Structural basis for ion selectivity in potassium-selective channelrhodopsins.

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 disti

SUBMITTER: Tajima S 

PROVIDER: S-EPMC7615185 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature