Photocycle Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor QuasAr1

Abstract

The retinal photocycle dynamics of the fluorescent voltage sensor QuasAr1 (Archaerhodopsin 3 P60S-T80S-D95H-D106H-F161V mutant from Halorubrum sodomense) in pH 8 Tris buffer was studied. The samples were photoexcited to the first absorption band of the protonated retinal Schiff base (PRSB) Ret_580 (absorption maximum at λmax ≈ 580 nm), and the retinal Schiff base photoisomerization and protonation state changes were followed by absorption spectra recordings during light exposure and after light exposure. Ret_580 turned out to be composed of two protonated retinal Schiff base isomers, namely Ret_580I and Ret_580II. Photoexcitation of Ret_580I resulted in barrier-involved isomerization to Ret_540 (quantum yield ≈ 0.056) and subsequent retinal proton release leading to Ret_410 deprotonated retinal Schiff base (RSB). In the dark, Ret_410 partially recovered to Ret_580I and partially stabilized to irreversible Ret_400 due to apoprotein restructuring (Ret_410 lifetime ≈ 2 h). Photoexcitation of Ret_580II resulted in barrier-involved isomerization to Ret_640 (quantum yield ≈ 0.00135) and subsequent deprotonation to Ret_370 (RSB). In the dark, Ret_370 partially recovered to Ret_580II and partially stabilized to irreversible Ret_350 due to apoprotein restructuring (Ret_370 lifetime ≈ 10 h). Photocycle schemes and reaction coordinate diagrams for Ret_580I and Ret_580II were developed and photocyle parameters were determined.

All-optical electrophysiology with improved genetically encoded voltage indicators reveals interneuron network dynamics in vivo

“…As the starting template, we chose Archon1 (Piatkevich et al, 2018), which is an evolved version of Archaerhodopsin 3 that has been demonstrated for in vivo voltage imaging in mice (Fan et al, 2020;Piatkevich et al, 2019) and zebrafish larvae (Böhm et al, 2021). Since the voltage-sensing mechanism of rhodopsin-derived GEVIs is not fully understood (Maclaurin et al, 2013;Penzkofer et al, 2019Penzkofer et al, , 2021, it is difficult to adopt a structure-guided approach to design the mutant library.…”

The Physical Chemistry and Chemical Physics (PCCP) Section of the International Journal of Molecular Sciences in Its Publications: The First 300 Thematic Articles in the First 3 Years

“…This area is the largest in terms of the number of related publications and includes 91 articles, namely [ 1 , 2 , 3 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 , 151 , 152 , 153 ,…”

“…The last one seems to be the most detailed, and it is precisely this that we will try to implement in the course of our narrative. As it should be expected, a priori, most of the publications in this direction are devoted to organic compounds, and primarily organic molecules; these include, with varying degrees of correctness, publications [ 1 , 2 , 3 , 102 , 103 , 104 , 106 , 108 , 112 , 117 , 118 , 119 , 121 , 124 , 127 , 128 , 130 , 131 , 132 , 133 , 135 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 146 , 147 , 148 , 151 , 153 , 154 , 156 , 157 , 164 , 165 , 166 , 168 , 171 , 172 , 174 , 176 , 178 , 180 , 183 , 185 , 186 ]. Much less space is occupied by the works related to polymeric (in fact, to a high molecular weight) compounds [ 113 , …”

Absorption and Emission Spectroscopic Investigation of the Thermal Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor Archon2

“…Archaerhodopsin 3 (Arch) from Halorubrum sodomense exhibits measurable voltage dependence of fluorescence efficiency and was studied as voltage indicator [ 17 , 28 , 29 ]. For improvement of fluorescence efficiency and voltage sensitivity, variants of Arch have been synthesized by gene technical methods [ 28 , 29 , 30 , 31 , 32 , 35 , 37 , 43 , 44 , 45 , 46 ]. Arch and Arch D95N were used for optical recording of action potentials in cultured rat hippocampal neurons [ 28 ] and in HEK-293 cells [ 29 ].…”

“…The absorption and emission spectroscopic behavior and thermal stability of QuasAr1 was investigated in [ 44 ]. Its photocycle dynamics was studied in [ 45 ]. QuasAr3 (=QuasAr2 K171R) and paQuasAr3 (=QuasAr3 V59A) were applied to in vivo recording of supra- and subthreshold voltage dynamics from multiple neurons in mouse hippocampus [ 31 ].…”