Mechanism of signal transduction in photoreceptors

光感受器信号转导机制

• 批准号: 6599689
• 负责人: HARTMUT LUECKE
• 金额: $ 25.05万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-08-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6599689
• 关键词: X ray crystallography; conformation; cryoscience; crystallization; phosphorylation; photoactivation; photosynthetic bacteria; protein isoforms; protein protein interaction; protein structure function; rhodopsin; structural biology; visual photoreceptor; visual phototransduction; X ray crystallography; conformation; cryoscience; crystallization; phosphorylation; photoactivation; photosynthetic bacteria; protein isoforms; protein protein interaction; protein structure function; rhodopsin; structural biology; visual photoreceptor; visual phototransduction

DESCRIPTION (provided by applicant): Signal reception and signal transduction constitute fundamental processes by which living cells perceive and ultimately react to external stimuli such as light, chemicals (nutrients, toxins, hormones), heat and mechanical signals. Most signal receptors reside in the cytoplasmic membrane that separates the inside of a cell from the external medium. Primary receptors for light (photoreceptors) are the basis of all forms of vision where the energy from absorbed single photons is used to bring about a conformational change in the chromophore, usually the isomerization of a double bond within picoseconds. On a slower timescale, the surrounding protein and water matrix responds to the conformational change of the chromophore and ultimately results in conformational and electrostatic changes that are sensed by a transducer molecule. Microbial rhodopsins are a family of photoactive, seven-transmembrane helix, retinylidene proteins found in phylogenetically diverse microorganisms, including haloarchaea, proteobacteria, cyanobacteria, fungi, and algae. Sensory rhodopsins I and II (SRI and SRII) in haloarchaea, Chlamydomonas rhodopsins CsoA and CsoB, and Anabaena rhodopsin, are photosensory receptors, spectrally tuned throughout the visible spectrum to relay information to the cell regarding the intensity and color of light in the environment. SRI and SRII are sensors for phototaxis in Hatobacterium salinarum and related halophilic archaea. SRI mediates attractant motility responses to green-orange wavelengths used by the ion pumps BR and HR, while SRII mediates blue-light avoidance responses. The SRI and SRII proteins are subunits of multicomponent signaling complexes and relay signals by protein-protein interaction to integral membrane transducer proteins (HtrI and HtrII, respectively) that control a cytoplasmic phosphorylation pathway that modulates the cell's motility apparatus. In order to elucidate the basis of spectral tuning of the photoreceptor sensory rhodopsin (SRII) and to obtain a detailed structure-based mechanism of how light-induced conformational changes trigger signaling in its cognate transducer (HtrII) we will 1. Determine the structure of the single-site mutant R72A, a residue recently implicated in spectral tuning. 2, Determine the crystal structure of the photoreceptor in the long-lived (O) signaling state and identify the main signaling components by comparing it to the recently solved ground state structure. 3, Compare the crystal structure of the 9-TM helical SRII/HtrlI fusion construct in the off-state with that of the photoactivated signaling state, In order to determine the atomic structure and the photoactivation mechanism of the recently identified Anabaena photoreceptor and its soluble putative transducer we will 4. Determine the crystal structure of the soluble putative transducer, a 14-kDa protein on the same operon as the photoreceptor with no sequence homology to any known protein. 5. Determine the crystal structure of the primary Anabaena photoreceptor in the ground and signaling state. 6. Determine the structure of the complex of the Anabaena photoreceptor with its putative transducer.

描述（由申请人提供）：信号接收和信号转导构成了基本过程，通过这些过程，活细胞感知并最终对外部刺激作出反应，例如光，化学物质（营养素，毒素，激素），热和机械信号。大多数信号受体都位于将细胞内部与外部培养基分开的细胞质膜中。光（光感受器）的主要受体是所有形式的视力基础，其中使用吸收的单光子的能量来实现发色团的构象变化，通常是在picseconds中双键的异构化。在较慢的时间尺度上，周围的蛋白质和水基质对发色团的构象变化做出反应，并最终导致构象和静电变化，这些变化被传感器分子所感受到。微生物视紫红蛋白是光活性，七跨膜螺旋的家族，在系统发育多样的微生物中发现的视网膜基岛蛋白，包括卤藻，蛋白质细菌，蓝细菌，蓝细菌，真菌和藻类。 Haloarchaea，Chlamydomonas Rhodopsins CSOA和CSOB以及Anabaena Rhodopsin中的感觉视紫红蛋白I和II（SRI和SRII）是光感受体，在整个可见光频谱中进行了频谱调整，以将信息传递到环境中的强度和颜色的细胞中。 SRI和SRII是盐菌和相关的卤素古细菌中光的传感器。 SRI介导了对离子泵BR和HR使用的绿橙波长的吸引力运动响应，而SRII介导了蓝光避免反应。 SRI和SRII蛋白是蛋白质 - 蛋白质相互作用与整合性膜传感器蛋白（HTRI和HTRII）的多组分信号传导复合物和中继信号的亚基，可控制细胞质磷酸化途径，从而调节细胞的运动能力。为了阐明光感受器感觉视蛋白（SRII）的光谱调整的基础，并获得一种基于详细的结构机制，即如何在其同源传感器（HTRII）中触发构象变化触发信号传导，我们将1。确定单位突变R72A的结构，近期是残留的镜头。 2，确定长寿命（O）信号状态中光感受器的晶体结构，并通过将其与最近求解的基态结构进行比较来识别主信号分量。 3, Compare the crystal structure of the 9-TM helical SRII/HtrlI fusion construct in the off-state with that of the photoactivated signaling state, In order to determine the atomic structure and the photoactivation mechanism of the recently identified Anabaena photoreceptor and its soluble putative transducer we will 4. Determine the crystal structure of the soluble putative transducer, a 14-kDa protein on the same操纵子作为光感受器，与任何已知蛋白质无序性同源。 5。确定地面和信号传导状态中原代Anabaena光感受器的晶体结构。 6。确定Anabaena感光器与推定换能器的复合物的结构。