Ancestral Protein-Based Lighting.

Protein-optoelectronics is a paradigm toward eco-designed and sustainable technologies. The challenge is, however, how to preserve the native activity of proteins upon device fabrication/operation in non-native environments (solvents, organic/inorganic interfaces, and working temperatures/irradiations). Herein, a new vision to identify and design ancestral-like fluorescent proteins (FPs) is proposed. Using ancestral sequence reconstruction (ASR) out of a large dataset (221) of the best modern FPs suitable for photon down-conversion in bio-hybrid light-emitting diodes (Bio-HLEDs) a historical-genetic reconstruction (family tree) was obtained, identifying a possible common ancestral FP. This computationally designed protein is produced in bacteria, featuring outstanding photoluminescence quantum yields in solution (e.g., 90%/80% for green-/red-emitting forms) and a strong tendency to agglomerate in polymer coatings. This resulted in red-emitting Bio-HLEDs that outperformed the reference with ≈2-fold enhanced stabilities. The resplendent green-/red-emission of ancestral-like FP itself and its respective devices led us to coin this new protein as QuetzalFP. Overall, it is set in ASR as an effective concept to reshape protein-optoelectronics allowing us to identify i) many interesting ancestral FPs for lighting and ii) QuetzalFP as stepping-stone platform for protein engineering.