Berlin 2015 – scientific programme

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BP: Fachverband Biologische Physik

BP 52: Protein structure and dynamics II

BP 52.1: Invited Talk

Friday, March 20, 2015, 09:30–10:00, H 1028

Biophysics of light-activated ion transporters — Arend Vogt, Jonas Wietek, and •Peter Hegemann — Humboldt-Universität zu Berlin

The field of optogenetics utilizes light-activated ion transporters as channelrhodopsins (ChRs) and Arch3 for specific neuronal activation or inactivation. Recently we characterized a light-driven proton pump CsR of the arctic alga Coccomyxa subellipsoidea. Owing to the fact that the photocurrents are very large in Xenopus oocytes, we have taken this advantage to analyze the function of individual positions at the extracellular side of the retinal Schiff base chromophore respective relevance for proton transport. Modification of the highly conserved proton shuttling residue R83 or its interaction partner Y57 strongly reduced the power of the pumps and converted CsR at moderate electrochemical load into an operational proton channel with inward or outward rectification depending on the replacement. We compared these proton selective channels with various natural and artificial light-activated channels (channelrhodopsins) that are selective for protons, sodium and chloride and we derived principle for light-depending gating, ion conductance and selectivity of microbial rhodopsins.