Dynamics of conformational changes of Arabidopsis phototropin 1 LOV2 with the linker domain
Dynamics of conformational changes of Arabidopsis phototropin 1 LOV2 with the linker domain
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DOI：
10.1016/j.jmb.2006.12.074
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发表时间：
2007-03-23
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
利用时间分辨瞬变光栅(TG)和瞬变透镜(TrL)方法，从分子体积和分子扩散系数(D)变化的角度研究了拟南芥PHY1-LOV2与连接体(PHY1-LOV2-Linker)的构象变化。虽然吸收光谱的变化在几微秒内完成，但TG方法检测到的D值急剧下降，时间常数为1.0ms，从9.2(+/-0.4)×10(-11)m(2)/S下降到5.0(+/-0.3)x10(-11)m(2)/S。通过观察圆二色谱强度的恢复，证实了α螺旋的变化。TrL信号表明，分子体积随两个时间常数而减小：300u S和1.0ms。前者的时间常数与先前观察到的PHY1-LOV2(不含连接基)二聚体的光解反应速率相近，而后者与D-变化速率很好地吻合。考虑到LOV2二聚体解离反应的相似时间常数，我们用连接区从LOV2结构域(T-390(前)状态)的解离步骤来解释这些动力学。经过这一步骤后，蛋白质体积和D显著减小，寿命为1.0ms。D的降低表明蛋白质与水分子间的分子间相互作用增强。在这些观察的基础上，提出了连接子的两步展开机制。(C)2007爱思唯尔有限公司。保留所有权利。
Conformational changes of Arabidopsis phot1-LOV2 with the linker (phot1-LOV2-linker) were investigated from the viewpoint of the changes in molecular volume and molecular diffusion coefficient (D) by time-resolved transient grating (TG) and transient lens (TrL) methods. Although the absorption spectrum change completes within a few microseconds, the D-value detected by the TG method decreased drastically with a time constant of 1.0 ms from 9.2(+/- 0.4) x 10(-11) m(2)/S to 5.0(+/- 0.3) x 10(-11) m(2)/S. This time-dependent D was interpreted in terms of the unfolding of alpha-helices in the linker region. The change of the a-helices was confirmed by observing the recovery of the circular dichroism intensity. The TrL signal showed that the molecular volume decreases with two time constants; 300 mu s and 1.0 ms. The former time constant is close to the previously observed photo-dissociation reaction rate of the phot1-LOV2 (without the linker) dimer, and the latter one agrees well with the rate of the D-change. Considering a similar time constant of the dissociation reaction of the LOV2 dimer, we interpreted these kinetics in terms of the dissociation step of the linker region from the LOV2 domain (T-390(pre) state). After this step, the protein volume and D are decreased significantly with the lifetime of 1.0 ms. The D decrease indicates the increase of the intermolecular interaction between the protein and water molecules. On the basis of these observations, a two-step mechanism of the linker unfolding is proposed. (c) 2007 Elsevier Ltd. All rights reserved.