Tracking down protein-protein interactions via a FRET-system using site-specific thiol-labeling.

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Förster resonance energy transfer (FRET) is a key technique for studying protein-protein interactions.
• Site-specific protein labeling traditionally requires complex protein engineering.
• Chemical methods offer an alternative for precise fluorescent labeling.

Purpose of the Study:

• To develop and utilize a novel heterobifunctional tag for site-specific protein labeling.
• To explore protein-protein interactions using Förster resonance energy transfer (FRET).
• To quantify the binding affinities of protein-protein and peptide-protein interactions.

Main Methods:

• Synthesis of a heterobifunctional tag with an oxadiazole-methylsulfonyl warhead.
• Bioorthogonal labeling of mitogen-activated protein kinase (MAPK14) and mitogen-activated protein kinase activated kinase (MAPKAP2) or its peptide fragment with FRET pairs.
• Measurement of FRET signals to confirm interactions and estimate dissociation constants.

Main Results:

• The heterobifunctional tag enabled selective, site-specific fluorescent labeling of proteins.
• Strong FRET signals were observed, confirming specific interactions between MAPK14 and MAPKAP2 or its peptide.
• Dissociation constants were determined for protein-protein (145 nM) and peptide-protein (240 nM) interactions.

Conclusions:

• The developed chemical labeling strategy is effective for studying protein-protein interactions.
• This approach provides a valuable alternative to protein engineering for FRET-based interaction studies.
• Accurate binding affinities can be determined for biomolecular interactions using this method.