Slow Conformational Changes of Blue Light Sensor BLUF Proteins in Milliseconds
Slow Conformational Changes of Blue Light Sensor BLUF Proteins in Milliseconds
复制标题
蓝光传感器 BLUF 蛋白质在几毫秒内缓慢构象变化
DOI：
10.1021/jacs.1c13121
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发表时间：
2022
影响因子：
15
通讯作者：
Terazima Masahide
中科院分区：
文献类型：
--
作者：
Tokonami Shunrou;Onose Morihiko;Nakasone Yusuke;Terazima Masahide
使用黄素 (BLUF) 蛋白的蓝光传感器由黄素结合 BLUF 结构域和功能结构域组成。在蓝光激发下，黄素发色团周围的氢键网络发生变化，可见光区域的吸收光谱呈现红移。最终，BLUF域接收到的光信息被传输到功能区。人们相信这种红移在纳秒内完成。在这项研究中，所有检查的 BLUF 蛋白（AppA、OaPAC、BlrP1、YcgF、PapB、SyPixD 和 TePixD）都发现了毫秒级的慢反应动力学（τ1 和 τ2 相）。尽管关于 BLUF 的报道很多，但这是首次清楚地观察到 BLUF 蛋白质吸收随毫秒时间区域持续时间的变化。通过对 OaPAC 的一些结构域缺失突变体和 PixD 蛋白的两个嵌合突变体的测量，发现较慢的动力学（τ2 相）受到与 BLUF 结构域相邻的 C 端区域的大小和性质的强烈影响。因此，这种毫秒反应是 C 端区域构象变化的重要指标，这对于生物功能至关重要。另一方面，τ1 相普遍存在于所有 BLUF 蛋白中，包括任何突变体。使用位点特异性突变体研究了缓慢动力学的起源。这些结果清楚地表明了色氨酸在 BLUF 结构域中的重要性。在此基础上，提出了BLUF反应的反应方案。
Blue light sensor using flavin (BLUF) proteins consist of flavin-binding BLUF domains and functional domains. Upon blue light excitation, the hydrogen bond network around the flavin chromophore changes, and the absorption spectrum in the visible region exhibits a red shift. Ultimately, the light information received in the BLUF domain is transmitted to the functional region. It has been believed that this red shift is complete within nanoseconds. In this study, slow reaction kinetics were discovered in milliseconds (τ1- and τ2-phase) for all the BLUF proteins examined (AppA, OaPAC, BlrP1, YcgF, PapB, SyPixD, and TePixD). Despite extensive reports on BLUF, this is the first clear observation of the BLUF protein absorption change with the duration in the millisecond time region. From the measurements of some domain-deleted mutants of OaPAC and two chimeric mutants of PixD proteins, it was found that the slower dynamics (τ2-phase) are strongly affected by the size and nature of the C-terminal region adjacent to the BLUF domain. Hence, this millisecond reaction is a significant indicator of conformational changes in the C-terminal region, which is essential for the biological functions. On the other hand, the τ1-phase commonly exists in all BLUF proteins, including any mutants. The origin of the slow dynamics was studied using site-specific mutants. These results clearly show the importance of Trp in the BLUF domain. Based on this, a reaction scheme for the BLUF reaction is proposed.