Photoreaction Dynamics of Full-Length Phototropin from Chlamydomonas reinhardtii
Photoreaction Dynamics of Full-Length Phototropin from Chlamydomonas reinhardtii
复制标题
莱茵衣藻全长向光素的光反应动力学
DOI：
10.1021/acs.jpcb.9b09685
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Terazima Masahide
中科院分区：
文献类型：
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作者：
Nakasone Yusuke;Ohshima Masumi;Okajima Koji;Tokutomi Satoru;Terazima Masahide
趋光蛋白（Phototropin，phot）是一种蓝光感受器，参与了从绿色藻类到高等植物的多种光反应。Phot由两个光感受结构域（LOV 1和LOV 2）和一个Ser/Thr激酶结构域组成。这些结构域通过铰链和接头结构域连接。迄今为止，光化学反应动力学的研究仅限于短片段，完整的光化学反应还没有得到很好的阐明。本文用瞬态光栅和圆二色性（CD）方法研究了莱茵衣藻（Chlamyderplaeinhardtii，Cr）的全长光敏剂和几种突变体的光反应。全长Crphot是在黑暗和光明状态下的单体形式，并显示光激发后的构象变化。当LOV 1被激发时，铰链螺旋展开的时间常数为77毫秒。LOV 2激发后，接头螺旋展开最初其次是三级结构的激酶结构域的变化，时间常数为91毫秒。LOV 2的加合物形成后的构象变化的量子产率远小于LOV 1，表明反应性和非反应性形式存在。与LOV 1和LOV 2的激发相关的构象变化独立地和相加地发生，即使当它们同时被激发时。因此，LOV 1的作用不是增强激酶活性，除了LOV 2的功能，我们建议LOV 1有不同的功能，如调节分子间的相互作用。
Phototropin (phot) is a blue light sensor involved in the light responses of several species from green algae to higher plants. Phot consists of two photoreceptive domains (LOV1 and LOV2) and a Ser/Thr kinase domain. These domains are connected by a hinge and a linker domain. So far, studies on the photochemical reaction dynamics of phot have been limited to short fragments, and the reactions of intact phot have not been well elucidated. Here, the photoreactions of full-length phot and of several mutants fromChlamydomonas reinhardtii(Cr) were investigated by the transient grating and circular dichroism (CD) methods. Full-lengthCrphot is in monomeric form in both dark and light states and shows conformational changes upon photoexcitation. When LOV1 is excited, the hinge helix unfolds with a time constant of 77 ms. Upon excitation of LOV2, the linker helix unfolds initially followed by a tertiary structural change of the kinase domain with a time constant of 91 ms. The quantum yield of conformational change after adduct formation of LOV2 is much smaller than that of LOV1, indicating that reactive and nonreactive forms exist. The conformational changes associated with the excitations of LOV1 and LOV2 occur independently and additively, even when they are excited simultaneously. Hence, the role of LOV1 is not to enhance the kinase activity in addition to LOV2 function; we suggest LOV1 has different functions such as regulation of intermolecular interactions.