Green Fluorescent Protein Mutant Forms A Red Chromophore

Scientists have created the first red mutant of the jellyfish green fluorescent protein (GFP), a widely used biological marker (Biochemistry, DOI: 10.1021/bi702130s). Although red fluorescent proteins for cellular labeling are available from other organisms, the ease of expressing GFP in any organism makes a red GFP mutant desirable.

A research team led by Vladislav V. Verkhusha of Albert Einstein College of Medicine, in New York City, and Konstantin A. Lukyanov of the Shemiakin-Ovchinnikov Institute of Bioorganic Chemistry, in Moscow, found red GFP mutants following multiple rounds of random mutagenesis and high-throughput screening. The key to the researchers’ success, Verkhusha says, is that they started with blue GFP mutants rather than green mutants.

The structure of the brightest red fluorescent mutant protein is shown, with the amino acids of the chromophore highlighted. This protein only partially matures into a red chromophore, meaning that it emits both red and green light.

“This mutant is the first step toward the ideal monomeric red fluorescent protein,” Verkhusha says. “We plan to continue our work to make the mutant absolutely red without any green component.”