 中，我们将使用我们的新方法来跟进我们在上一个资助期间所做的发现——视紫红质抑制蛋白可以与 MIII 视紫红质结合，从而捕获并阻止视网膜释放。了解视紫红质抑制蛋白如何调节视网膜释放对健康至关重要，因为视紫红质抑制蛋白可能有助于限制亮光条件下游离视网膜的释放，从而有助于限制氧化性视网膜加合物的形成，氧化性视网膜加合物可能导致萎缩性年龄相关性黄斑变性等疾病（AMD）。同样，了解抑制蛋白在结合视紫红质后“释放”的原因也至关重要——稳定的视紫红质-抑制蛋白复合物已被认为是细胞凋亡和常染色体显性视网膜色素变性（ADRP）的影响因素。 公共健康相关性：拟议的研究将定义与视网膜结合和释放有关的分子事件。我们将研究视黄醛如何进出视紫红质的结合袋，是什么让它留在那里（即希夫碱键如何形成和水解），以及蛋白视紫红质抑制蛋白如何影响这些过程。回答这些基本问题将有助于阐明视觉中更普遍的问题，例如为什么视杆视紫红质和视锥视紫红质的视网膜结合和释放速率差异如此之大，并有助于阐明几种视网膜疾病的潜在机制。