DATE2025.06.18 #Press Releases

Structure and Function of the Channelrhodopsin KnChR, Which Selectively Absorbs Indigo Light, Revealed

— Toward the Development of Multi-Wavelength Optogenetic Tools —

Summary

A research group led by Professor Osamu Nureki from the Graduate School of Science at the University of Tokyo and Distinguished Professor Hideki Kandori from the Department of Life and Materials Chemistry at Nagoya Institute of Technology has determined the three-dimensional structure of the dimeric channelrhodopsin (ChR) KnChR using single-particle analysis with cryo-electron microscopy (cryo-EM).

KnChR, a ChR derived from a zygnematophycean alga, was first reported in 2021 by Professor Kandori’s group. While most previously known ChRs function by absorbing blue-green (around 470 nm) or yellow-green light (around 540 nm), KnChR uniquely responds to shorter-wavelength indigo light at 450 nm. However, the mechanism behind this was previously unclear. In this study, the researchers revealed the mechanism by which KnChR senses indigo light by determining its structure with cryo-EM, and conducting electrophysiological and spectroscopic analyses.

Furthermore, based on its structural information, the team successfully engineered mutants of KnChR that respond to even shorter wavelengths, demonstrating its potential as a versatile tool for multi-wavelength optogenetics.

These findings pave the way for optogenetic studies of neural networks using indigo light. They also hold promise for advancing our understanding of mechanisms underlying psychiatric disorders such as depression, as well as heart diseases and muscular disorders such as muscular dystrophy, potentially leading to the development of new treatments.

Figure: The structure of the channelrhodopsin KnChR obtained by cryo-electron microscopy

Related Links

Nagoya Institute of Technology

Journals

Journal name	Nature Communications
Title of paper	Cryo-EM structure of a blue-shifted channelrhodopsin from Klebsormidium nitens.