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

16 November 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

We report the results of a computational study of the mechanism of the light-induced chemical reaction of chromophore hydration in the fluorescent protein Dreiklang responsible for its switching from the fluorescent ON-state to the dark OFF-state. We explore the relief of the potential energy surface from the excited-state level of the charge-transfer character in the ON-state to locate conical intersection points with the ground state energy surface. Simulations of further evolution of model systems allow us to characterize the ground-state reaction intermediate tentatively suggested in the femtosecond studies of the light-induced dynamics in Dreiklang and finally to arrive to the reaction product. The obtained results clarify the details of the photoswitching mechanism in Dreiklang, which is due to the chemical modification of the fluorescent protein chromophore.

Keywords

fluorescent proteins 
photoswitching 
protein Dreiklang
chromophore hydration
molecular modeling
conical intersection points
QM/MM

Supplementary materials

Title
Description
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Title
Supporting materials for Modeling Light-Induced Chromophore Hydration in the Reversibly Photoswitchable Fluorescent Protein Dreiklang
Description
Supporting Materials contain illustration of the earlier proposed mechanisms (Sections S1, S2), details of the construction of the full-protein model (Section S3), and description of the files with atomic coordinates in the pdb-format (Section S4) deposited to the general-purpose open-access repository ZENODO, which can be accessed via https://doi.org/10.5281/zenodo.7323258.
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