Unbinding Kinetics of Syndecans by Single-Molecule Force Spectroscopy

Area of Science:

• Biochemistry
• Cell Biology
• Biophysics

Background:

• Syndecans are transmembrane proteoglycans regulating cell-extracellular matrix interactions.
• Integrins and syndecans cooperate to control cell adhesion.
• Specific extracellular matrix binding is determined by syndecan glycosaminoglycan chains.

Purpose of the Study:

• To investigate the force-induced unbinding kinetics of single syndecan complexes.
• To determine if unbinding pathways differ between syndecan family members.
• To correlate unbinding mechanisms with syndecan chain structures.

Main Methods:

• Atomic force microscopy (AFM) force spectroscopy was employed to measure unbinding forces.
• Data were analyzed using the Bell-Evans and Dudko-Hummer-Szabo theoretical models.
• Single-molecule force spectroscopy was used to probe unbinding events.

Main Results:

• Distinct unbinding pathways were observed for different syndecan family members.
• Syndecan-1 unbinding involves two energy barriers (inner and outer).
• Syndecan-4 unbinding occurs over a single energy barrier.

Conclusions:

• Single syndecan complex unbinding is dependent on the specific syndecan family member.
• Differences in heparan and chondroitin chain structures likely dictate distinct unbinding pathways.
• These findings offer new insights into the mechanical regulation of cell-matrix adhesion.