Fernandez Lahore, R.G., Pampaloni, N.P., Peter, E., Heim, M.M., Tillert, L., Vierock, J., Oppermann, J., Walther, J., Schmitz, D., Owald, D., Plested, A.J.R., Rost, B.R., Hegemann, P. (2022). Calcium-permeable channelrhodopsins for the photocontrol of calcium signalling.  Nat. Commun. 13(1): 7844.

FBrf0255368

Research paper

Channelrhodopsins are light-gated ion channels used to control excitability of designated cells in large networks with high spatiotemporal resolution. While ChRs selective for H+, Na+, K+ and anions have been discovered or engineered, Ca2+-selective ChRs have not been reported to date. Here, we analyse ChRs and mutant derivatives with regard to their Ca2+ permeability and improve their Ca2+ affinity by targeted mutagenesis at the central selectivity filter. The engineered channels, termed CapChR1 and CapChR2 for calcium-permeable channelrhodopsins, exhibit reduced sodium and proton conductance in connection with strongly improved Ca2+ permeation at negative voltage and low extracellular Ca2+ concentrations. In cultured cells and neurons, CapChR2 reliably increases intracellular Ca2+ concentrations. Moreover, CapChR2 can robustly trigger Ca2+ signalling in hippocampal neurons. When expressed together with genetically encoded Ca2+ indicators in Drosophila melanogaster mushroom body output neurons, CapChRs mediate light-evoked Ca2+ entry in brain explants.

PMC9772239 (PMC) (EuropePMC)