Modeling Light-Induced Chromophore Hydration in the Reversibly Photoswitchable Fluorescent Protein Dreiklang

Area of Science:

• Photochemistry
• Biophysics
• Computational Chemistry

Background:

• Fluorescent proteins like Dreiklang are crucial for biological imaging and manipulation.
• Understanding the photoswitching mechanism of fluorescent proteins is key to their application.
• Dreiklang exhibits light-induced switching between fluorescent ON and non-fluorescent OFF states.

Purpose of the Study:

• To computationally elucidate the mechanism of light-induced chromophore hydration in Dreiklang.
• To investigate the transition from the ON-state to the OFF-state.
• To characterize the reaction intermediate and product of the photoswitching process.

Main Methods:

• Computational study employing potential energy surface calculations.
• Exploration of charge-transfer excited-state and ground-state energy surfaces.
• Simulations of system evolution to identify reaction pathways and intermediates.

Main Results:

• Located minimum energy conical intersection points between excited and ground states.
• Characterized the ground-state reaction intermediate.
• Identified the final reaction product, clarifying the photoswitching pathway.
• Confirmed that chromophore chemical modification governs the photoswitching mechanism.

Conclusions:

• The study clarifies the detailed photoswitching mechanism of the fluorescent protein Dreiklang.
• Light-induced chromophore hydration is the key process driving the ON-to-OFF state transition.
• Computational methods provide valuable insights into the dynamics of fluorescent proteins.