Stability of Dimer and Domain-Domain Interaction of Arabidopsis Phototropin 1 LOV2
Stability of Dimer and Domain-Domain Interaction of Arabidopsis Phototropin 1 LOV2
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DOI：
10.1016/j.jmb.2008.08.074
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发表时间：
2008-11-21
影响因子：
5.6
通讯作者：
Terazima, Masahide
中科院分区：
文献类型：
--
作者：
Nakasone, Yusuke;Eitoku, Takeshi;Terazima, Masahide
没有连接子的拟南芥趋光素 1 光氧电压 2 (phot1LOV2) 域光激发后的瞬态光栅信号对温度非常敏感。特别是，扩散信号随着温度的升高而急剧增加。该信号一致地通过光诱导解离和缔合反应的叠加来解释。这一观察表明在黑暗中 phot1LOV2 结构域的单体和二聚体形式之间存在平衡。通过凝胶色谱技术确认平衡。根据二聚体的分数计算不同温度下的平衡常数，并测定稳定化焓和熵。有趣的是，phot1LOV2 与连接体（phot1LOV2-linker）（以单体形式存在）的瞬态光栅信号也与温度相关。扩散信号强度随着温度的升高而降低。因为扩散信号反映了光激发时连接体的构象变化，这种温度依赖性表明 phot1LOV2 连接体有两种形式。一种形式在光激发时表现出构象变化，而另一种形式则没有变化。这两种形式在光谱上无法区分。这些物种的比例取决于温度。考虑到 phot1LOV2 结构域的单体-二聚体平衡，我们建议非反应形式拥有与 LOV2 结构域分离的接头区域。由于连接子区域与 LOV2 结构域的解离是 phot1LOV2 连接子构象变化诱导生物活性的关键步骤，因此我们提出向光素可以发挥温度传感器的作用。 (C) 2008 Elsevier Ltd. 保留所有权利。
Transient grating signals after photoexcitation of Arabidopsis phototropin 1 light-oxygen-voltage 2 (phot1LOV2) domain without the linker were found to be very sensitive to temperature. In particular, the diffusion signal drastically increased with rising temperature. The signal was consistently explained by the superposition of the photo-induced dissociation and association reactions. This observation indicated the presence of an equilibrium between the monomer and dimer forms of the phot1LOV2 domain in the dark. The equilibrium was confirmed by a gel chromatographic technique. The equilibrium constants at various temperatures were calculated from the fraction of the dimer, and the stabilization enthalpy and entropy were determined. Interestingly, the transient grating signal of phot1LOV2 with the linker (phot1LOV2-linker), which exists as the monomer form, was also temperature dependent; the diffusion signal intensity decreased with increasing temperature. Because the diffusion signal reflects a conformation change of the linker upon photoexcitation, this temperature dependence indicated that there were two forms of the phot1LOV2-linker. One form exhibited a conformational change upon photoexcitation whereas the other form showed no change. These two forms are not distinguishable spectroscopically. The fraction of these species depended on the temperature. Considering the monomer-dimer equilibrium of the phot1LOV2 domain, we suggest that the nonreactive form possesses the linker region that is dissociated from the LOV2 domain. Because the dissociation of the linker region from the LOV2 domain is a key step for the conformation change of the phot1LOV2-linker to induce biological activity, we proposed that the phototropins could have a role as a temperature sensor. (C) 2008 Elsevier Ltd. All rights reserved.