title: Structural characterization of acylimine-containing blue and red chromophores in mTagBFP and TagRFP fluorescent proteins.
abstract: We determined the 2.2 A crystal structures of the red fluorescent protein TagRFP and its derivative, the blue fluorescent protein mTagBFP. The crystallographic analysis is consistent with a model in which TagRFP has the trans coplanar anionic chromophore with the conjugated pi-electron system, similar to that of DsRed-like chromophores. Refined conformation of mTagBFP suggests the presence of an N-acylimine functionality in its chromophore and single C(alpha)-C(beta) bond in the Tyr64 side chain. Mass spectrum of mTagBFP chromophore-bearing peptide indicates a loss of 20 Da upon maturation, whereas tandem mass spectrometry reveals that the C(alpha)-N bond in Leu63 is oxidized. These data indicate that mTagBFP has a new type of the chromophore, N-[(5-hydroxy-1H-imidazole-2-yl)methylidene]acetamide. We propose a chemical mechanism in which the DsRed-like chromophore is formed via the mTagBFP-like blue intermediate.
authors.affiliation: Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY10461, USA.
authors.forename: Oksana M
authors.initials: OM
authors.lastname: Subach
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Malashkevich
authors.forename: Wendy D
authors.initials: WD
authors.lastname: Zencheck
authors.forename: Kateryna S
authors.initials: KS
authors.lastname: Morozova
authors.forename: Kiryl D
authors.initials: KD
authors.lastname: Piatkevich
authors.forename: Steven C
authors.initials: SC
authors.lastname: Almo
authors.forename: Vladislav V
authors.initials: VV
authors.lastname: Verkhusha
mesh_terms: D018360:Crystallography, X-Ray; D008164:Luminescent Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D000097573:Red Fluorescent Protein
chemical_list: D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein