Faculty, Staff and Student Publications
Publication Date
2-3-2025
Journal
Nature Communications
Abstract
Structural information on channelrhodopsins' mechanism of light-gated ion conductance is scarce, limiting its engineering as optogenetic tools. Here, we use single-particle cryo-electron microscopy of peptidisc-incorporated protein samples to determine the structures of the slow-cycling mutant C110A of kalium channelrhodopsin 1 from Hyphochytrium catenoides (HcKCR1) in the dark and upon laser flash excitation. Upon photoisomerization of the retinal chromophore, the retinylidene Schiff base NH-bond reorients from the extracellular to the cytoplasmic side. This switch triggers a series of side chain reorientations and merges intramolecular cavities into a transmembrane K+ conduction pathway. Molecular dynamics simulations confirm K+ flux through the illuminated state but not through the resting state. The overall displacement between the closed and the open structure is small, involving mainly side chain rearrangements. Asp105 and Asp116 play a key role in K+ conductance. Structure-guided mutagenesis and patch-clamp analysis reveal the roles of the pathway-forming residues in channel gating and selectivity.
Keywords
Channelrhodopsins, Potassium, Molecular Dynamics Simulation, Cryoelectron Microscopy, Ion Channel Gating, Light, Protein Conformation
DOI
10.1038/s41467-025-56491-9
PMID
39900567
PMCID
PMC11790859
PubMedCentral® Posted Date
2-3-2025
PubMedCentral® Full Text Version
Post-print
Published Open-Access
yes