Ultrafast Dynamics of Heliorhodopsins
Ultrafast Dynamics of Heliorhodopsins
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日光视紫红质的超快动力学
DOI：
10.1021/acs.jpcb.9b00887
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Tahara Tahei
中科院分区：
文献类型：
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作者：
Tahara Shinya;Singh Manish;Kuramochi Hikaru;Shihoya Wataru;Inoue Keiichi;Nureki Osamu;B?j? Oded;Mizutani Yasuhisa;Kandori Hideki;Tahara Tahei
heliorhodopsin （HeR）是一个新的视紫红质家族，与1型和2型视紫红质序列同源性仅<15%。her与其他视紫红质之间氨基酸序列的巨大差异引发了一个问题，即它们的生物学功能是否像其他视紫红质一样，是由视网膜发色团的高效、快速光异构化引发的。我们对来自古热原体sg8 -52-1的两种HeR， HeR 48C12和HeR进行了飞秒时间分辨吸收测量。两者在480 nm附近表现出激发态吸收，在> ~ 650 nm区域表现出受激发射，这些瞬态信号在亚皮秒时间尺度上随光产物吸收的出现而衰减。观察到的光谱变化表明，超快视网膜光异构发生在飞秒时间区域。尽管在视网膜结合位点的疏水区域的氨基酸排列有显著差异，但HeRs的瞬态光谱和动力学与1型视紫红质惊人地相似。
Heliorhodopsins (HeR) constitute a new rhodopsin family and show only <15% sequence identities with type-1 and type-2 rhodopsins. The large difference in amino acid sequence between HeRs and other rhodopsins raises a question whether their biological function is triggered by efficient and rapid photoisomerization of the retinal chromophore as in the case of other rhodopsins. We performed femtosecond time-resolved absorption measurements of two HeRs, HeR 48C12 and HeR fromThermoplasmatales archaeonSG8-52-1. Both HeRs exhibit excited-state absorption around 480 nm and stimulated emission in the >650 nm region, and these transient signals decay concomitantly with appearance of photoproduct absorption on a subpicosecond time scale. The observed spectral change indicates that ultrafast retinal photoisomerization proceeds in the femtosecond time region. The transient spectra and dynamics of HeRs are surprisingly similar to those of type-1 rhodopsins, despite remarkable differences in amino acid arrangement in the hydrophobic region of the retinal binding site.