A selenium-based click AdoMet analogue for versatile substrate labeling with wild-type protein methyltransferases

Area of Science:

• Biochemistry
• Chemical Biology
• Posttranslational Modifications

Background:

• Protein methylation, a key posttranslational modification, is catalyzed by S-adenosyl-L-methionine-dependent protein methyltransferases (MTases).
• Diverse cellular functions are regulated by protein methylation, yet comprehensive methods for identifying MTase substrates are lacking due to broad substrate specificities of some MTases.

Purpose of the Study:

• To synthesize a novel S-adenosyl-L-methionine (AdoMet) analogue for enzymatic propargylation of protein substrates.
• To develop a method for efficient labeling and profiling of protein methyltransferase targets using click chemistry.

Main Methods:

• Synthesis of a selenium-containing AdoMet analogue for enhanced cofactor stability and reactivity.
• Enzymatic transfer of a propargyl group to protein substrates by wild-type MTases.
• Labeling of propargylated proteins via copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry.

Main Results:

• The novel selenium-based AdoMet analogue demonstrated enhanced stability and enzymatic reactivity compared to sulfur-based cofactors.
• A broad spectrum of wild-type protein MTases, including those acting on lysine, arginine, and glutamine residues, accepted the new cofactor.
• Efficient labeling of modified proteins was achieved using CuAAC click chemistry, enabling substrate identification.

Conclusions:

• The developed AdoMet analogue and click chemistry approach provide a powerful tool for comprehensive protein methyltransferase target profiling.
• This method facilitates the study of diverse cellular functions regulated by protein methylation and MTase activity.