Molecular models predict light-induced glutamine tautomerization in BLUF photoreceptors
Molecular models predict light-induced glutamine tautomerization in BLUF photoreceptors
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DOI：
10.1529/biophysj.107.124172
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发表时间：
2008-05-15
影响因子：
3.4
通讯作者：
Nemukhin, Alexander V.
中科院分区：
文献类型：
--
作者：
Domratcheva, Tatiana;Grigorenko, Bella L.;Nemukhin, Alexander V.
最近发现的含有BLUF(利用FAD的蓝光传感器)结构域的光感受器蛋白在细菌和真球藻中介导了对蓝光的生理反应。在BLUF结构域，蓝光激活黄素发色团，产生一种信号状态，其特征是类似于10 nm的红移吸收。我们在晶体结构和量子力学模拟的基础上，建立了球状红杆菌APPA蛋白BLUF结构域的暗态和光态的分子模型。根据这些模型，黄素对光子的吸收导致与黄素辅因子相互作用的谷氨酰胺侧链发生互变异构化和180度旋转。这种化学物质莫迪。谷氨酰胺残基的阳离子导致光感受器结构域核心的氢键网络的变化，这在许多光谱实验中都能观察到。计算得到的暗和光态的电子跃迁能和振动频率与在光周期中观察到的光学和红外光谱变化相一致。光诱导氨基酸残基的异构化而不是生色团的异构化代表了以前在光感受器中没有描述过的特征。
The recently discovered photoreceptor proteins containing BLUF (sensor of blue light using FAD) domains mediate physiological responses to blue light in bacteria and euglena. In BLUF domains, blue light activates the flavin chromophore yielding a signaling state characterized by a similar to 10 nm red-shifted absorption. We developed molecular models for the dark and light states of the BLUF domain of the Rhodobacter sphaeroides AppA protein, which are based on the crystal structures and quantum-mechanical simulations. According to these models, photon absorption by the flavin results in a tautomerization and 180 degrees rotation of the Gln side chain that interacts with the flavin cofactor. This chemical modi. cation of the Gln residue induces alterations in the hydrogen bond network in the core of the photoreceptor domain, which were observed in numerous spectroscopic experiments. The calculated electronic transition energies and vibrational frequencies of the proposed dark and light states are consistent with the optical and IR spectral changes observed during the photocycle. Light-induced isomerization of an amino acid residue instead of a chromophore represents a feature that has not been described previously in photoreceptors.