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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >The Structure Of A Complete Phytochrome Sensory Module In The Pr Ground State
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The Structure Of A Complete Phytochrome Sensory Module In The Pr Ground State

机译：Pr基态的完整植物色素感官模块的结构

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Phytochromes are red/far-red photochromic biliprotein photore-ceptors, which in plants regulate seed germination, stem extension, flowering time, and many other light effects. However, the structure/functional basis of the phytochrome photoswitch is still unclear. Here, we report the ground state structure of the complete sensory module of Cph1 phytochrome from the cyanobacterium Synechocystis 6803. Although the phycocyanobilin (PCB) chro-mophore is attached to Cys-259 as expected, paralleling the situation in plant phytochromes but contrasting to that in bacterio-phytochromes, the ZZZssa conformation does not correspond to that expected from Raman spectroscopy. We show that the PHY domain, previously considered unique to phytochromes, is structurally a member of the GAF (cGMP phosphodiesterase/adenylyl cyclase/FhIA) family. Indeed, the tandem-GAF dumbbell revealed for phytochrome sensory modules is remarkably similar to the regulatory domains of cyclic nucleotide (cNMP) phosphodiester-ases and adenylyl cyclases. A unique feature of the phytochrome structure is a long, tongue-like protrusion from the PHY domain that seals the chromophore pocket and stabilizes the photoacti-vated far-red-absorbing state (Pfr). The tongue carries a conserved PRxSF motif, from which an arginine finger points into the chromophore pocket close to ring D forming a salt bridge with a conserved aspartate residue. The structure that we present provides a framework for light-driven signal transmission in phytochromes.
机译：植物色素是红色/远红色的光致变色胆蛋白光受体，在植物中调节种子发芽，茎伸长，开花时间和许多其他光效应。然而，植物色素光电开关的结构/功能基础仍不清楚。在这里，我们报道了来自蓝藻细菌Synechocystis 6803的Cph1植物色素的完整感觉模块的基态结构。尽管藻蓝素（PCB）色团如预期般附着在Cys-259上，与植物光色素的情况平行，但与之相反在细菌性植物色素中，ZZZssa构象与拉曼光谱法预期的构象不符。我们显示，以前认为是植物色素唯一的PHY域在结构上是GAF（cGMP磷酸二酯酶/腺苷酸环化酶/ FhIA）家族的成员。实际上，揭示用于植物色素感觉模块的串联GAF哑铃与环状核苷酸（cNMP）磷酸二酯酶和腺苷酸环化酶的调节域非常相似。植物色素结构的独特特征是从PHY域发出的长舌状突起，可密封发色团并稳定光活化的远红外吸收状态（Pfr）。舌头带有保守的PRxSF基序，精氨酸手指从该基团指向靠近D环的生色团口袋，形成带有保守的天冬氨酸残基的盐桥。我们目前的结构为光致色素中光驱动信号的传输提供了框架。

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