Identification of Cyanobacteriochromes Detecting Far-Red Light
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- 作者：Nathan C. Rockwell ; Shelley S. Martin ; J. Clark Lagarias
- 刊名：Biochemistry
- 出版年：2016
- 出版时间：July 19, 2016
- 年：2016
- 卷：55
- 期：28
- 页码：3907-3919
- 全文大小：750K
- 年卷期：0
- ISSN：1520-4995
文摘
The opacity of mammalian tissue to visible light and the strong attenuation of infrared light by water at ≥900 nm have contributed to growing interest in the development of far-red and near-infrared absorbing tools for visualizing and actuating responses within live cells. Here we report the discovery of cyanobacteriochromes (CBCRs) responsive to light in this far-red window. CBCRs are linear tetrapyrrole (bilin)-based light sensors distantly related to plant phytochrome sensors. Our studies reveal far-red (λb>max b> = 725–755 nm)/orange (λb>max b> = 590–600 nm) and far-red/red (λb>max b> = 615–685 nm) photoswitches that are small (<200 amino acids) and can be genetically reconstituted in living cells. Phylogenetic analysis and characterization of additional CBCRs demonstrated that far-red/orange CBCRs evolved after a complex transition from green/red CBCRs known for regulating complementary chromatic acclimation. Incorporation of different bilin chromophores demonstrated that tuning mechanisms responsible for red-shifted chromophore absorption act at the A-, B-, and/or C-rings, whereas photoisomerization occurs at the D-ring. Two such proteins exhibited detectable fluorescence extending well into the near-infrared region. This work extends the spectral window of CBCRs to the edge of the infrared, raising the possibility of using CBCRs in synthetic biology applications in the far-red region of the spectrum.