Light-induced hydrogen bonding pattern and driving force of electron transfer in AppA BLUF domain photoreceptor
Light-induced hydrogen bonding pattern and driving force of electron transfer in AppA BLUF domain photoreceptor
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DOI：
10.1074/jbc.m803864200
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发表时间：
2008-11-07
影响因子：
4.8
通讯作者：
Ishikita, Hiroshi
中科院分区：
文献类型：
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作者：
Ishikita, Hiroshi
来自球形红杆菌的 AppA BLUF（使用 FAD 进行蓝光传感）结构域充当蓝光传感光感受器。 Tyr-21 和黄素之间的电荷分离过程通过将暗态构象转变为亮态构象，在光信号状态中发挥着重要作用。通过求解线性化泊松-玻尔兹曼方程，我计算了 Tyr-21、黄素和氧化还原活性 Trp-104 的 E(m)，并揭示了电子转移 (ET) 驱动能量。将蛋白质构象从暗态转换为亮态的 Gln-63 侧链的旋转导致 Tyr-21 的 E(m) 降低 150 mV，导致亮态构象中的 ET 驱动能量显着增大。黄素阴离子质子化的 pK(α) 值在暗态和亮态晶体结构中基本相同。与通过 Tyr-21 的 ET 相比，W.(+) 态的形成导致仅生成暗态构象（即使初始构象处于亮态）；这可以解释为什么Trp-104介导的ET使光感应产量失活以及为什么W104A突变体的活性与光适应的天然BLUF的活性相似。
The AppA BLUF (blue light sensing using FAD) domain from Rhodobacter sphaeroides serves as a blue light-sensing photoreceptor. The charge separation process between Tyr-21 and flavin plays an important role in the light signaling state by transforming the dark state conformation to the light state one. By solving the linearized Poisson-Boltzmann equation, I calculated E(m) for Tyr-21, flavin, and redox-active Trp-104 and revealed the electron transfer (ET) driving energy. Rotation of the Gln-63 side chain that converts protein conformation from the dark state to the light state is responsible for the decrease of 150 mV in E(m) for Tyr-21, leading to the significantly larger ET driving energy in the light state conformation. The pK(alpha) values of protonation for flavin anions are essentially the same in both dark and light state crystal structures. In contrast to the ET via Tyr-21, formation of the W.(+) state results in generation of only the dark state conformation (even if the initial conformation is in the light state); this could explain why Trp-104-mediated ET deactivates the light-sensing yield and why the activity of W104A mutant is similar to that of the light-adapted native BLUF.