PHOTOSENSORY TRANSDUCTION IN HALOBACTERIA

盐细菌中的光感传导

• 批准号: 3302633
• 负责人: ROBERTO A. BOGOMOLNI
• 金额: $ 14.85万
• 依托单位: UNIVERSITY OF CALIFORNIA SANTA CRUZ
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-01 至 1995-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3302633
• 关键词: Archaea; Raman spectrometry; calcium; chemical kinetics; cilium /flagellum motility; conformation; flash photolysis; infrared spectrometry; light intensity; light scattering; lipid bilayer membrane; membrane activity; membrane reconstitution /synthesis; micelles; photoactivation; photoelectron spectrometry; photolysis; photostimulus; photosystem; polarimetry; protein purification; protein reconstitution; quantum chemistry; rhodopsin; stereochemistry; visual photoreceptor; visual phototransduction

Our long-term objective is to understand fundamental molecular mechanisms of photoreceptor activation and cellular signaling in halobacterial phototaxis. In archaebacteria retinal-chromoproteins function as light energy converters and light signal transducers. Bacteriorhodopsin (bR) and halorhodopsin (hR) are light-driven proton and chloride pumps respectively, and the sensory rhodopsins I and II (sR-I,sR-II) are phototaxis receptors. Cells are attracted by orange-red light and repelled by UV-blue light, actively seeking an environment optimal for light absorption by bR and hR. These pigments undergo cyclic photoreactions in the millisecond (bR and hR) to second (sR's) range. A UV-absorbing intermediate of the sR-I photocycle, S(373), accumulates in natural light and functions as an additional photoreceptor. Upon photoactivation S(373) converts back to sR-I generating in the process a repellent signal. This unique photochromic system, sR-I/S(373), provides this primitive organism with a simple, yet effective, color discrimination system. Our aims are to identify the "activated" photoreceptor state(s) involved in signal generation, to characterize the molecular changes associated with the processes, and to establish the chemical or physical nature of the signal(s). Specifically we will: 1) isolate and spectroscopically characterize the sR-I/(373) system. 2) investigate its photochemical reactions and associated structural changes in the native membrane and in purified pigment in detergent micelles and in lipid bilayers. 3) identify signal- generating photochemical reactions. For this we will investigate the effect of retinal analogue substitution, double flash excitation, and mutagenesis on photocycle and phototaxis kinetics. 4) investigate the signaling mechanism(s). We will study the effect of components known to be involved in the signal transduction system on the photocycle kinetics and on the rotational diffusion of the photoreceptors and their thermal intermediates in both normal strains and in our newly isolated mutants with altered phototaxis. Absorption and laser-flash spectroscopy in the UV-visible and IR ranges, photoselection spectroscopy, resonance Raman scattering and measurements of intramolecular charge displacements will be used to gain insight on structural changes associated with photoreceptor activation.

我们的长期目标是了解 光感受器激活和细胞信号传导的机制 嗜盐菌趋光性 在古细菌中，视网膜色素蛋白的功能是光能 转换器和光信号转换器。 细菌视紫红质（bR）和 盐视紫红质（hR）是光驱动质子和氯离子泵 感觉视紫红质I和II（sR-I，sR-II）分别是 趋光性受体 细胞被橙红色的光吸引， 排斥紫外线蓝光，积极寻求最佳环境， bR和hR的光吸收。这些色素经历循环 在毫秒（bR和hR）到秒（sR）范围内的光反应。 sR-I光循环的紫外吸收中间体S（373）积累 在自然光下，作为额外的感光器。 后 光活化S（373）转化回在该过程中产生的sR-I 一个令人厌恶的信号 这种独特的光致变色系统，sR-I/S（373）， 为这种原始生物提供了一种简单而有效的颜色 歧视制度。 我们的目标是确定“激活” 光感受器状态参与信号产生，以表征 与这些过程相关的分子变化，并建立 信号的化学或物理性质。 具体来说，我们将：1）分离和光谱表征 sR-I/（373）系统。2)研究其光化学反应， 天然膜和纯化膜中的相关结构变化 洗涤剂胶束和脂质双层中的颜料。3)识别信号- 产生光化学反应。 为此，我们将调查 视网膜类似物替代、双闪光激发和 光循环和趋光性动力学的诱变。4)探讨 信令机制。我们将研究已知成分的影响， 参与光循环动力学的信号转导系统 以及光感受器的旋转扩散和它们的热扩散 在正常菌株和我们新分离的突变体中的中间体 改变了趋光性 紫外-可见和红外范围内的吸收和激光闪光光谱， 光选择光谱、共振拉曼散射和测量 分子内电荷位移将用于深入了解 与感光细胞激活相关的结构变化。