The amino-terminal helix modulates light-activated conformational changes in AsLOV2

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• Light-oxygen-voltage (LOV) domains are crucial photoreceptors in optogenetics.
• Their light-triggered conformational changes and signaling mechanisms are not fully understood.
• The LOV2 domain of Avena sativa phototropin 1 (AsLOV2) is a key model system.

Purpose of the Study:

• To elucidate the mechanism of light-triggered signaling in AsLOV2.
• To identify novel regulatory elements controlling AsLOV2 conformational changes.
• To provide a framework for engineering improved LOV-based photoswitches.

Main Methods:

• Mutational analysis of AsLOV2.
• Circular dichroism spectroscopy.
• Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• The amino-terminal helix acts as a critical control element in AsLOV2 light activation.
• A direct amino-to-carboxy-terminal signaling pathway was identified.
• Illumination triggers a covalent bond formation and Jα helix release.

Conclusions:

• The study reveals a previously unrecognized role for the amino-terminal helix in LOV domain signaling.
• A comprehensive signaling pathway from light input to biological output is described.
• Findings offer new design strategies for advanced LOV-based photoswitchable proteins.