Predicting Mutation-Induced Changes in the Electronic Properties of Photosynthetic Proteins from First Principles: The Fenna-Matthews-Olson Complex Example

Multiscale molecular modeling is utilized to predictoptical absorptionand circular dichroism spectra of two single-point mutants of theFenna-Matthews-Olson photosynthetic pigment-proteincomplex. The modeling approach combines classical molecular dynamicssimulations with structural refinement of photosynthetic pigmentsand calculations of their excited states in a polarizable proteinenvironment. The only experimental input to the modeling protocolis the X-ray structure of the wild-type protein. The first-principlesmodeling reproduces changes in the experimental optical spectra ofthe considered mutants, Y16F and Q198V. Interestingly, the Q198V mutationhas a negligible effect on the electronic properties of the targetedbacteriochlorophyll a pigment. Instead, the electronicproperties of several other pigments respond to this mutation. Themolecular modeling demonstrates that a single-point mutation can inducelong-range effects on the protein structure, while extensive structuralchanges near a pigment do not necessarily lead to significant changesin the electronic properties of that pigment.

Automated summary

Multiscale molecular modeling is used to predict the optical absorption and circular dichroism spectra of two single-point mutants of the Fenna-Matthews-Olson photosynthetic pigment-protein complex. The modeling approach combines classical molecular dynamics simulations, structural refinement of photosynthetic pigments, and calculations of their excited states in a polarizable protein environment. The modeling demonstrates that a single-point mutation can induce long-range effects on the protein structure and that extensive structural changes near a pigment do not necessarily lead to significant changes in the electronic properties of that pigment.