A Peptide-Based Ligand-Directed Chemistry Enables Protein Functionalization

Area of Science:

• Biochemistry
• Chemical Biology
• Molecular Biology

Background:

• Site-specific protein modification is crucial for understanding protein function and developing therapeutics.
• Existing methods often require complex protecting groups or lack efficiency.
• Ligand-directed (LD) chemistry offers a promising avenue for targeted protein functionalization.

Purpose of the Study:

• To develop a novel, efficient method for site-specific protein modification using ligand-directed chemistry.
• To investigate the utility of a methionine-appended peptide as a ligand for proximity-induced group transfer.
• To demonstrate the applicability of this method for labeling proteins in living cells.

Main Methods:

• A peptide with an appended methionine (Met) was synthesized and utilized as a ligand.
• The methionine thioether was oxidized to a sulfonium warhead.
• Proximity-induced group transfer was achieved onto protein cysteine residues upon peptide-target binding.
• The method was validated using the model protein PDZ and its ligand peptides.
• Living cell labeling experiments were performed.

Main Results:

• The developed sulfonium warhead could be readily constructed using unprotected peptides.
• Successful proximity-induced group transfer was demonstrated onto protein cysteine residues.
• The method proved effective on the model protein PDZ and its corresponding ligand peptides.
• Efficient site-specific labeling of proteins within living cells was achieved.

Conclusions:

• Ligand-directed chemistry utilizing a methionine-appended peptide and a sulfonium warhead is a powerful tool for site-specific protein modification.
• This approach offers a convenient and efficient method for protein labeling, even in complex biological environments.
• The demonstrated living cell labeling capability highlights the potential of this technique for various biological applications.