Viral channelrhodopsins 1: Unique channels for novel optogenetics and disclosing molecular mechanisms of ion permeability

• Applicants: Taras Balandin, Ph.D.; Professor Dr. Josef Wachtveitl
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 568715301

The OPTOVCR project aims to disclose the molecular mechanism of ion permeability of viral channelrhodopsins (VCR1) with unprecedented detail and use this knowledge for the rational design of unique optogenetic tools based on VCR1. These light-dependent ion channels can trigger calcium signalling without altering the electrical properties of the plasma membrane. Recently, we showed that one of the VCR1s, OLPVR1 expressed in EPR, can trigger calcium signalling and control muscle contraction in tadpoles (Eria-Oliveira et al., 2024). We have also shown that OLPVR1 forms well-ordered crystals, allowing for the atomic resolution of 1.1 Å, making it a unique target for the project's aims. Complementary XFEL and synchrotron time-resolved X-ray crystallographic (TRX) accompanied by time-resolved (TR) spectroscopic (UV-Vis and FTIR) studies will be performed to disclose the mechanisms of ion permeability. Then, VCR1, enhanced variants with high light sensitivity, calcium permeability, and improved photokinetics, will be engineered. These VCR1s will be tested in cells and animal models to select the most perceptive tools for basic and medically relevant optogenetic research. V. Gordeliy's group will crystallize VCR1s and perform TRX studies on opening and closing VCR1s, while G. Sandoz’s group will conduct electrophysiological studies with selected enhanced VCR1s. The group of J. Wachtveitl will analyze the photokinetics of VCR1s, which is also necessary for planning TRX studies and interpretation of the structural data, and the group of T. Balandin will be responsible for genetic constructions and VCR1s production. The expected results will, for the first time, disclose molecular mechanisms of channelrhodopsins ion permeability in great detail and may significantly impact the studies of calcium signalling, a key process in biology.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partners: Professor Dr. Valentin Gordeliy; Privatdozent Dr. Guillaume Sandoz