Predicting Mutation-Induced Changes in the Electronic Properties of Photosynthetic Proteins from First Principles:...

Area of Science:

• Biophysics
• Computational Biology
• Photosynthesis Research

Background:

• The Fenna-Matthews-Olson (FMO) complex is crucial for light harvesting in photosynthetic bacteria.
• Understanding how mutations affect pigment-protein interactions is key to deciphering energy transfer mechanisms.

Purpose of the Study:

• To predict optical absorption and circular dichroism spectra of FMO complex mutants using multiscale molecular modeling.
• To investigate the impact of single-point mutations (Y16F and Q198V) on pigment electronic properties and protein structure.

Main Methods:

• Multiscale molecular modeling combining classical molecular dynamics simulations.
• Structural refinement of photosynthetic pigments within a polarizable protein environment.
• Excited-state calculations using first-principles methods, with X-ray structure of wild-type protein as input.

Main Results:

• The modeling successfully reproduced experimental spectral changes for Y16F and Q198V mutants.
• The Q198V mutation showed minimal impact on the primary bacteriochlorophyll *a* pigment's electronic properties.
• Significant electronic property changes were observed in other pigments, indicating long-range effects of the mutation.

Conclusions:

• Single-point mutations can induce long-range structural alterations in the FMO complex.
• Local structural changes near a pigment do not always correlate with significant alterations in its electronic properties.
• Multiscale modeling is a powerful tool for predicting spectral properties and understanding mutation effects in pigment-protein complexes.