CRYSTAL-STRUCTURE OF THE AEQUOREA-VICTORIA GREEN FLUORESCENT PROTEIN

The green fluorescent protein (GFP) from the Pacific Northwest jellyfi sh Aequorea victoria has generated intense interest as a marker for ge ne expression and localization of gene products, The chromophore, resu lting from the spontaneous cyclization and oxidation of the sequence - Ser(65) (or Thr(65))-Tyr(66)-Gly(67)-, requires the native protein fol d for both formation and fluorescence emission. The structure of Thr(6 5) GFP has been determined at 1.9 angstrom resolution, The protein fol d consists of an 11-stranded beta barrel with a coaxial helix, with th e chromophore forming from the central helix. Directed mutagenesis of one residue adjacent to the chromophore, Thr(203), to Tyr or His resul ts in significantly red-shifted excitation and emission maxima.