Dynamics of the Amino-Terminal and Carboxyl-Terminal Helices of Arabidopsis Phototropin 1 LOV2 Studied by the Transient Grating
Dynamics of the Amino-Terminal and Carboxyl-Terminal Helices of Arabidopsis Phototropin 1 LOV2 Studied by the Transient Grating
复制标题
瞬态光栅研究拟南芥向光素1 LOV2氨基端和羧基端螺旋的动力学
DOI：
10.1021/jp406109j
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
M. Terazima
中科院分区：
文献类型：
--
作者：
K.Takeda;Y.Nakasone;K.Zikihara;S.Tokutomi;M. Terazima
近年来，除了已报道的羧基端螺旋（Jα helix）的构象变化外，氨基端螺旋（A′α helix）的构象变化也被认为对拟南芥光致生长素1的光氧电压2结构域（LOV 2）的调节功能具有重要作用。然而，A′α螺旋的反应动力学尚未被研究。本文采用时间分辨瞬态光栅（TG）方法研究了拟南芥光诱素1（phototropin 1）LOV 2结构域A′α和Jα螺旋的去折叠反应。使A′α螺旋在黑暗状态下解折叠的突变体（T469 I突变体）显示Jα螺旋解折叠的时间常数为1 ms，这与野生型LOV 2-接头样品报告的时间常数非常相似。此外，一个突变体（I608 E突变体），使Jα螺旋展开在黑暗状态下表现出的A′α螺旋的解折叠过程的时间常数为12 ms的基础上，这些实验结果的基础上，这表明，这些螺旋的解折叠反应独立发生。
Recently, conformational changes of the amino-terminal helix (A′α helix), in addition to the reported conformational changes of the carboxyl-terminal helix (Jα helix), have been proposed to be important for the regulatory function of the light-oxygen-voltage 2 domain (LOV2) of phototropin 1 fromArabidopsis. However, the reaction dynamics of the A′α helix have not been examined. Here, the unfolding reactions of the A′α and Jα helices of the LOV2 domain of phototropin 1 fromArabidopsis thalianawere investigated by the time-resolved transient grating (TG) method. A mutant (T469I mutant) that renders the A′α helix unfolded in the dark state showed unfolding of the Jα helix with a time constant of 1 ms, which is very similar to the time constant reported for the wild-type LOV2-linker sample. Furthermore, a mutant (I608E mutant) that renders the Jα helix unfolded in the dark state exhibited an unfolding process of the A′α helix with a time constant of 12 ms. On the basis of these experimental results, it is suggested that the unfolding reactions of these helices occurs independently.