Yellow and Orange Fluorescent Proteins with Tryptophan-based Chromophores

Rapid development of new microscopy technicques exposed the heed for genetically encoded fluorescent tags with special properties. Recent works demonstrated the potential of fluorescent proteins with tryptophan-based chromophores We applied rational design and random mutagenesis to the monomeric red fluorescent protein FusionRed and found two groups of mutants carrying a tryptophan-teased chromophore: with yellow (535 nm) or orange (565 nm) emission. On the basis of the properties of proteins, a model synthetic chromophore, and a computational modeling, we concluded that the presence of a ketone-containing chromophore in different isomeric forms can explain the observed yellow and orange phenotypes.