Work

Origin of the red-shifted absorption maximum in channelrhodopsin Chrimson

Year: 2025

Type: article

Abstract: = 590 nm). This unique absorption makes it an ideal candidate for noninvasive optogenetic applications. The origin of the absorption maximum is thought to stem from a single deprotonated counterion near the Schiff base. However, it remains unclear which of the two potential counterions, E165 and D295, is protonated. In addition, a third titratable residue (E132) near the chromophore may also play a role in the spectral tuning mechanism. A single mutation from serine to alanine (S169A) further red-shifts the absorption maximum to 608 nm. Here we elucidate the mechanism behind the red-shifted absorption maximum using classical molecular dynamics simulations in tandem with hybrid QM/MM simulations. We found that protonation of both E165 and E132 leads to the correct experimental absorption trend for the wild type. This was further validated for the S169A mutant. The derived understanding of the spectral shift will guide the experimental design of red-shifted microbial rhodopsins.

Source: Chemical Communications

DOI: 10.1039/d5cc02654g

Authors: Jonathan R. Church, Probal Nag, Tal Dogon, Igor Schapiro

Institutions: Hebrew University of Jerusalem, TU Dortmund University, Ruhr University Bochum

Language: English

Topic: Photoreceptor and optogenetics research

Subfield: Cellular and Molecular Neuroscience

Field: Neuroscience

Domain: Life Sciences

Open Access status: hybrid

Funders: Deutsche Forschungsgemeinschaft, Israel Science Foundation

Awards: G3390287098, G673330677