TP 08: The photochromism of Channelrhodopsin-1 of Volvox carteri (VCHR)

Channelrhodopsins (ChRs) are directly light-gated ion channels of green algae used for orientation in the light. In the neurosciences ChRs are used for excitation of selected cells in neuronal tissues or living animals simply by light (Optogenetics). Such method opens wide perspectives for specific activation of defined cells in the brain and to study neuronal disorders. Recently we achieved to functionally express ChR in COS-cells and to analyse the photocycle in detail. ChR1 of the colonial alga Volvox carteri showed an sbsorption 70 nm red shifted (535 nm) compared to that of Chlamydomonas ChR2 (lmax: 465 nm). In the project we are applying for we aim to design new ChR2 with absorption maxima covering the whole visible range from 400 to 600 nm. The design will be based on theoretical calculations and spectroscopic studies on Volvox-ChR1 and Chlamdomonas ChR2. Functionality of the new proteins will be studied using electrophysiology and spectroscopy. Finally, we will test the new proteins in hippocampal cells and animal model systems.