Impact of the Protein Environment on Two-Photon Absorption Cross-Sections of the GFP Chromophore Anion Resolved at the XMCQDPT2 Level of Theory

The search for fluorescent proteins with large two-photon absorption (TPA) cross-sections and improved brightness is required for their efficient use in bioimaging. Here, we explored the impact of a single-point mutation close to the anionic form of the GFP chromophore on its TPA activity. We consid...

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Bibliographic Details
Published in:International journal of molecular sciences 2023-07, Vol.24 (14), p.11266
Main Authors: Aslopovsky, Vladislav R, Scherbinin, Andrei V, Kleshchina, Nadezhda N, Bochenkova, Anastasia V
Format: Article
Language:English
Subjects:
Anions
Chromophores
Coloring Agents
Electric fields
Fluorescence
Gene mutations
Green Fluorescent Proteins - metabolism
Hydrogen
Hydrogen bonds
Lasers
Luminescent Proteins - chemistry
Microscopy
Molecular Conformation
Molecular dynamics
Molecular Dynamics Simulation
Mutation
Proteins
Surface active agents
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Summary:The search for fluorescent proteins with large two-photon absorption (TPA) cross-sections and improved brightness is required for their efficient use in bioimaging. Here, we explored the impact of a single-point mutation close to the anionic form of the GFP chromophore on its TPA activity. We considered the lowest-energy transition of EGFP and its modification EGFP T203I. We focused on a methodology for obtaining reliable TPA cross-sections for mutated proteins, based on conformational sampling using molecular dynamics simulations and a high-level XMCQDPT2-based QM/MM approach. We also studied the numerical convergence of the sum-over-states formalism and provide direct evidence for the applicability of the two-level model for calculating TPA cross-sections in EGFP. The calculated values were found to be very sensitive to changes in the permanent dipole moments between the ground and excited states and highly tunable by internal electric field of the protein environment. In the case of the GFP chromophore anion, even a single hydrogen bond was shown to be capable of drastically increasing the TPA cross-section. Such high tunability of the nonlinear photophysical properties of the chromophore anions can be used for the rational design of brighter fluorescent proteins for bioimaging using two-photon laser scanning microscopy.
ISSN:1422-0067
1661-6596
1422-0067
DOI:10.3390/ijms241411266