LIGHT DRIVEN ION TRANSPORT IN BACTERIAL RHODOPSINS

细菌视紫红质中的光驱动离子传输

• 批准号: 2734438
• 负责人: JANOS K LANYI
• 金额: $ 26.38万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 1981
• 资助国家: 美国
• 起止时间: 1981-07-01 至 2000-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2734438
• 关键词: X ray crystallography; active sites; bacteriorhodopsins; biophysics; chemical binding; chloride channels; dielectric property; dipole moment; hydrogen bond; infrared spectrometry; ion transport; molecular site; recombinant proteins; visible light; water

In the currently discussed mechanism for many ion pumps, the access of a single binding site alternates between the two membrane surfaces, dependent on an energy-yielding reaction, while the transported ion is conducted to and from this site by specific pathways. The light-driven proton and chloride ion pumps, bacteriorhodopsin and halorhodopsin, are ideal systems to study the mechanism in which such global and local processes interact to ensure the unidirectional movement of the ion across the membrane. Although its details are specific to the two bacterial rhodopsins, the alternating access mechanism identifies principles that may apply to other ion pumps: a) control of local access through small structural changes at the active site, b) control of two alternative global protein conformations through local electrostatic effects, c) control of binding affinity and internal ion transfer through changing dielectric environments in proteins domains, d) control of specificity through subtle. differences in hydrogen bonding of the transported ion at its binding site, and e) essential involvement of the dipole properties of bound water in all processes of the ion translocation. The research strategy in this proposal is based on the similarity of the proton and chloride pumps to one another, and the recent finding that a single amino acid replacement changed the specificity of one into the other. Recombinant retinal proteins of this kind will be examined with time- resolved spectroscopy in the visible and the infrared, x-ray crystallography, and spin-label probes for properties a) through e) in order to distinguish structures and processes relevant to the binding and conduction of the transported ions from those involved in the access change of the binding sites.

在当前讨论的许多离子泵的机制中，访问 两个膜表面之间的单个结合位点交替， 取决于能量赋予反应，而运输的离子为 通过特定途径往返于该站点。轻驱动 质子和氯离子泵，细菌淡淡蛋白质和乙酰胺蛋白是 研究这种全球和本地的机制的理想系统 过程相互作用以确保离子在 膜。虽然其细节特定于两个细菌 Rhodopsins，交替的访问机制确定了原则 可能适用于其他离子泵：a）通过小型控制本地访问 主动部位的结构变化，b）控制两个替代方案 通过局部静电效应，全球蛋白质构象，c） 通过更改控制结合亲和力和内部离子转移 蛋白质结构域中的介电环境，d）控制特异性 通过微妙。运输离子在氢键上的差异 它的结合位点，以及e）偶极特性的必要参与 在离子易位的所有过程中结合水。研究 该提案中的策略基于质子的相似性和 氯化物泵彼此，最近发现一个氨基 酸的替代品将一个变成另一个的特异性。 这种重组的视网膜蛋白将通过时间检查 可见的和红外X射线中的分辨光谱法 晶体学和特性的自旋标签探针a）通过e） 为了区分与结合和结构相关的结构和过程 从参与进入的人传导运输离子 更改结合位点。