EMD-35713

Single-particle
2.66 Å
EMD-35713 Deposition: 23/03/2023
Map released: 06/09/2023
Last modified: 06/11/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-35713

Cryo-EM structure of the potassium-selective channelrhodopsin HcKCR1 H225F mutant in lipid nanodisc

EMD-35713

Single-particle
2.66 Å
EMD-35713 Deposition: 23/03/2023
Map released: 06/09/2023
Last modified: 06/11/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Hyphochytrium catenoides
Sample: HcKCR1
Fitted models: 8iu0 (Avg. Q-score: 0.636)
Raw data: EMPIAR-11558

Deposition Authors: Tajima S , Kim Y, Nakamura S, Yamashita K , Fukuda M, Deisseroth K, Kato HE
Structural basis for ion selectivity in potassium-selective channelrhodopsins.
PUBMED: 37652010
DOI: doi:10.1016/j.cell.2023.08.009
ISSN: 1097-4172
Abstract:
KCR channelrhodopsins (K+-selective light-gated ion channels) have received attention as potential inhibitory optogenetic tools but more broadly pose a fundamental mystery regarding how their K+ selectivity is achieved. Here, we present 2.5-2.7 Å cryo-electron microscopy structures of HcKCR1 and HcKCR2 and of a structure-guided mutant with enhanced K+ selectivity. Structural, electrophysiological, computational, spectroscopic, and biochemical analyses reveal a distinctive mechanism for K+ selectivity; rather than forming the symmetrical filter of canonical K+ channels achieving both selectivity and dehydration, instead, three extracellular-vestibule residues within each monomer form a flexible asymmetric selectivity gate, while a distinct dehydration pathway extends intracellularly. Structural comparisons reveal a retinal-binding pocket that induces retinal rotation (accounting for HcKCR1/HcKCR2 spectral differences), and design of corresponding KCR variants with increased K+ selectivity (KALI-1/KALI-2) provides key advantages for optogenetic inhibition in vitro and in vivo. Thus, discovery of a mechanism for ion-channel K+ selectivity also provides a framework for next-generation optogenetics.