title: The E1 mechanism in photo-induced beta-elimination reactions for green-to-red conversion of fluorescent proteins.
abstract: KikGR is a fluorescent protein engineered to display green-to-red photoconvertibility that is induced by irradiation with ultraviolet or violet light. Similar to Kaede and EosFP, two naturally occurring photoconvertible proteins, KikGR contains a His(62)-Tyr(63)-Gly(64) tripeptide sequence, which forms a green chromophore that can be photoconverted to a red one via formal beta-elimination and subsequent extension of a pi-conjugated system. Using a crystallizable variant of KikGR, we determined the structures of both the green and red state at 1.55 A resolution. The double bond between His(62)-C(alpha) and His(62)-C(beta) in the red chromophore is in a cis configuration, indicating that rotation along the His(62) C(alpha)-C(beta) bond occurs following cleavage of the His(62) N(alpha)-C(alpha) bond. This structural rearrangement provides evidence that the beta-elimination reaction governing the green-to-red photoconversion of KikGR follows an E1 (elimination, unimolecular) mechanism.
authors: Brain Science Institute, RIKEN, Hirosawa, Wako-city, Saitama, Japan.
authors: Hidekazu
authors: H
authors: Tsutsui
authors: Hideaki
authors: H
authors: Shimizu
authors: Hideaki
authors: H
authors: Mizuno
authors: Nobuyuki
authors: N
authors: Nukina
authors: Toshiaki
authors: T
authors: Furuta
authors: Atsushi
authors: A
authors: Miyawaki
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008164:Luminescent Proteins / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects; D008969:Molecular Sequence Data; D055668:Photochemical Processes; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D014466:Ultraviolet Rays
chemical_list: C513582:Kaede protein, Trachyphyllia geoffroyi; D008164:Luminescent Proteins; D011994:Recombinant Proteins