Crystal structure of Pseudomonas aeruginosa bacteriophytochrome:: Photoconversion and signal transduction
Crystal structure of Pseudomonas aeruginosa bacteriophytochrome:: Photoconversion and signal transduction
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DOI：
10.1073/pnas.0806718105
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发表时间：
2008-09-23
影响因子：
11.1
通讯作者：
Moffat, Keith
中科院分区：
文献类型：
--
作者：
Yang, Xiaojing;Kuk, Jane;Moffat, Keith
光敏色素是红光光感受器，其通过在红光（Pr）和远红光（Pfr）光吸收状态之间的可逆光转换来调节植物、真菌和细菌中的光响应。在这里，我们报告的晶体结构在2.9埃分辨率的细菌光敏色素从铜绿假单胞菌与完整的，完全光敏光敏核心域在其黑暗适应的PFR状态。这种结构揭示了如何不寻常的域间相互作用，包括结和"臂"结构附近的发色团网站，带来了PAS（每ARNT-Sim），GAF（cGMP磷酸二酯酶/腺苷酸环化酶/FhIA），和PHY（光敏色素）域，以实现Pr/Pfr光转换。PAS、GAF和PHY域具有共同的拓扑元素，并且可能具有单一的进化起源。我们确定了关键的相互作用，稳定在PFR状态的发色团，并提供结构和突变的证据，以支持有效的Pr/PFR光转换的PHY域的重要作用。我们还确定了一对保守的残基，可能会发生协调一致的构象变化，在光转换过程中。全长细菌光敏色素结构，包括其输出组氨酸激酶结构域的建模，表明如何在光敏域中起源的局部结构变化调节长，跨域信号螺旋之间的相互作用在二聚体界面和传输到空间上遥远的效应域，从而调节其组氨酸激酶活性。
Phytochromes are red-light photoreceptors that regulate light responses in plants, fungi, and bacteria via reversible photoconversion between red (Pr) and far-red (Pfr) light-absorbing states. Here we report the crystal structure at 2.9 angstrom resolution of a bacteriophytochrome from Pseudomonas aeruginosa with an intact, fully photoactive photosensory core domain in its dark-adapted Pfr state. This structure reveals how unusual interdomain interactions, including a knot and an "arm" structure near the chromophore site, bring together the PAS (Per-ARNT-Sim), GAF (cGMP phosphodiesterase/adenyl cyclase/FhIA), and PHY (phytochrome) domains to achieve Pr/Pfr photoconversion. The PAS, GAF, and PHY domains have topologic elements in common and may have a single evolutionary origin. We identify key interactions that stabilize the chromophore in the Pfr state and provide structural and mutational evidence to support the essential role of the PHY domain in efficient Pr/Pfr photoconversion. We also identify a pair of conserved residues that may undergo concerted conformational changes during photoconversion. Modeling of the full-length bacteriophytochrome structure, including its output histidine kinase domain, suggests how local structural changes originating in the photosensory domain modulate interactions between long, cross-domain signaling helices at the dimer interface and are transmitted to the spatially distant effector domain, thereby regulating its histidine kinase activity.