Molecular mechanism of calcium inhibition in viral channelrhodopsins.

Calcium inhibits viral channelrhodopsins by binding near the retinal cofactor, blocking essential conformational changes and preventing ion translocation.

• Why it matters: Understanding calcium's inhibitory mechanism is crucial for developing precise optogenetic tools and advancing knowledge of viral ion channel regulation.
• What they did: Using X-ray crystallography, UV-vis, and ATR-FTIR spectroscopy, the study identified a transient intracellular Ca 2+ binding site in OLPVR1 and examined its effects on ion conduction.
• The result: The findings clarify how calcium prevents channel opening by stabilizing the gate, enabling the design of improved calcium-sensitive optogenetic channels.