Takakado Akira, Nakasone Yusuke, Terazima Masahide
Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Phys Chem Chem Phys. 2017 Sep 20;19(36):24855-24865. doi: 10.1039/c7cp03686h.
EL222 is a blue light sensor protein consisting of a light-oxygen-voltage (LOV) domain (EL-LOV domain) at the N-terminus and a helix-turn-helix DNA-binding domain at the C-terminus. EL222 acts as a light dependent transcriptional factor. The photochemical reactions of EL222 and the light sensing properties of the LOV domain were investigated. Concentration dependent experiments revealed that the EL-LOV domain is in equilibrium between the dimer and the monomer in the dark state, and the main photoreaction is the dimerization reaction between a monomer in the ground state and that in the excited state. The equilibrium constant and the intrinsic rate constants of dimerization were determined. EL222 was found to also exhibit photoinduced dimerization even in the absence of target DNA, although the yield of the reaction was low (∼0.08 compared with that of the EL-LOV domain). This observation suggests that there are inhomogeneous conformations, open and closed types, of EL222 in solution.
EL222是一种蓝光传感器蛋白，其N端由一个光-氧-电压（LOV）结构域（EL-LOV结构域）组成，C端有一个螺旋-转角-螺旋DNA结合结构域。EL222作为一种光依赖性转录因子发挥作用。对EL222的光化学反应和LOV结构域的光传感特性进行了研究。浓度依赖性实验表明，EL-LOV结构域在黑暗状态下处于二聚体和单体的平衡状态，主要光反应是基态单体与激发态单体之间的二聚化反应。测定了二聚化的平衡常数和固有速率常数。发现即使在没有靶DNA的情况下，EL222也会发生光诱导二聚化，尽管反应产率较低（与EL-LOV结构域相比约为0.08）。这一观察结果表明，溶液中的EL222存在开放型和封闭型等不均匀构象。
