title: Synthesis and spectral and chemical properties of the yellow fluorescent protein zFP538 chromophore.
abstract: Members of the green fluorescent protein (GFP) family become chromophoric through a unique pathway based on autocatalytic modifications of their amino acid residues. The yellow fluorescent protein zFP538 from the button polyp Zoanthus possesses unique spectral characteristics that are intermediate between those of the green and orange-red fluorescent proteins. In this study, we used chemical synthesis to resolve conflicting data from crystallographic and biochemical analyses of the zFP538 chromophore structure. We synthesized 2-(5-amino-1-oxopentyl)-5-(4-hydroxybenzylidene)-3-methyl-3,5-dihydro-4H-imidazol-4-one (5), which can spontaneously react intramolecularly to form cyclic imine (7). Compound 7 represents the native chromophore structure reported in the crystallographic study. We have also discovered an unusual isomerization of a 2-acylimidazolone to a 2,6-diketopiperazine derivative. The zFP538 chromophore is a complex system with intriguing chemical and spectral behavior, properties that have led to discrepancies in the interpretation of its structure. Our study supports the findings of previous crystallographic work, which postulated a cyclic imine chromophore structure within the native zFP538 protein, and also provides an explanation for experimental results obtained in the biochemical characterization of zFP538-derived chromopeptides.
authors.affiliation: Shemiakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, Moscow 117997, Russia.
authors.forename: Ilia V
authors.initials: IV
authors.lastname: Yampolsky
authors.forename: Tamara A
authors.initials: TA
authors.lastname: Balashova
authors.forename: Konstantin A
authors.initials: KA
authors.lastname: Lukyanov
mesh_terms: D000818:Animals; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000138:chemical synthesis* / Q000378:metabolism; D008164:Luminescent Proteins / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism; D011489:Protein Denaturation; D012615:Sea Anemones; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D013056:Spectrophotometry, Ultraviolet; D000097573:Red Fluorescent Protein
chemical_list: D005456:Fluorescent Dyes; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D010455:Peptides; D000097573:Red Fluorescent Protein