Design of Ctenophore Ca2+-Regulated Photoprotein Berovin Capable of Being Converted into Active Protein Under Physiological Conditions: Computational and Experimental Approaches

Here, we describe (1) the AlphaFold-based structural modeling approach to identify amino acids of the photoprotein berovin that are crucial for coelenterazine binding, and (2) the production and characterization of berovin mutants with substitutions of the identified residues regarding their effects on the ability to form an active photoprotein under physiological conditions and stability to light irradiation. The combination of mutations K90M, N107S, and W103F is demonstrated to cause a shift of optimal conditions for the conversion of apo-berovin into active photoprotein towards near-neutral pH and low ionic strength, and to reduce the sensitivity of active berovin to light. According to the berovin spatial structure model, these residues are found in close proximity to the 6-(<i>p</i>-hydroxy)-phenyl group of the coelenterazine peroxyanion.