Fast Leaps between Millisecond Confinements Govern Ase1 Diffusion along Microtubules

Area of Science:

• Cell Biology
• Biophysics
• Microscopy

Background:

• Protein diffusion is crucial for cellular functions.
• Microtubule-associated proteins (MAPs) play vital roles in cytoskeletal dynamics.
• Real-time experimental observation of protein diffusion on microtubules has been lacking.

Purpose of the Study:

• To experimentally observe and characterize the real-time diffusion of microtubule-associated protein Ase1 along microtubule surfaces.
• To elucidate the mechanism of protein translocation on the microtubule lattice at high resolution.
• To understand the interaction potential between Ase1 and microtubules.

Main Methods:

• Interferometric scattering microscopy (iSCAT) was employed for high-resolution imaging.
• The movement of Ase1 along microtubules was visualized at nanometer and microsecond scales.
• Analysis of diffusion patterns, including confinements and leaps, was performed.

Main Results:

• Direct visualization of Ase1's confined diffusion along microtubule protofilaments.
• Resolution of millisecond-scale dwelling times and fast positional changes.
• The derived interaction potential accurately reflects tubulin-dimer periodicity and microtubule electrostatic potential.

Conclusions:

• Ase1 exhibits a specific mode of diffusive translocation along the periodic surface of microtubules.
• Understanding protein-microtubule interactions is key to regulating cytoskeletal processes.
• This work provides a foundation for studying other MAPs and their roles in cellular functions like cargo trafficking and cell division.