Tracking DOT1L methyltransferase activity by stable isotope labelling using a selective synthetic co-factor.

Area of Science:

• Biochemistry
• Molecular Biology
• Epigenetics

Background:

• Epigenetic processes regulate gene expression without altering DNA sequence.
• Epigenetic marks include DNA modifications and protein post-translational modifications (PTMs).
• Histone methylation is a key epigenetic marker controlling gene expression, but studying specific methyltransferases is challenging due to functional redundancy.

Purpose of the Study:

• To develop a method for tracking the activity of specific histone methyltransferases.
• To enable the study of individual methyltransferase functions in epigenetic regulation.

Main Methods:

• Development of an isotopically labeled analogue of S-adenosyl-L-methionine (¹³CD₃-BrSAM).
• Utilizing mass spectrometry (MS) to detect and quantify methylation activity.
• Achieving selectivity for the histone lysine methyltransferase DOT1L.

Main Results:

• The developed ¹³CD₃-BrSAM analogue allows for the specific tracking of DOT1L methylation activity.
• Mass spectrometry successfully detected the isotopic label, enabling quantitative analysis of methylation.
• Demonstrated a novel approach to link PTM discovery with specific enzymatic mediators.

Conclusions:

• The ¹³CD₃-BrSAM tool provides a method to study specific methyltransferase activity.
• This approach can be extended to investigate other methyltransferases and their roles in biological processes.
• Facilitates a deeper understanding of the enzymatic basis of epigenetic regulation.