Expanding the Optogenetics Toolkit by Topological Inversion of Rhodopsins

• Published in: Cell Vol. 175; no. 4; pp. 1131 - 1140.e11
• Main Authors: Brown, Jennifer, Behnam, Reza, Coddington, Luke, Tervo, D.G.R., Martin, Kathleen, Proskurin, Mikhail, Kuleshova, Elena, Park, Junchol, Phillips, James, Bergs, Amelie C.F., Gottschalk, Alexander, Dudman, Joshua T., Karpova, Alla Y.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-11-2018
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/j.cell.2018.09.026

Targeted manipulation of activity in specific populations of neurons is important for investigating the neural circuit basis of behavior. Optogenetic approaches using light-sensitive microbial rhodopsins have permitted manipulations to reach a level of temporal precision that is enabling functional circuit dissection. As demand for more precise perturbations to serve specific experimental goals increases, a palette of opsins with diverse selectivity, kinetics, and spectral properties will be needed. Here, we introduce a novel approach of “topological engineering”—inversion of opsins in the plasma membrane—and demonstrate that it can produce variants with unique functional properties of interest for circuit neuroscience. In one striking example, inversion of a Channelrhodopsin variant converted it from a potent activator into a fast-acting inhibitor that operates as a cation pump. Our findings argue that membrane topology provides a useful orthogonal dimension of protein engineering that immediately permits as much as a doubling of the available toolkit.
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•Transmembrane proteins can be inverted via recombination with N-terminal domains•Topological inversion of rhodopsins yields new variants with unique properties•Inversion of ChRET/TC reverses cationic flux creating a potent inhibitor: FLInChR
By topologically inverting opsin proteins within the membrane, it may be possible to double the existing toolkit available for optogenetics