title: The 1.7 A crystal structure of Dronpa: a photoswitchable green fluorescent protein.
abstract: The green fluorescent protein (GFP), its variants, and the closely related GFP-like proteins possess a wide variety of spectral properties that are of widespread interest as biological tools. One desirable spectral property, termed photoswitching, involves the light-induced alteration of the optical properties of certain GFP members. Although the structural basis of both reversible and irreversible photoswitching events have begun to be unraveled, the mechanisms resulting in reversible photoswitching are less clear. A novel GFP-like protein, Dronpa, was identified to have remarkable light-induced photoswitching properties, maintaining an almost perfect reversible photochromic behavior with a high fluorescence to dark state ratio. We have crystallized and subsequently determined to 1.7 A resolution the crystal structure of the fluorescent state of Dronpa. The chromophore was observed to be in its anionic form, adopting a cis co-planar conformation. Comparative structural analysis of non-photoactivatable and photoactivatable GFPs, together with site-directed mutagenesis of a position (Cys62) within the Dronpa chromophore, has provided a basis for understanding Dronpa photoactivation. Specifically, we propose a model of reversible photoactivation whereby irradiation with light leads to subtle conformational changes within and around the environment of the chromophore that promotes proton transfer along an intricate polar network.
authors.affiliation: The Protein Crystallography Unit, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Pascal G
authors.initials: PG
authors.lastname: Wilmann
authors.forename: Kristina
authors.initials: K
authors.lastname: Turcic
authors.forename: Jion M
authors.initials: JM
authors.lastname: Battad
authors.forename: Matthew C J
authors.initials: MC
authors.lastname: Wilce
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Devenish
authors.forename: Mark
authors.initials: M
authors.lastname: Prescott
authors.forename: Jamie
authors.initials: J
authors.lastname: Rossjohn
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D005453:Fluorescence; D049452:Green Fluorescent Proteins / Q000737:chemistry* / Q000235:genetics; D008027:Light; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010777:Photochemistry; D011487:Protein Conformation
chemical_list: D049452:Green Fluorescent Proteins