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Molecular mechanism of light-sensor proteins containing a flavin

含黄素的光传感器蛋白的分子机制

基本信息

批准号：
17370057
负责人：
KANDORI Hideki
金额：
$ 9.47万
依托单位：
Nagoya Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17370057/
关键词：
biophysics nano-bio biomolecule protein photo-switch flavin FTIR hydrogen bond

项目摘要

Phototropin is a blue-light sensor protein in plants, and LOV domain binds a flavin mononucleotide (FMN) as a chromophore. A photointermediate state, S390, is formed by light-induced adduct formation between FMN and a nearby cysteine, which triggers protein structural changes for kinase activation in phototropin. In this project, we aimed at revealing the molecular mechanism of light-signal transduction in LOV domains.By means of low-temperature FTIR spectroscopy, we revealed that the reactive cysteine is protonated in the triplet-excited state of the LOV2 domain of Adiantum phytochrome3 (phy3-LOV2) as well as its unphotolyzed state. Its hydrogen-bonding interaction is strengthened in the triplet-excited state, presumably with the FMN chromophore, and such strong interaction drives adduct formation in a microsecond timescale.Phototropin has two LOV domains called LOV1 and LOV2. Why does it have two domains? A transgenic study suggested that only LOV2 is necessary in the function of phototropin, whereas X-ray structures are surprisingly similar between LOV1 and LOV2 domains. We compared protein structural changes between the LOV1 and LOV2 domains of phy3 by means of UV-visible and FTIR spevctroscopy. We found that protein structural changes are much larger in LOV2 than in LOV1, which is consistent with their functional roles. We concluded that plants utilize a unique protein architecture (LOV domain) for different functions by regulating their protein structural changes. Regarding the protein structural changes, we previously observed temperature-dependent FTIR spectral changes in the amide-I vibrational region of peptide backbone for phy3-LOV2, suggesting the progressive structural changes in the protein moiety. Since FMN also possesses two C=O groups, we assigned C=O stretching vibrations of FMN and protein by using ^<13>C-labeling in this article. Consequently, temperature-dependent amide-I bands are unequivocally assigned by separating the chromophore bands.

趋光素是植物中的一种蓝光感受器蛋白，LOV结构域结合黄素单核苷酸(FMN)作为发色团。光中间状态S390是通过光诱导FMN与附近的半胱氨酸形成加合物而形成的，该加合物触发了蛋白质结构的变化，从而激活了趋光性激素中的激酶。本课题旨在揭示LOV结构域光信号转导的分子机制，通过低温傅立叶变换红外光谱分析，揭示了铁线藻类植物色素3(Phy3-LOV2)LOV2结构域的三重态激发态及其未光解状态下反应性半胱氨酸的质子化。它的氢键相互作用在三重激发态下被加强，可能是与FMN生色团，这种强烈的相互作用在微秒级驱动加合物的形成。Phototroin有两个LOV结构域，称为LOV1和LOV2。为什么它有两个域？一项转基因研究表明，只有LOV2对趋光素的功能是必需的，而LOV1和LOV2结构域的X射线结构令人惊讶地相似。我们用紫外-可见光谱和傅里叶变换红外光谱比较了Phy3的LOV1和LOV2结构域之间的蛋白质结构变化。我们发现LOV2的蛋白质结构变化比LOV1大得多，这与它们的功能作用是一致的。我们的结论是，植物通过调节其蛋白质结构的变化来利用独特的蛋白质结构域(LOV结构域)来实现不同的功能。在蛋白质结构的变化方面，我们先前观察到PHY3-LOV2多肽骨架的酰胺-I振动区的FTIR光谱随温度的变化，表明蛋白质部分的结构发生了渐进性变化。由于FMN也有两个C=O基团，本文用~(13)C-标记法对FMN和蛋白质的C=O伸缩振动进行了归属。因此，依赖于温度的酰胺-I带通过分离生色团带而被明确地指定。