A fluorescence resonance energy transfer-based method for histone methyltransferases.

Area of Science:

• Biochemistry
• Enzymology
• Epigenetics

Background:

• Methyltransferases play critical roles in epigenetic modifications, influencing gene expression.
• Accurate assays are needed to study methyltransferase kinetics and inhibition.
• EHMT1 and EHMT2 are key histone methyltransferases involved in cellular processes.

Purpose of the Study:

• To develop a novel and simple fluorescence resonance energy transfer (FRET)-based assay for methyltransferases.
• To utilize the assay for determining kinetic parameters and inhibitory activity of EHMT1 and EHMT2.
• To establish a reliable method for screening methyltransferase inhibitors.

Main Methods:

• A dye-quencher FRET assay was designed using peptides mimicking the histone H3 tail.
• Peptides were functionalized with a dye and a quencher at opposite ends.
• Enzyme activity was detected by monitoring changes in fluorescent intensity upon methylation and subsequent protease cleavage.

Main Results:

• The FRET assay successfully detected methylation of lysine-9 residues on histone H3 peptides.
• Methylated peptides were protected from endoproteinase-EndoLysC cleavage, while unmethylated peptides were cleaved.
• This differential cleavage resulted in a measurable increase in fluorescent intensity, correlating with enzyme activity.
• The assay allowed for the determination of kinetic parameters and inhibitory effects on EHMT1 and EHMT2.

Conclusions:

• A simple and effective FRET-based assay for methyltransferase activity has been established.
• The assay provides a robust platform for kinetic analysis and inhibitor screening of EHMT1 and EHMT2.
• This method offers a valuable tool for epigenetic research and drug discovery targeting methyltransferases.