Photobiology of Rhodopsin and the Cone Pigments

视紫红质和视锥细胞色素的光生物学

• 批准号: 7769862
• 负责人: ROBERT Richards BIRGE
• 金额: $ 22.72万
• 依托单位: UNIVERSITY OF CONNECTICUT STORRS
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-08-01 至 2013-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7769862
• 关键词: Address; Adopted; Adoption; Belief; Binding; Binding Sites; Biochemical; Biological; Budgets; Cells; Charge; Code; Communities; Comparative Study; Complex; Computer software; Development; Electronics; Electrostatics; Eye diseases; Funding; G Protein-Coupled Receptor Genes; Goals; Grant; Homology Modeling; Human; Individual; Instruction; Light; Linux; Mechanics; Methods; Modeling; Molecular; Molecular Conformation; Motion; Nature; Nerve; Noise; Organic Chemistry; Photobiology; Photobleaching; Photoreceptors; Pigments; Procedures; Process; Property; Protein Binding; Proteins; Quantum Mechanics; Quantum Theory; Recovery; Relative (related person); Research; Research Personnel; Rest; Retinal; Retinal Cone; Retinal Photoreceptors; Retinal Pigments; Rhodopsin; Site-Directed Mutagenesis; Spectrum Analysis; Staging; Structure; Structure-Activity Relationship; Temperature; Time; Transducin; United States National Institutes of Health; Vision; Vision research; absorption; base; chromophore; disorder of macula of retina; experience; graphical user interface; improved; interest; light intensity; molecular orbital; neglect; photoactivation; programs; public health relevance; quantum; receptor; theories; tool; vibration; vision blue pigment; visual process; visual processing

DESCRIPTION (provided by applicant): Cone cells are responsible for photopic vision, the visual process under normal light conditions. The cone receptors must operate over a wide range of light intensities and cover the full range of the visible spectrum. The ability to function under these diverse conditions is due primarily to the highly optimized GPCR light-transducing proteins informally called cone pigments. These proteins have absorption maxima that range from 350 to 660 nm, and upon the absorption of light, undergo an efficient photobleaching sequence to produce an activated protein. Subsequent binding of transducin to the activated protein results in a nerve impulse and vision. A key observation made during the previous NIH funded study was that cone pigments undergo a counterion switch during photoactivation. A key aim of this study is to explore whether a counterion switch mechanism is also active in the red and blue cone pigments, and if so, to characterize the molecular details. To achieve this goal, we will use vibrational and electronic spectroscopy at temperatures from 10K to ambient to trap and characterize the photobleaching intermediates. Site directed mutagenesis will be used to identify the key residues responsible for wavelength selection and the nature of the counterion switch. It is clear from homology studies that many of the red cones differ from the green, blue and UV cones in nature and implementation of the counterion switch. Indeed, it is possible that the red cones lack this mechanistic feature entirely. An additional aim of this study is to systematically identify the mechanisms of wavelength selection in the UV, blue, green and red cones. Although our research identified key features of wavelength selection in the blue and UV cones, much remains to be understood. Our inclusion of the red cones in this study is new, and our enthusiasm for this topic rests in part on our belief that the red cones are fundamentally different. We have preliminary evidence, presented in our preliminary studies discussion, that the deep red cones use at least one new mechanism for wavelength selection involving manipulation of the chromophore ring conformation. The combination of unique wavelength selection and a significantly different (or absent) counterion switching mechanism make the red cones an important target. Our studies will include the use of molecular orbital theory to probe structure-function relationships in the cone pigments, and to calculate the spectroscopic properties of the bound chromophores. We will refactor our MNDO-PSDCI code and improve the interface to make these procedures more useful to the scientific community. As before, we will provide these procedures to interested researchers without charge. PUBLIC HEALTH RELEVANCE: There is a growing need to understand the photobleaching and recovery mechanisms associated with light exposure in cone photoreceptors. Because these cells are essential for human photopic vision, it is important to understand the structure and function relationships in the associated light transducing pigments. The project goals of this research may help understand macular disease, which involves loss of cone cells, cone dystrophy, and other eye diseases, which involve damage or diminished function of retinal photoreceptors.

描述（由申请人提供）：锥细胞负责光波视觉，即正常光条件下的视觉过程。圆锥体受体必须在各种光强度范围内运行，并覆盖可见光谱的全部范围。在这些不同条件下运作的能力主要是由于高度优化的GPCR光透射蛋白非正式地称为锥体色素。这些蛋白质的吸收最大值范围为350 nm至660 nm，在光吸收后，会经历有效的光漂白序列以产生活化的蛋白质。随后转霉素与活化蛋白的结合导致神经冲动和视力。在先前的NIH资助研究中进行的一个关键观察是，锥色在光激活过程中经历了反基因开关。这项研究的一个关键目的是探索反式开关机制是否也在红色和蓝色锥体色素中也活跃，如果是的，则表征分子细节。为了实现这一目标，我们将在从10K到环境的温度下使用振动和电子光谱，以陷阱并表征光漂白中间体。位置定向诱变将用于识别负责波长选择的关键残基和柜台开关的性质。从同源性研究中可以明显看出，许多红色锥体与自然界中的绿色，蓝色和紫外线和反式开关的实施不同。确实，红色锥体可能完全缺乏这种机械特征。这项研究的另一个目的是系统地确定紫外线，蓝色，绿色和红色锥体中波长选择的机制。尽管我们的研究确定了蓝色和紫外线中波长选择的关键特征，但仍有许多待理解。我们在这项研究中加入红锥是新的，我们对这个话题的热情部分依赖于我们相信红色锥有根本不同的。在初步研究的讨论中，我们有初步证据，即深红色锥体至少使用一种新机制进行波长选择，涉及操纵发色团环构象。独特的波长选择和明显不同（或缺失）的反式切换机制的组合使红色锥成为重要的目标。我们的研究将包括使用分子轨道理论来探测锥体色素中的结构功能关系，并计算结合发色团的光谱特性。我们将重新分配我们的MNDO-PSDCI代码，并改进界面，使这些程序对科学界更有用。和以前一样，我们将不收取感兴趣的研究人员提供这些程序。公共卫生相关性：越来越需要了解与锥形光感受器暴露相关的光漂白和恢复机制。因为这些细胞对于人类的光波视觉至关重要，所以重要的是要了解传递色素的相关光中的结构和功能关系。这项研究的项目目标可能有助于了解黄斑疾病，涉及锥细胞，锥体营养不良和其他眼部疾病，涉及视网膜感受器的损伤或功能减少。