Scientists Uncover Molecular Recognition Mechanism of Infrared Optogenetic System to Enable Enhanced Deep Tissue Light Control

Chinese researchers uncover how Aff6 recognizes light states in the MagRed system, providing a blueprint for more precise deep tissue optogenetic tools.

By: AXL Media

Published: Apr 30, 2026, 8:11 AM EDT

Source: Information for this report was sourced from EurekAlert!

Decoding the Structural Language of Light Responsive Proteins

Optogenetics has emerged as a transformative field in biotechnology, allowing researchers to use light as a precise remote control for biological processes. However, for these systems to be effective in medical applications, they must be able to penetrate deep into human tissue without causing damage. Red and far-red light systems, such as the MagRed system, are ideal for this purpose due to their superior penetration and low phototoxicity. A research team led by Prof. Wang Junfeng and Associate Prof. Zhu Lei has now clarified the molecular mechanism behind this system, specifically how its components recognize and react to different states of light excitation.

Mapping the High Affinity Interactions of the MagRed System

The MagRed system relies on the interaction between a photosensitive protein called DrBphP and its binding partner, an affibody known as Aff6. Until now, the exact way Aff6 distinguished between the various light-induced states of the protein was a mystery that hindered efforts to optimize the technology. Using surface plasmon resonance, the researchers discovered that the monomeric photosensory core of DrBphP is the primary driver of this interaction. Most notably, they recorded a 23-fold difference in binding affinity between the Pfr and Pr states, proving that the system is highly sensitive to specific wavelengths of light.

Visualizing the Molecular Interface Through Nuclear Magnetic Resonance

To pinpoint exactly where these proteins touch, the team employed nuclear magnetic resonance titration and chemical shift perturbation analysis. This high-resolution mapping showed that Aff6 targets a specific phytochrome domain and the C-terminal region of the protein's helical spine. These findings were further supported by molecular docking and site-directed mutagenesis, which highlighted that aromatic interactions are the central force behind this state-specific recognition. By identifying these key contact points, the researchers have provided a physical blueprint of the system's internal machinery.