MerMAIDs: A novel family of metagenomically discovered, marine, anion-conducting and intensely desensitizing channelrhodopsins.

Johannes Oppermann, Paul Fischer, Arita Silapetere, Bernhard Liepe, Silvia RodriguezRozada, José Flores-Uribe, Enrico Peter, Anke Keidel, Johannes Vierock, Joel Kaufmann, Matthias Broser, Meike Luck, Franz Bartl, Peter Hildebrandt, J. Simon Wiegert, Oded Béjà, Peter Hegemann, & Jonas Wietek

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Apr 19, 2019
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Received Date: 11th April 19

Channelrhodopsins (ChRs) are algal light-gated ion channels widely used as optogenetic tools for manipulating neuronal activity. ChRs desensitize under continuous bright-light illumination, resulting in a significant decline of photocurrents. We describe a novel, metagenomically identified family of phylogenetically distinct anion-conducting ChRs (designated MerMAIDs). MerMAIDs almost completely desensitize during continuous illumination due to accumulation of a late non-conducting photointermediate that disrupts the ion permeation pathway. MerMAID desensitization can be fully explained by a single photocycle in which a long-lived desensitized state follows the short-lived conducting state. A conserved cysteine is the critical factor in desensitization, as its mutation results in recovery of large stationary photocurrents. The rapid desensitization of MerMAIDs enables their use as optogenetic silencers for transient suppression of individual action potentials without affecting subsequent spiking during continuous illumination. Our results could facilitate the development of further novel optogenetic tools from metagenomic databases and enhance general understanding of ChR function.

Read in full at bioRxiv.

This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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Nature Communications

Nature Research, Springer Nature