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: 6767586
• 负责人: JANOS K LANYI
• 金额: $ 40.78万
• 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/6767586
• 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.

细菌视紫红质和盐视紫红质是最简单的离子泵