Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Biochemistry. 2010 Mar 16;49(10):2288-96. doi: 10.1021/bi902121z.
The spectrally silent photoreaction of a blue light sensor protein YcgF, composed of the N-terminal BLUF domain and the C-terminal EAL domain, was investigated by the time-resolved transient grating method. Comparing photoinduced reactions of full-length YcgF with that of the BLUF-linker construct, it was found that a major conformation change after photoinduced dimerization is predominantly localized on the EAL domain. Furthermore, the photoinduced conformational change displayed significant temperature dependence. This result is explained by an equilibrium of reactive and nonreactive YcgF species, with the population of photoreactive species decreasing as the temperature is lowered in the dark state. We consider that the dimer form is the nonreactive species and it is the dominant species at lower temperatures. The temperature sensitivity of the photoreaction of YcgF suggests that this protein could have a biological function as a temperature sensor as well as behaving as a light sensor.
采用时间分辨瞬态光栅法研究了由 N 端 BLUF 结构域和 C 端 EAL 结构域组成的蓝光传感器蛋白 YcgF 的光谱静默光反应。通过比较全长 YcgF 的光诱导反应与 BLUF 连接子构建体的光诱导反应，发现光诱导二聚化后的主要构象变化主要定位于 EAL 结构域。此外，光诱导构象变化表现出显著的温度依赖性。这一结果可以通过活性和非活性 YcgF 物种的平衡来解释，在黑暗状态下，随着温度降低，光反应性物种的数量减少。我们认为二聚体形式是非活性物种，并且在较低温度下它是主要的物种。YcgF 光反应的温度敏感性表明，该蛋白除了作为光传感器外，还可能具有作为温度传感器的生物学功能。
