Synthesis and spectral and chemical properties of the yellow fluorescent protein zFP538 chromophore

Biochemistry. 2009 Aug 25;48(33):8077-82. doi: 10.1021/bi900719x.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Fluorescent Dyes / chemical synthesis
  • Fluorescent Dyes / metabolism
  • Green Fluorescent Proteins / chemical synthesis*
  • Green Fluorescent Proteins / metabolism
  • Luminescent Proteins / chemistry
  • Magnetic Resonance Spectroscopy
  • Peptides / chemical synthesis
  • Peptides / metabolism
  • Protein Denaturation
  • Sea Anemones
  • Spectrometry, Fluorescence
  • Spectrometry, Mass, Electrospray Ionization
  • Spectrophotometry, Ultraviolet

Substances

  • Fluorescent Dyes
  • Luminescent Proteins
  • Peptides
  • red fluorescent protein
  • Green Fluorescent Proteins