| Project/Area Number |
15370066
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | Nagoya University |
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Principal Investigator |
KOUYAMA Tsutomu Nagoya University, Graduate School of Science, Professor, 大学院・理学研究科, 教授 (30170210)
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| Co-Investigator(Kenkyū-buntansha) |
MURAKAMI Midori Nagoya University, Graduate School of Science, Assistant Professor, 大学院・理学研究科, 助手 (20324387)
IHARA Kunio Nagoya University, Center for Gene Research, Assistant Professor, 遺伝子実験施設, 助手 (90223297)
ADACHI Shin-ichi Nagoya University, High Energy Accelerator Research Organization, Institute of Materials Structure Science, Associate Professor, 物質構造科学研究所, 助教授 (60260220)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥9,000,000 (Direct Cost: ¥9,000,000)
Fiscal Year 2004: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2003: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Biological Membrane / Membrane Protein / Bacteriorhodopsin / Rhodopsin / Archaerhodopsin / Halorhodopsin / X-ray Crystallography / Crystallization / X線結晶構造解析 / 膜蛋白質の結晶化 / 脂質-蛋白質間相互作用 / 反応中間体 / 生体膜 / シンクロトロン放射光 |
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| Research Abstract |
Bacteriorhodopsin, a transmembrane protein found in halobacterium halobium, functions as a light-driven proton pump. It is composed of 7 transmembrane helices and contains one molecule of retinal. This protein has been extensively studied by various biophysical techniques and its structure and function has been elucidated in detail. Structural analysis of the reaction intermediates is indispensable for better understanding of the proton pumping mechanism and determination of their structures at high resolution has been desired. Our group has developed a novel crystallization technique, so called the membrane fusion method, by which a three-dimensional crystal of bacteriorhodopsin containing native lipids can be prepared. By reducing the possible effect of X-radiation damages, we have succeeded in increasing the resolution of structural determination to such a level that water molecules within the protein can be visualized. In this project, we carried out a crystallographic analysis of the L intermediate of bacteriorhodopsin. It is found that formation of this intermediate accompanies the following structural changes : 1)amino-acid residues (Leu93 and Trp182) contacting the C13 methyl of retinal undergo significant structural changes (rotation and/or displacement of their side chains) ; 2)a water molecule that initially interacts with the retinal Schiff base moves to a micro-cavity that is created by rotation of the side chain of Leu93. Furthermore, we carried out X-ray crystallographic analysis of archaerhodopsin, a protein analogous to bacteriorhodopsin. As compared to bacteriorhodopsin, the proton release channel is more opened in archaerhodopsin. In addition, we crystallized squid rhodopsin and collected a low-resolution diffraction data.
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