Photomodulation of reconstituted voltage-dependent K+ channels.

Abstract

The use of optogenetics for light-controlled ion flow has significantly impacted neuroscience, enabling isolated cell excitation or suppression within complex neural tissues. Achieving the same effect without the prior need to modify membrane channels genetically may represent a significant advantage for various applications. Here we tested whether photo-susceptible lipids may modulate the open probability of voltage-gated ion channels in their vicinity. The approach uses the observation that channel gating may be affected by membrane tension and depends on the material properties of the embedding lipid bilayer, such as spontaneous membrane curvature and membrane thickness [1]. We reconstituted KvAP, the voltage-gated potassium channel from Aeropyrum pernix, into photoswitchable horizontal solvent-depleted planar lipid bilayers. KvAP open probability suddenly increased when light exposure switched the photolipids from their conical to their cylindrical state. The effect was fully reversible as the photolipids could be switched back to their original state by exposure to light of a different wavelength. Single channel recordings and current recordings of channel ensembles confirmed the multiple repeatabilities of the photocycle. Our observation paves the way for the specific modulation of cells in vivo. This project was supported by a grant from the FWF (Austrian Science Fund): P34826. 1. Pfeffermann et al., Journal of Photochemistry and Photobiology B: Biology, 2021: p. 112320.