# Absence of selection for quantum coherence in the Fenna-Matthews-Olson complex: a combined evolutionary and excitonic study

## TL;DR

This study investigates the evolution of the Fenna-Matthews-Olson complex to determine if quantum coherence was selected for, finding no significant evidence of selection for coherence or transport efficiency improvements over time.

## Contribution

It combines evolutionary reconstruction and excitonic analysis to assess whether quantum coherence in the complex was an adaptive trait.

## Key findings

- Mutations were mostly thermodynamically neutral.
- No significant change in exciton transport efficiency over evolution.
- Quantum coherence was not specifically selected for.

## Abstract

We present a study on the evolution of the Fenna-Matthews-Olson bacterial photosynthetic pigment-protein complex. This protein complex functions as an antenna. It transports absorbed photons - excitons - to a reaction center where photosynthetic reactions initiate. The efficiency of exciton transport is therefore fundamental for the photosynthetic bacterium's survival. We have reconstructed an ancestor of the complex to establish whether coherence in the exciton transport was selected for or optimized over time. We have also investigated on the role of optimizing free energy variation upon folding in evolution. We studied whether mutations which connect the ancestor to current day species were stabilizing or destabilizing from a thermodynamic view point. From this study, we established that most of these mutations were thermodynamically neutral. Furthermore, we did not see a large change in exciton transport efficiency or coherence and thus our results predict that exciton coherence was not specifically selected for.