An evolutionarily conserved iron-sulfur cluster underlies redox sensory function of the Chloroplast Sensor Kinase
An evolutionarily conserved iron-sulfur cluster underlies redox sensory function of the Chloroplast Sensor Kinase
复制标题
DOI：
10.1038/s42003-019-0728-4
复制
发表时间：
2020-01-08
影响因子：
5.9
通讯作者：
Puthiyaveetil, Sujith
中科院分区：
文献类型：
--
作者：
Ibrahim, Iskander M.;Wu, Huan;Puthiyaveetil, Sujith
光合效率取决于两个光谱不同的串联光合系统的相等光能转换。位于两个光系统之间的质体醌池的氧化还原状态是启动光系统相对丰度的适应性变化的关键调节信号。叶绿体传感激酶（CSK）将质体醌氧化还原信号与光系统基因表达联系起来，但其监测质体醌氧化还原状态的机制尚不清楚。在这里，我们表明，纯化的拟南芥和褐指藻CSK和蓝藻CSK同系物，组氨酸激酶2（HIK 2），是铁硫蛋白。CSK的Fe-S簇是一个高电位的氧化还原响应[3Fe-4S]中心。CSK响应于氧化还原剂，还原质体醌抑制其自身激酶活性。CSK铁硫簇内的氧化还原变化转化为蛋白质折叠中的构象变化。Ibrahim等人的研究表明，拟南芥和褐指藻的叶绿体传感器激酶（CSK）以及蓝藻的CSK同源物组氨酸激酶2都是铁硫蛋白。这项研究提供了深入了解如何CSK为基础的叶绿体双组分系统感知和传播质体醌氧化还原信号。
Photosynthetic efficiency depends on equal light energy conversion by two spectrally distinct, serially-connected photosystems. The redox state of the plastoquinone pool, located between the two photosystems, is a key regulatory signal that initiates acclimatory changes in the relative abundance of photosystems. The Chloroplast Sensor Kinase (CSK) links the plastoquinone redox signal with photosystem gene expression but the mechanism by which it monitors the plastoquinone redox state is unclear. Here we show that the purified Arabidopsis and Phaeodactylum CSK and the cyanobacterial CSK homologue, Histidine kinase 2 (Hik2), are iron-sulfur proteins. The Fe-S cluster of CSK is further revealed to be a high potential redox-responsive [3Fe-4S] center. CSK responds to redox agents with reduced plastoquinone suppressing its autokinase activity. Redox changes within the CSK iron-sulfur cluster translate into conformational changes in the protein fold. These results provide key insights into redox signal perception and propagation by the CSK-based chloroplast two-component system.Ibrahim et al. show that the Arabidopsis and Phaeodactylum Chloroplast Sensor Kinase (CSK) and the cyanobacterial CSK homologue, Histidine kinase 2, are iron sulfur proteins. This study provides insights into how the CSK-based chloroplast two-component system perceives and propagates the plastoquinone redox signals.