Molecular Mechanism of Light-Induced Conformational Switching of the LOV Domain in Aureochrome-1
Molecular Mechanism of Light-Induced Conformational Switching of the LOV Domain in Aureochrome-1
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DOI：
10.1021/acs.biochem.0c00271
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发表时间：
2020-07-21
期刊：
影响因子：
2.9
通讯作者：
Hisatomi, Osamu
中科院分区：
文献类型：
--
作者：
Kobayashi, Itsuki;Nakajima, Hiroto;Hisatomi, Osamu
光氧电压敏感（LOV）结构域广泛存在于植物、藻类、真菌和细菌的感光蛋白中。LOV结构域的结构研究表明，苯丙氨酸和谷氨酰胺残基位于附近的发色团进行光照后的构象变化，然而，与激活的效应域的分子机制仍有待阐明。光拉链（Photozipper，PZ）蛋白是一种N-末端截短的金色素-1，包含LOV结构域和碱性亮氨酸拉链结构域。蓝光（BL）诱导PZ二聚化，随后增加其对靶DNA的亲和力。在本研究中，我们制备了具有F298和Q317取代的PZ突变体，并在黑暗和光照状态下进行定量分析。Q317的取代显着降低了光诱导的变化PZ亲和力的目标DNA，特别是在黑暗状态下观察到的高亲和力的情况下。在光照下，所有PZ突变体显示出对靶序列的亲和力增加，这证明了与每个PZ突变体的二聚体分数的明确相关性。这些结果表明，存在一个构象平衡，它的移动由发色团和蛋白质部分之间的协同相互作用可能使BL调节开关的aureochrome-1。
Light oxygen voltage-sensing (LOV) domains are widely found in photoreceptor proteins of plants, algae, fungi, and bacteria. Structural studies of LOV domains suggest that Phe and Gln residues located in the proximity of the chromophore undergo conformational changes upon illumination; however, the molecular mechanism associated with activation of the effector domain remains to be elucidated. Photozipper (PZ) protein is an N-terminally truncated aureochrome-1 comprising a LOV domain and a basic leucine zipper domain. Blue light (BL) induces PZ dimerization and subsequently increases its affinity for target DNA. In this study, we prepared PZ mutants with substitutions of F298 and Q317 and performed quantitative analyses in dark and light states. Substitutions of Q317 significantly reduced the light-induced changes in PZ affinity for the target DNA, especially in the case of the high affinities observed in the dark state. Upon illumination, all PZ mutants showed increased affinity for the target sequence, which demonstrated a clear correlation with the dimer fraction of each PZ mutant. These results suggest the existence of a conformational equilibrium and that its shift by a synergistic interaction between the chromophore and protein moiety probably enables BL-regulated switching of aureochrome-1.