Persistence length measurements from stochastic single-microtubule trajectories

Area of Science:

• Biophysics
• Cell Biology
• Polymer Physics

Background:

• Microtubules are crucial cytoskeletal polymers involved in intracellular transport.
• Understanding microtubule dynamics and mechanical properties is essential for cell biology.
• Quantifying the stiffness of microtubule ends informs their function in processes like cell division.

Purpose of the Study:

• To present a straightforward method for determining the persistence length of microtubule ends.
• To establish that a single microtubule trajectory is sufficient for reliable measurement.
• To quantify the persistence length of microtubule tips moving on kinesin surfaces.

Main Methods:

• Analyzing stochastic trajectories of microtubules on kinesin-coated surfaces.
• Modeling microtubule tip movement as a random walk based on tangent angle variance.
• Calculating persistence length from the variance of the tangent trajectory angle of individual microtubules.

Main Results:

• The tangent angle variance of microtubule trajectories directly correlates with persistence length.
• A reliable persistence length value can be obtained from a single microtubule trajectory.
• The average persistence length of microtubule tips was determined to be 0.24 ± 0.03 mm.

Conclusions:

• The developed method offers a simple and effective way to measure microtubule persistence length.
• This technique advances the understanding of microtubule mechanical properties at the nanoscale.
• The findings provide valuable data for biophysical models of microtubule-kinesin interactions.