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Description
The previously characterized viral channelrhodopsin VirChR1 shows the necessary characteristics of an optogenetic tool. It also shows a unique impermeability for Ca$^{2+}$ ions, presumably helping avoid the impact of calcium influx, which is useful for the neuroscientific applications of optogenetics. VirChR1’s ability to drive neural firing is compromised by the low ion conductance. To fix this, it is necessary to improve the protein’s capacity to conduct photocurrents, while conserving its Ca$^{2+}$ sensitivity. Here, an approach called semi-rational mutagenesis is used in order to alter the rhodopsin’s characteristics in a desired fashion. Specifically, over 20 VirChR1’s mutants were electrophysiologically characterized to find the effects of the particular mutations on the function of VirChR1 and enhance its features through mutation combinations.
