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: 6195728
• 负责人: JANOS K LANYI
• 金额: $ 35.32万
• 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 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6195728
• 关键词: X ray crystallography; bacteriorhodopsins; chemical binding; chloride channels; chloride ion; conformation; hydrogen bond; hydrogen transport; infrared spectrometry; ion transport; membrane transport proteins; photochemistry; protein isoforms; protein structure function; site directed mutagenesis; time resolved data

Bacteriorhodopsin and halorhodopsin are the simplest ion pumps, and prototypes of the ubiquitous seven-transmembrane-helical proteins. We have made unusual progress in the past years and now propose to test and extend the resulting detailed step-by-step hypothesis for the mechanism of proton transport. It includes not only the proton transfer steps in the protein but also the thermodynamic and structural rationales for the unidirectionality and the vectoriality of the ion translocation. All aspects of this comprehensive hypothesis are now open to critical examination, and in the proposed work we will pay particular attention to the numerous mutant phenotypes not predicted by its present version. We will continue to use our present approach of combining sitespecific mutagenesis, time-resolved spectroscopy, and high-resolution protein x-ray crystallography to investigate i) structural questions at the proton release step, ii) how the pKs of dissociable groups are modulated, iii) the nature and causes of conformational coupling, iv) the mechanism of proton transport in the absence of asp-85 and asp-96, and v) the lessons to be learned from halorhodopsin and the D85T bacteriorhodopsin mutant, that both transport chloride ions and in the opposite direction from protons. The goal of this proposal is to establish, finally, a full and explicit model for the molecular mechanism of this kind of ion pump.

细菌紫红素和卤代紫红质是最简单的离子泵，并且 无处不在的七跨膜螺旋蛋白的原型。我们做了 在过去的几年中，异常进步，现在建议测试和扩展 质子机理的详细逐步假设 运输。它不仅包括蛋白质中的质子转移步骤，还包括 也是单向性的热力学和结构性理由和 离子易位的矢量性。这个全面的所有方面 假设现在可以接受批判性检查，在拟议的工作中，我们 将特别注意未预测的众多突变表型 通过目前的版本。我们将继续使用我们目前的方法 结合位置诱变，时间分辨光谱和 高分辨率蛋白X射线晶体学研究i）结构 质子发布步骤中的问题，ii）可分离组的PK是如何 调制，iii）构象耦合的性质和原因，iv） 在没有ASP-85和ASP-96的情况下，质子转运的机制，V） 要从甲霍顿蛋白和D85T细菌紫红素突变体中学到的课程， 均转运氯离子和与质子相反的方向。 该建议的目的是建立一个完整而明确的模型 用于这种离子泵的分子机制。