Blue Light-Induced Conformational Changes in a Light-Regulated Transcription Factor, Aureochrome-1
Blue Light-Induced Conformational Changes in a Light-Regulated Transcription Factor, Aureochrome-1
复制标题
DOI：
10.1093/pcp/pcs160
复制
发表时间：
2013-01-01
影响因子：
4.9
通讯作者：
Kataoka, Hironao
中科院分区：
文献类型：
--
作者：
Hisatomi, Osamu;Takeuchi, Ken;Kataoka, Hironao
Aureochrome-1（AUREO 1）是介导冷灯心草（Vaucheria frigida）分支反应的蓝光（BL）受体。AUREO 1在N端具有碱性亮氨酸拉链（bZIP）结构域，在C端区域具有光氧电压敏感（LOV）结构域，并且已被认为是光调节转录因子。为了了解AUREO 1的分子机制，我们制备了三种重组蛋白：全长AUREO 1（FL），含有bZIP和LOV的N-末端截短构建体（ZL）和LOV-only（LOV）构建体。构建体在黑暗状态下显示出相同的吸收和荧光光谱，并且经历了如先前在BL激发时在LOV结构域中观察到的特征性循环反应。FL和ZL以序列特异性方式与DNA结合。BL似乎诱导LOV结构域的α-螺旋结构向β-折叠结构的转变，但不改变该结构域的流体动力学半径（R-H）。ZL可能通过bZIP中的二硫键以及bZIP和LOV之间的接头区域形成二聚体。BL诱导ZL的R-H增加约5%，但其二级结构不变。这些结果支持BL诱导的LOV结构域的变化可能导致bZIP和/或二聚体ZL分子的接头的构象变化的模式。由于在FL构建体中也观察到R-H增加了5%，因此BL可能会诱导与ZL观察到的相似的整体构象变化，并且FL二聚体的形成可能有助于DNA结合。
Aureochrome-1 (AUREO1) is a blue light (BL) receptor that mediates the branching response in the stramenopile alga, Vaucheria frigida. AUREO1 harbors a basic leucine zipper (bZIP) domain at the N-terminus and a light-oxygen-voltage-sensing (LOV) domain within the C-terminal region, and has been suggested to function as a light-regulated transcription factor. To understand the molecular mechanism of AUREO1, we have prepared three recombinant proteins: a full-length AUREO1 (FL), an N-terminal truncated construct containing bZIP and LOV (ZL) and a LOV-only (LOV) construct. The constructs showed the same absorption and fluorescent spectra in the dark state and underwent the characteristic cyclic reaction as previously observed in LOV domains upon BL excitation. FL and ZL bound to DNA in a sequence-specific manner. BL appeared to induce a shift of the alpha-helical structure of the LOV domain to a beta-sheet structure, but did not alter the hydrodynamic radius (R-H) of this domain. ZL formed a dimer possibly through disulfide linkages in the bZIP and the linker region between bZIP and LOV. BL induced an approximately 5% increase in the R-H of ZL, although its secondary structure was unchanged. These results support a schema where BL-induced changes in the LOV domain may cause conformational changes in the bZIP and/or the linker of a dimeric ZL molecule. Since a 5% increase of the R-H was also observed with the FL construct, BL may induce global conformational changes similar to those observed for ZL, and formation of the FL dimer may facilitate DNA binding.