High thermal stability of oligomeric assemblies of Thermophilic rhodopsin in a lipid environment.
High thermal stability of oligomeric assemblies of Thermophilic rhodopsin in a lipid environment.
复制标题
脂质环境中嗜热视紫红质寡聚体的高热稳定性。
DOI：
10.1021/acs.jpcb.8b04894
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发表时间：
2018
期刊：
影响因子：
3.3
通讯作者：
and Yasuhisa Mizutani
中科院分区：
文献类型：
--
作者：
Tomomi Shionoya;Misao Mizuno;Takashi Tsukamoto;Kento Ikeda;Hayato Seki;Keiichi Kojima;Mikihiro Shibata;Izuru Kawamura;Yuki Sudo;and Yasuhisa Mizutani
嗜热视紫红质（thermophilic rhodopsin，TR）是极端嗜热菌Thermus thermophilusJL-18产生的一种光驱动质子泵。先前对用去污剂溶解的TR的研究表明，该蛋白质表现出高热稳定性，并在室温下形成三聚体，但在生理温度（75 ° C）下孵育时不可逆地解离成单体。在本研究中，我们使用共振拉曼（RR）光谱，固态核磁共振光谱和高速原子力显微镜分析TR在脂质环境中的低聚体结构。所获得的光谱和显微镜图像表明，TR采用五聚体形式在脂质环境中，并且该组件在生理温度下是稳定的，与溶解状态下的蛋白质的行为相反。这些结果表明，TR的低聚组装体的热稳定性在脂质环境中比在洗涤剂胶束中更高。观察到的RR光谱还表明，视网膜发色团是强烈的氢键内部水分子通过质子化的席夫碱，这是质子泵视紫红质的特性。所获得的数据有力地表明，TR功能的五聚体形式在生理温度下在极端嗜热T。嗜热菌JL-18。我们利用了高的热稳定性的单体形式的溶解TR，并在这里报告的第一RR光谱的单体形式的微生物视紫红质。所观察到的RR光谱表明，TR的单体化改变了发色团结构：多烯链的键交替和质子化席夫碱的氢键强度发生了变化。本研究揭示了TR的低聚体组装体在脂质环境中的高的热稳定性，并建议使用TR嵌入脂质膜阐明其功能机制的重要性。
Thermophilic rhodopsin (TR) is a light-driven proton pump from the extreme thermophileThermus thermophilusJL-18. Previous studies on TR solubilized with detergent showed that the protein exhibits high thermal stability and forms a trimer at room temperature but irreversibly dissociates into monomers when incubated at physiological temperature (75 °C). In the present study, we used resonance Raman (RR) spectroscopy, solid-state NMR spectroscopy, and high-speed atomic force microscopy to analyze the oligomeric structure of TR in a lipid environment. The obtained spectra and microscopic images demonstrate that TR adopts a pentameric form in a lipid environment and that this assembly is stable at the physiological temperature, in contrast to the behavior of the protein in the solubilized state. These results indicate that the thermal stability of the oligomeric assembly of TR is higher in a lipid environment than in detergent micelles. The observed RR spectra also showed that the retinal chromophore is strongly hydrogen bonded to an internal water molecule via a protonated Schiff base, which is characteristic of proton-pumping rhodopsins. The obtained data strongly suggest that TR functions in the pentameric form at physiological temperature in the extreme thermophileT. thermophilusJL-18. We utilized the high thermal stability of the monomeric form of solubilized TR and here report the first RR spectra of the monomeric form of a microbial rhodopsin. The observed RR spectra revealed that the monomerization of TR alters the chromophore structure: there are changes in the bond alternation of the polyene chain and in the hydrogen-bond strength of the protonated Schiff base. The present study revealed the high thermal stability of oligomeric assemblies of TR in the lipid environment and suggested the importance of using TR embedded in lipid membrane for elucidation of its functional mechanism.