Light-dependent regulation of structural flexibility in a photochromic fluorescent protein.
The structural basis for the photochromism in the fluorescent protein Dronpa is poorly understood, because the crystal structures of the bright state of the protein did not provide an answer to the mechanism of the photochromism, and structural determination of the dark state has been elusive. We performed NMR analyses of Dronpa in solution at ambient temperatures to find structural flexibility of the protein in the dark state. Light-induced changes in interactions between the chromophore and beta-barrel are responsible for switching between the two states. In the bright state, the apex of the chromophore tethers to the barrel by a hydrogen bond, and an imidazole ring protruding from the barrel stabilizes the plane of the chromophore. These interactions are disrupted by strong illumination with blue light, and the chromophore, together with a part of the beta-barrel, becomes flexible, leading to a nonradiative decay process.
Mizuno
Hideaki
H
Cell Function and Dynamics, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-City, Saitama 351-0198, Japan.
Mal
Tapas Kumar
TK
Wälchli
Markus
M
Kikuchi
Akihiro
A
Fukano
Takashi
T
Ando
Ryoko
R
Jeyakanthan
Jeyaraman
J
Taka
Junichiro
J
Shiro
Yoshitsugu
Y
Ikura
Mitsuhiko
M
Miyawaki
Atsushi
A
D000595:Amino Acid Sequence; D000818:Animals; D037421:Anthozoa / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008027:Light; D008164:Luminescent Proteins / Q000737:chemistry* / Q000528:radiation effects*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D018583:Pliability / Q000528:radiation effects; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D013696:Temperature
D008164:Luminescent Proteins