Analog Retinal Redshifts Visible Absorption of QuasAr Transmembrane Voltage Sensors into Near-infrared
| Autor: | Kenneth J. Rothschild, Srividya Ganapathy, Natalia Mamaeva, Willem J. DeGrip, Peng Wang, Gaoxiang Mei |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
Materials science Photochemistry Biochemistry 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Amino Acid Sequence Physical and Theoretical Chemistry Absorption (electromagnetic radiation) Spectroscopy Research Articles Spectrum Analysis Near-infrared spectroscopy Membrane Proteins Retinal General Medicine Chromophore Polyene Fluorescence Optogenetics 030104 developmental biology chemistry Retinaldehyde Nanomedicine Radboud Institute for Molecular Life Sciences [Radboudumc 19] 030217 neurology & neurosurgery Visible spectrum Research Article |
| Zdroj: | Photochemistry and Photobiology, 96, 1, pp. 55-66 Photochemistry and Photobiology, 96(1), 55-66. WILEY Photochemistry and Photobiology Photochemistry and Photobiology, 96, 55-66 |
| ISSN: | 0031-8655 |
| Popis: | Opsin‐based transmembrane voltage sensors (OTVSs) are increasingly important tools for neuroscience enabling neural function in complex brain circuits to be explored in live, behaving animals. However, the visible wavelengths required for fluorescence excitation of the current generation of OTVSs limit optogenetic imaging in the brain to depths of only a few mm due to the strong absorption and scattering of visible light by biological tissues. We report that substitution of the native A1 retinal chromophore of the widely used QuasAr1/2 OTVSs with the retinal analog MMAR containing a methylamino‐modified dimethylphenyl ring results in over a 100‐nm redshift of the maxima of the absorption and fluorescence emission bands to near 700 and 840 nm, respectively. FT‐Raman spectroscopy reveals that at pH 7 QuasAr1 with both the A1 and MMAR chromophores possess predominantly an all‐trans protonated Schiff base configuration with the MMAR chromophore exhibiting increased torsion of the polyene single‐/double‐bond system similar to the O‐intermediate of the BR photocycle. In contrast, the A1 and the MMAR chromophores of QuasAr2 exist partially in a 13‐cis PSB configuration. These results demonstrate that QuasArs containing the MMAR chromophore are attractive candidates for use as NIR‐OTVSs, especially for applications such as deep brain imaging. QuasAr1 and QuasAr2, mutants of archaerhodopsin‐3, are used in optogenetic applications as fluorescent transmembrane voltage sensors. The native A1 retinal chromophore was substituted with a synthetic retinal analog MMAR containing a methylamino modified dimethylphenyl ring. The absorption, excitation and emission spectra were shifted from the visible to the near‐IR spectral region. FT‐Raman reveals information about the isomeric configuration of the MMAR chromophore in QuasArs. |
| Databáze: | OpenAIRE |
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