Structural characterization of acylimine-containing blue and red chromophores in mTagBFP and TagRFP fluorescent proteins.
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.
Subach
Oksana M
OM
Department of Anatomy and Structural Biology and Gruss-Lipper Biophotonics Center, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY10461, USA.
Malashkevich
Vladimir N
VN
Zencheck
Wendy D
WD
Morozova
Kateryna S
KS
Piatkevich
Kiryl D
KD
Almo
Steven C
SC
Verkhusha
Vladislav V
VV
D018360:Crystallography, X-Ray; D008164:Luminescent Proteins / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D000097573:Red Fluorescent Protein
D008164:Luminescent Proteins; D000097573:Red Fluorescent Protein