Site-Selective Lysine Reactions Guided by Protein-Peptide Interaction

Area of Science:

• Biochemistry
• Chemical Biology
• Molecular Biology

Background:

• Site-selective post-translational modifications of lysine residues are crucial for cellular signaling.
• Achieving site selectivity in non-enzymatic protein reactions remains a significant challenge due to similar chemical reactivities of lysine groups.
• Differentiating and targeting specific lysine residues among multiple lysines and the N-terminal amine is difficult.

Purpose of the Study:

• To explore and validate a novel peptide-guided strategy for proximal lysine conjugation reactions.
• To achieve site-specific targeting of single lysine ε-amino groups in natural proteins with multiple lysine residues.
• To demonstrate the feasibility and optimize amine reactions for site-selective lysine modification.

Main Methods:

• Utilized peptide-guided fluorodinitrobenzene, isothiocyanate, and phenyl ester reactions.
• Investigated proximity-induced reactivity driven by specific protein-peptide interactions.
• Tested the method on an SH3 domain and ubiquitin-like proteins (SUMO, Atg8 family, LC3).
• Confirmed reaction sites using mass spectrometry.

Main Results:

• Successfully demonstrated site-specific targeting of single lysine ε-amino groups in proteins with multiple lysine residues.
• Achieved exquisite site selectivity in SH3 domain and various ubiquitin-like proteins.
• Validated the feasibility of selected amine-reactive groups for site-selective lysine reactions.
• Optimized reaction conditions and confirmed specific modification sites on LC3 protein.

Conclusions:

• Peptide-guided reactions enable precise, site-selective modification of single lysine residues in proteins.
• This approach overcomes the challenge of differentiating reactive amine groups in complex protein environments.
• The validated method offers a powerful tool for controlling cellular signaling events through targeted protein modification.