Bright blue protein

SANTA BARBARA, Calif.—Despite the popularity of methods relying on fluorescent proteins like GFP, the development of these techniques is being hampered by the low quantum yield and rapid photobleaching properties of many of these proteins. Researchers at University of California, Santa Barbara and Pasadena's Caltech are trying to change this, however.

 

As reported in Nature Biotechnology, the scientists used structure-guided design and fluorescence activated cell sorting to create and identify improved versions of blue fluorescent protein (BFP). Of the 330,000 unique sequences they generated, the researchers isolated 20 colonies for further characterization. They found that many of the clones carried mutation known to improve brightness in other fluorescent proteins, but they also identified novel mutations.

 

They then selected two clones with particularly enhanced brightness and found that one, which they named Azurite, had a significantly higher quantum yield than the parental BFP. And when they expressed Azurite in mammalian cells at 37°C, they noted its photobleaching half-life improved 40-fold over BFP, making it particularly well suited for a variety of fluorescence-based screening methods.