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Crystal structure of a natural light-gated anion channelrhodopsin.

ABSTRACT: 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 Å 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.

SUBMITTER: Li H

PROVIDER: S-EPMC6336409 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Crystal structure of a natural light-gated anion channelrhodopsin.

Li Hai H Huang Chia-Ying CY Govorunova Elena G EG Schafer Christopher T CT Sineshchekov Oleg A OA Wang Meitian M Zheng Lei L Spudich John L JL

eLife 20190107

The anion channelrhodopsin <i>Gt</i>ACR1 from the alga <i>Guillardia theta</i> is a potent neuron-inhibiting optogenetics tool. Presented here, its X-ray structure at 2.9 Å 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 photoa ...[more]

PMID: 30614787

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Crystal structure of the natural anion-conducting channelrhodopsin GtACR1.

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NEUROSCIENCE. Natural light-gated anion channels: A family of microbial rhodopsins for advanced optogenetics.

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