Light Signaling Mechanism of Two Tandem Bacteriophytochromes.
Light Signaling Mechanism of Two Tandem Bacteriophytochromes.
复制标题
两种串联细菌光敏色素的光信号机制。
DOI：
10.1016/j.str.2015.04.022
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Moffat,Keith
中科院分区：
文献类型：
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作者：
Yang,Xiaojing;Stojković,EminaA;Ozarowski,WesleyB;Kuk,Jane;Davydova,Erna;Moffat,Keith
RpBphP2和RpBphP3是来自palustris红假单胞菌（rhodopseudomonas palustris）的两个串联细菌色素，它们具有较高的序列同一性，但表现出不同的光转化行为。与标准的RpBphP2不同，RpBphP3光能转化为不寻常的近红吸收（Pnr）状态；两者都是在弱光条件下合成光收集配合物所必需的。本文报道了RpBphP2和RpBphP3光敏核心模块的晶体结构。虽然RpBphP2和RpBphP3的四级结构不同，但它们的三级结构几乎相同。RpBphP3结构揭示了GAF和PHY域之间界面的舌槽相互作用。GAF-PHY界面上PRxSF基序的单个突变可以消除RpBphP3中光诱导的Pnr状态的形成，这可能是由于发色团结合袋的结构刚性改变。结构比较表明，远程信号涉及二聚体界面螺旋棘的结构重排。这些结构与突变研究一起，为光敏色素的光转化和远程信号传导机制提供了见解。
RpBphP2 and RpBphP3, two tandem bacteriophytochromes from the photosynthetic bacteriumRhodopseudomonas palustris, share high sequence identity but exhibit distinct photoconversion behavior. Unlike the canonical RpBphP2, RpBphP3 photoconverts to an unusual near-red-absorbing (Pnr) state; both are required for synthesis of light-harvesting complexes under low-light conditions. Here we report the crystal structures of the photosensory core modules of RpBphP2 and RpBphP3. Despite different quaternary structures, RpBphP2 and RpBphP3 adopt nearly identical tertiary structures. The RpBphP3 structure reveals tongue-and-groove interactions at the interface between the GAF and PHY domains. A single mutation in the PRxSF motif at the GAF-PHY interface abolishes light-induced formation of the Pnr state in RpBphP3, possibly due to altered structural rigidity of the chromophore-binding pocket. Structural comparisons suggest that long-range signaling involves structural rearrangement of the helical spine at the dimer interface. These structures, together with mutational studies, provide insights into photoconversion and the long-range signaling mechanism in phytochromes.