MECHANISM OF CHLORIDE TRANSPORT BY HALORHODOPSIN

盐视紫红质的氯离子转运机制

• 批准号: 3277142
• 负责人: JANOS K LANYI
• 金额: $ 10.22万
• 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 1987-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3277142
• 关键词: Halobacteriaceae; bacteriorhodopsins; chemical structure function; crosslink; gel electrophoresis; liposomes; membrane activity; microorganism culture; mutant; photobiology; photochemistry; spectrometry

We will explore the mechanism by which halorhodopsin functions as a light-driven electrogenic chloride pump. This chloride-transport system, found in the cytoplasmic membrane of halobacteria, is a retinal pigment whose chromophore exhibits flash-induced absorbance changes dependent on the presence of chloride. Furthermore, chloride, as well as other anions, apparently influences the pK of the retinal Schiff's base. Studying these phenomena in more detail, and using specific labels to modify selected amino acid residues, we will describe the groups involved in the binding of chloride, the number of chloride-binding sites and their relationship to one another, and the role of protonation/deprotonation of groups in the chloride translocation. Special attention will be paid to the possibility that halorhodopsin contains a sulfhydryl group with an influence on the photochemistry of the pigment. Although the purified chromoprotein (apparent molecular weight 21 kDa) of halorhodopsin binds chloride, and shows the chloride-dependent effects observed with the intact system, we will search for and identify any other, so far unknown, components of halorhodopsin. In this study we expect to establish the basis for a first model of the molecular mechanism of how the photochemical changes are related to chloride translocation against an electrochemical gradient. Such a model should contribute to the understanding of ionic pumps in general.

我们将探索卤视紫红质作为一种 光驱生电式氯化物泵。这个氯化物运输系统， 在嗜盐细菌的细胞膜中发现了一种视网膜色素 其发色团表现出闪光诱导的吸光度变化，依赖于 氯化物的存在。此外，氯化物以及其他阴离子， 明显影响视网膜Schiff‘s底座的PK。研究这些 更详细的现象，并使用特定标签修改选定的 氨基酸残基，我们将描述参与结合的基团 氯，氯结合位点数及其与 以及基团的质子化/去质子化在 氯化物易位。我们将特别注意这种可能性。 卤视紫红质含有一个硫基，对 颜料的光化学。虽然纯化的染色质蛋白 (表观分子量21 kDa)卤视紫红质与氯化物结合，以及 显示了在完整系统中观察到的氯离子依赖效应，我们 将搜索并识别任何其他迄今未知的组件 卤视紫质。在这项研究中，我们希望为第一次 光化学变化的分子机制模型 与与电化学梯度相反的氯离子转移有关。 这样的模型应该有助于理解 将军。