Cooperative Vinculin Binding to Talin Mapped by Time-Resolved Super Resolution Microscopy

Area of Science:

• Cell Biology
• Biophysics

Background:

• Focal adhesions are crucial for cell adhesion and migration.
• Talin is a key dimeric protein in focal adhesions, with cryptic binding sites exposed upon unfolding.

Purpose of the Study:

• To investigate the in situ dynamics of talin dimer stretching.
• To determine the structural changes in talin that lead to vinculin binding.
• To understand the mechanism of vinculin recruitment to talin.

Main Methods:

• Developed a novel method to monitor talin dimer stretch dynamics in situ.
• Utilized vinculin tagged with DHFR-TMP Atto655 for binding studies.
• Measured the separation of talin N-termini and C-terminal domains during stretching.

Main Results:

• Talin N-termini separated by 162 ± 44 nm on average, while C-terminal domains colocalized.
• Optimal vinculin and vinculin head binding occurred when talin was stretched to 180 nm.
• Multiple vinculins bound rapidly and cooperatively to localized regions of the talin rod during stretching.

Conclusions:

• Talin likely stretches as an antiparallel dimer.
• Talin stretching activates vinculin binding in a cooperative manner.
• This mechanism may involve stabilization of folded talin by other binding proteins.