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Publication Abstract from PubMed

The anion channelrhodopsin GtACR1 from the alga Guillardia theta is a potent neuron-inhibiting optogenetics tool. Presented here, its X-ray structure at 2.9 A reveals a tunnel traversing the protein from its extracellular surface to a large cytoplasmic cavity. The tunnel is lined primarily by small polar and aliphatic residues essential for anion conductance. A disulfide-immobilized extracellular cap facilitates channel closing and the ion path is blocked mid-membrane by its photoactive retinylidene chromophore and further by a cytoplasmic side constriction. The structure also reveals a novel photoactive site configuration that maintains the retinylidene Schiff base protonated when the channel is open. These findings suggest a new channelrhodopsin mechanism, in which the Schiff base not only controls gating, but also serves as a direct mediator for anion flux.

Crystal structure of a natural light-gated anion channelrhodopsin.,Li H, Huang CY, Govorunova EG, Schafer CT, Sineshchekov OA, Wang M, Zheng L, Spudich JL Elife. 2019 Jan 7;8. pii: 41741. doi: 10.7554/eLife.41741. PMID:30614787^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.