Role of Water Molecules in Proton Transfer in Bacteriorhodopsin

水分子在细菌视紫红质质子转移中的作用

基本信息

批准号：
07839003
负责人：
KANDORI Hideki
金额：
$ 1.47万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07839003/
关键词：
retinal protein bacteriorhodopsin water preton transfer infrared hydrogen-bonding dynamics rhodopsin

项目摘要

This research project aims at revealing the correlation between water structural changes in bacteriorhodopsin (bR) and its function, proton pumping. Fourier-transform infrared (FTIR) spectroscopy of mutant or isotope-labeled bR provided the following results.(1) We constructed the IR measuring system to obtain "noise-free" difference spectra between bR and its intermediates. In addition, time-resolved FTIR,polarized FTIR,and detection of protein-protein interaction by FTIR are now possibly applied to retinal proteins, providing much more information on their structural changes.(2) Location of water molecules in bR were examined by combination of bR mutants and FTIR.We have assigned the location of four water molecules, which are all present along the proton channel.(3) A water molecule whose O-H stretching vibration is located at 3643 cm^<-1> changes H-bonding upon formation of the L-intermediate. We found that the water structural change is essential in the proton transfer from the retinal Schiff base to Asp85.(4) We indentified Glu204 to be the proton release group. In addition, FTIR spectroscopy revealed hydrogen-bonding network between Asp85 and Glu204, including a water molecule in this region.(5) We found that single amino acid substitution converts proton pumping bR to the chloride pump like halorhodopsin (hR). It is likely that both bR and hR share the common mechanism of ion-pumping and only a single amino acid determines the pump property.

该研究项目的目的是揭示细菌紫红素（BR）的水结构变化及其功能，质子泵送之间的相关性。突变体或同位素标记的BR的傅立叶转换红外（FTIR）光谱提供了以下结果。（1）我们构建了IR测量系统，以获得BR及其中间体之间的“无噪声”差异光谱。 In addition, time-resolved FTIR,polarized FTIR,and detection of protein-protein interaction by FTIR are now possibly applied to retinal proteins, providing much more information on their structural changes.(2) Location of water molecules in bR were examined by combination of bR mutants and FTIR.We have assigned the location of four water molecules, which are all present along the proton channel.(3) A water molecule whose O-H拉伸振动位于3643 cm^<-1>形成L-Intermediate时变化H键。我们发现，水结构变化在质子从视网膜席夫碱基到ASP85的转移中至关重要。（4）我们将GLU204置为质子释放组。此外，FTIR光谱揭示了ASP85和GLU204之间的氢键网络，包括该区域的水分子。（5）我们发现，单个氨基酸替代物将质子泵送BR转换为氯化物泵，如甲莫陶正金（HR）。 BR和HR可能共享离子泵化的共同机制，并且只有单个氨基酸决定泵的性质。