From primary photochemistry to biological function in the blue-light photoreceptors PYP and AppA
From primary photochemistry to biological function in the blue-light photoreceptors PYP and AppA
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蓝光光感受器 PYP 和 AppA 从初级光化学到生物功能
DOI：
10.1039/b418442b
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发表时间：
2005
影响因子：
3.1
通讯作者：
K. Hellingwerf
中科院分区：
文献类型：
--
作者：
M. Horst;W. Laan;S. Yeremenko;A. Wende;P. Palm;D. Oesterhelt;K. Hellingwerf
为了适当地应对流畅性条件的变化，Nature开发了各种光传感器来调节基因表达、酶活性和/或运动。专门的类型已经进化，可分为六个家族：视紫红质、光敏色素、黄嘌呤、隐色素、嗜光蛋白和bluf蛋白。前三个家族的光化学反应是基于乙烯键的顺/反异构化。令人惊讶的是，后三种都使用黄素作为它们的发色团，但每种都有非常不同的光化学。在这篇文章中，我们将讨论黄素（来自嗜盐盐螺旋藻的光活性黄蛋白（PYP））的信号产生的分子基础，黄素是一种负趋光性的光感受器，而BLUF蛋白（来自球形红杆菌的AppA）是一种转录抗抑制因子。PYP通过其4-羟基肉桂酸发色团的7,8-乙烯基键的反式/顺式异构化被激活。这启动了一个具有多种中间体的光循环，如pB，这是在分子内质子转移后形成的。在蛋白质内部形成的负电荷触发了部分展开的信号状态的形成。对于AppA，人们对其潜在的光化学知之甚少。现有证据表明，这是基于光诱导的黄素发色团氢键的变化和/或黄素和/或附近芳香氨基酸（如Y21）之间疏水堆叠的变化。信号状态在微秒内形成，恢复速率为~10^-3 s^-1。然而，与PYP相比，AppA中受体和信号状态之间的构象变化似乎很小。本文综述了这两种光感受器蛋白在光循环的各个步骤中的潜在化学作用，并提供了它们的机制和功能的新数据。
To properly respond to changes in fluency conditions, Nature has developed a variety of photosensors that modulate gene expression, enzyme activity and/or motility. Dedicated types have evolved, which can be classified in six families: rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins and BLUF-proteins. The photochemistry of the first three families is based on cis / trans isomerization of an ethylene bond. Surprisingly, the latter three all use flavin as their chromophore, but each with very different photochemistry. In this contribution we will discuss the molecular basis of signal generation in a xanthopsin (Photoactive Yellow Protein (PYP) from Halorhodospira halophila ), a photoreceptor for negative phototaxis, and in a BLUF protein (AppA from Rhodobacter sphaeroides ), a transcriptional anti-repressor. PYP is activated through trans / cis isomerization of the 7,8-vinyl bond of its 4-hydroxycinnamic acid chromophore. This initiates a photocycle with multiple intermediates, like pB, which is formed after intramolecular proton transfer. The negative charge thus formed in the interior of the protein triggers formation of a partially unfolded signaling state. For AppA much less is known about the underlying photochemistry. Available evidence suggests that it is based on a light-induced change in the hydrogen-bonding of its flavin chromophore and/or a change in hydrophobic stacking between the flavin and/or nearby aromatic amino acids like Y21. A signaling state is formed within microseconds, which recovers with a rate of ~10^-3 s^-1. The change in conformation between receptor- and signaling-state in AppA, however, appear to be minute as compared to those in PYP. Here we review the underlying chemistry in the various steps of the photocycle of these two photoreceptor proteins and provide new data on their mechanism and function.
异源表达的 BLUF 结构域的发色团组成
影响因子：
3.1
作者：
W. Laan;T. Bednarz;J. Heberle;K. J. Hellingwerf
通讯作者：
K. J. Hellingwerf
影响因子：
5.7
作者：
Anderson, S;Srajer, V;Moffat, K
通讯作者：
Moffat, K