Genetically Encoded Fluorescent Reporters of Histone Methylation in Living Cells

• Published in: Journal of the American Chemical Society Vol. 126; no. 19; pp. 5982 - 5983
• Main Authors: Lin, Chi-Wang, Jao, Cindy Y, Ting, Alice Y
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19.05.2004
• Subjects: Animals; Biological and medical sciences; Cells; Escherichia coli - genetics; Escherichia coli - metabolism; Fluorescent Dyes - chemistry; Fundamental and applied biological sciences. Psychology; Genes, Reporter - genetics; Histones - genetics; Histones - metabolism; Lysine - chemistry; Methylation; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutagenesis. Repair; Paramecium - metabolism; Protein Processing, Post-Translational; Posttranslational modification; Reporter gene; Fluorescent tracer; Mutagenesis; Histone; Methylation; Intramolecular interaction
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja038854h

We report the design and characterization of two genetically encoded fluorescent reporters of histone protein methylation. The reporters are four-part chimeric proteins consisting of a substrate peptide from the N-terminus of histone H3 fused to a chromodomain (a natural methyllysine-specific recognition domain), sandwiched between a fluorescence resonance energy transfer (FRET)-capable pair of fluorophores, cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP). Enzymatic methylation by a methyltransferase induces complexation of the methylated substrate peptide to the chromodomain, changing the FRET level between the flanking CFP and YFP domains. Reporters developed using the chromodomains from HP1 and Polycomb respond to enzymatic methylation at the lysine 9 and lysine 27 positions of histone H3, respectively, giving 60% and 28% YFP/CFP emission ratio increases in vitro or in single living cells. These reporters should be useful for studying gene silencing and X-chromosome inactivation with high spatial and temporal resolution in intact cells and may also aid in the search for conjectured histone demethylase activity.