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: 2911447
• 负责人: JANOS K LANYI
• 金额: $ 7.52万
• 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/2911447
• 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， 单个结合位点在两个膜表面之间交替， 依赖于产生能量的反应，而传输的离子是 通过特定路径进出该站点。光驱动的 质子泵和氯离子泵、细菌视紫红质和盐菌视紫红质 研究这种全球和局部机制的理想系统 过程相互作用以确保离子的单向运动 膜。尽管其细节特定于两种细菌 视紫红质，交替访问机制确定了以下原则： 可能适用于其他离子泵： a) 通过小型控制本地访问 活性位点的结构变化，b) 控制两种替代方案 通过局部静电效应的整体蛋白质构象，c) 通过改变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) 特异性控制 通过微妙。传输离子的氢键差异 它的结合位点，以及 e) 偶极子特性的重要参与 离子易位的所有过程中的结合水。研究 该提案中的策略是基于质子和质子的相似性 氯离子相互泵送，最近发现单个氨基 酸置换将一种的特异性改变为另一种。 这种重组视网膜蛋白将随着时间的推移进行检查- 可见光和红外分辨光谱、X 射线 晶体学和自旋标记探针，用于测定 a) 至 e) 的性质 为了区分与绑定相关的结构和过程 来自参与访问的离子的传输的传导 结合位点的改变。