Structural Basis of Rhodopsin Function

视紫质功能的结构基础

• 批准号: 7281184
• 负责人: JAVIER V NAVARRO
• 金额: $ 25.66万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-15 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7281184
• 关键词: 11 cis Retinal; Address; Appendix; Bacteriorhodopsins; Binding; Binding Proteins; Bos taurus; Cattle; Chemicals; Collaborations; Complex; Condition; Crystallization; Electronics; Environment; Equilibrium; Esthesia; Exhibits; Eye diseases; Family; G-Protein-Coupled Receptors; GTP-Binding Proteins; Helix (Snails); Hormonal; Hydrogen Bonding; Lead; Light; Link; Localized; Maps; Measurement; Mediating; Medicine; Methodology; Molecular; Movement; Mutation; Night Blindness; Numbers; Object Attachment; Opsin; Pathway interactions; Pharmaceutical Preparations; Phase; Photobleaching; Photons; Photoreceptors; Physiological Processes; Positioning Attribute; Principal Investigator; Property; Proteins; Reaction; Relaxation; Resolution; Retinal; Retinal Dystrophy; Retinal Pigments; Rhodopsin; Roentgen Rays; Schiff Bases; Sensory; Sensory Rhodopsins; Signal Transduction; Staging; Structural Protein; Structure; Time; Transducin; Vertebrate Photoreceptors; Vision; Water; absorption; aqueous; base; bathorhodopsin; chromophore; cis trans isomerization; cold temperature; ear helix; flash photolysis; improved; insight; lumirhodopsin; member; metarhodopsin; metarhodopsin II; metarhodopsins; mutant; neurotransmission; photorhodopsin; programs; protein structure; receptor; response

DESCRIPTION (provided by applicant): Rhodopsin is the photoreceptor responsible for dim light vision, and represents the paradigm for the large superfamily of G protein-coupled receptors (GPCRs). The importance of rhodopsin in vision and in medicine is demonstrated by the fact that its mutants are linked to various retinal dystrophies, and mutations causing constitutive activity of rhodopsins are linked to congenital stationary night blindness. Rhodopsin has the canonical seven transmembrane helices, which delineate the pocket for the 11-cis retinal chromophore that is bound to Lys296 via a protonated Schiff base. The X-ray structure of ground-state bovine rhodopsin has been elucidated to 2.8A resolution. Determining this high-resolution X-ray structure was a major step toward developing an understanding of rhodopsin's function; however, elucidating its mechanism of activation requires knowing the high-resolution structures of intermediates along the reaction pathway, as well as their modes of interaction with transducin. Specifically, we will ask how does retinal photoisomerization trigger protein structural changes that lead to activation of transducin, thereby initiating the sensation of vision. Our major hypothesis is that light triggers the rapid isomerization of the retinal, a change which the protein both accommodates and subsequently amplifies into the larger structural changes required for signaling. We are in a unique position to address this hypothesis, as we have recently achieved a higher resolution structure of rhodopsin and have for the first time identified internal water molecules unambiguously. Furthermore, we have trapped photo-intermediates of rhodopsins in the crystals and shown that they diffract. The aims of this project are to map, at unprecedented spatial and temporal resolution, the structural transformations that occur upon activation of rhodospin by solving the X-ray structures of the photo-intermediates bathorhodopsin, lumirhodopsin and metarhodopsin (The latter is the signaling state of rhodopsin). Most importantly, we will elucidate the crystal structure of the metarhodopsin-transducin complex in order to identify the interactions at the interface of this signaling unit. Accomplishing these Specific Aims will define the physical and chemical basis for the activation of rhodopsin. Furthermore, structural studies at high resolution will open the way for understanding the molecular basis for the unique photobleaching properties of rod and cone visual pigments.

描述(申请人提供)：视紫红质是负责弱光视觉的光感受器，代表了G蛋白偶联受体(GPCRs)超家族的范例。视紫红质在视觉和医学上的重要性被证明是因为它的突变与各种视网膜营养不良有关，而导致视紫红质结构性活性的突变与先天性静止性夜盲有关。视紫红质具有典型的七个跨膜螺旋，描绘了11顺式视网膜发色团的口袋，该发色团通过质子化的希夫碱与Lys296结合。牛视紫质的基态X射线结构已被阐明为2.8A分辨率。确定这种高分辨率X射线结构是发展对视紫红质功能的理解的重要一步；然而，阐明其激活机制需要知道反应途径上的中间体的高分辨率结构，以及它们与转导蛋白相互作用的模式。具体地说，我们将询问视网膜光异构化如何触发蛋白质结构变化，从而导致转导蛋白的激活，从而启动视觉感觉。我们的主要假设是，光触发视网膜的快速异构化，蛋白质既适应这种变化，又随后放大为信号所需的更大的结构变化。我们处于一个独特的位置来解决这一假说，因为我们最近获得了视紫红质的更高分辨率结构，并首次明确地确定了内部水分子。此外，我们还在晶体中捕获了视紫红质的光中间体，并显示了它们的衍射性。这个项目的目的是以前所未有的空间和时间分辨率，通过解决光中间体底视紫质、光视紫质和后视紫红质(后者是视紫红质的信号状态)的X射线结构，绘制在罗多司平被激活时发生的结构变化。最重要的是，我们将阐明后视紫红质-转导蛋白复合体的晶体结构，以确定该信号单位界面的相互作用。实现这些特定的目标将确定视紫红质激活的物理和化学基础。此外，高分辨率的结构研究将为理解棒状和锥形视觉颜料独特的光漂白性能的分子基础开辟道路。