Institute of Complex Systems, ICS-6: Structural Biochemistry, Forschungszentrum Jülich, 52425 Jülich, Germany.
Institut für Molekulare Enzymtechnologie, Heinrich-Heine-Universität Düsseldorf, Forschungszentrum Jülich, D-52426 Jülich, Germany.
Sci Rep. 2017 Feb 17;7:42971. doi: 10.1038/srep42971.
Unique features of Light-Oxygen-Voltage (LOV) proteins like relatively small size (~12-19 kDa), inherent modularity, highly-tunable photocycle and oxygen-independent fluorescence have lately been exploited for the generation of optical tools. Structures of LOV domains reported so far contain a flavin chromophore per protein molecule. Here we report two new findings on the short LOV protein W619_1-LOV from Pseudomonas putida. First, the apo-state crystal structure of W619_1-LOV at 2.5 Å resolution reveals conformational rearrangements in the secondary structure elements lining the chromophore pocket including elongation of the Fα helix, shortening of the Eα-Fα loop and partial unfolding of the Eα helix. Second, the apo W619_1-LOV protein binds both natural and structurally modified flavin chromophores. Remarkably different photophysical and photochemical properties of W619_1-LOV bound to 7-methyl-8-chloro-riboflavin (8-Cl-RF) and lumichrome imply application of these variants as novel optical tools as they offer advantages such as no adduct state formation, and a broader choice of wavelengths for in vitro studies.
独特的光氧电压（LOV）蛋白的特点，如相对较小的尺寸（约 12-19 kDa）、固有的模块化、高度可调的光循环和与氧无关的荧光，最近已被用于开发光学工具。迄今为止报道的 LOV 结构域包含每个蛋白质分子的一个黄素发色团。在这里，我们报告了来自恶臭假单胞菌的短 LOV 蛋白 W619_1-LOV 的两个新发现。首先，在 2.5 Å分辨率下，W619_1-LOV 的无配体状态晶体结构揭示了围绕发色团口袋的二级结构元件的构象重排，包括 Fα 螺旋的伸长、Eα-Fα 环的缩短和 Eα 螺旋的部分展开。其次，无配体 W619_1-LOV 蛋白结合天然和结构修饰的黄素发色团。W619_1-LOV 与 7-甲基-8-氯-核黄素（8-Cl-RF）和光黄素结合的明显不同的光物理和光化学性质表明，这些变体可作为新型光学工具应用，因为它们具有形成加合物状态的优势，以及更广泛的体外研究波长选择。
