Engineered metal binding sites on green fluorescence protein

The ability to assay a variety of metals by noninvasive methods has applica tions in both biomedical and environmental research. Green fluorescent prot ein (GFP) is a protein isolated from coelenterates that exhibits spontaneou s fluorescence. GFP does not require any exogenous cofactors for fluorescen ce, and can be easily appended to other proteins at the DNA level, producin g a fluorescence-labeled target protein in vivo. Metals in close proximity to chromophores are known to quench fluorescence in a distance-dependent fa shion. Potential metal binding sites on the surface of GFP have been identi fied and mutant proteins have been designed, created, and characterized. Th ese metal-binding mutants of GFP exhibit fluorescence quenching at lower tr ansition metal ion concentrations than those of the wild-type protein. Thes e GFP mutants represent a new class of protein-based metal sensors. (C) 200 0 Academic Press.