Biophysical Society Thematic Meeting | Hamburg 2022

Biophysics at the Dawn of Exascale Computers

Poster Abstracts

34-POS Board 34 PROTEIN ENVIRONMENT GUIDES THE ENERGY TRANSFER IN THE LIGHT- HARVESTING COMPLEX OF DIATOMS Sayan Maity 1 ; Vangelis Daskalakis 2 ; Ulrich Kleinekathöfer 1 ; 1 Jacobs University Bremen, Department of Physics & Earth Sciences, Bremen, Germany 2 Cyprus University of Technology, Department of Chemical Engineering, Limassol, Cyprus The electrostatic protein environment of pigment molecules controls the excitation energy transfer (EET) process in the biological light-harvesting complexes. During the EET process, the excitation energies also known as site-energies of the pigment molecules are regulated by the fluctuating protein surroundings. In this work, we have performed a structure-based investigation of the fucoxanthin and chlorophyll-binding proteins (FCP) of diatoms [1, 2] to figure out the impact of the protein matrix on the site-energies of individual Chl-a and Chl-c1/c2 molecules in the complex. For this purpose, we have employed a multiscale analysis by combining molecular dynamics (MD) simulations and quantum chemistry (QC) calculations within quantum mechanics/molecular mechanics (QM/MM) framework [3]. We found that the QM/MM equilibrium geometry of Chl-c2 has the lowest site-energy within the protein environment for different QC methods. Moreover, the site-energy energies distributions of the FCP complex maintained the same trend for this pigment molecule along a QM/MM MD trajectory. These findings indicate that the energy transfer within the complex ends at this particular pigment. This finding is surprising since the lowest excitation energies of Chl-c molecules are known to be blue-shifted with respect to the Chl-a molecules in vacuum or in organic solvents. We conclude that the local protein solvation is responsible for creating a large electrostatic effect at the position of Chl-c2 leading to an unexpected energy shift.1. Wang et al. Science 2019, 363, eaav0365.2. Nagao et al. Nat. Plants 2019, 5, 890–901.3. Maity et al. J. Phys. Chem. Lett. 2020, 11, 20, 8660–8667.

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