Waiting Time Distributions in Hybrid Models of Motor-Bead Assays: A Concept and Tool for Inference

Area of Science:

• Biophysics
• Single-molecule biophysics
• Molecular motors

Background:

• Molecular motor dynamics are typically studied indirectly via attached bead movement in motor-bead assays.
• Extracting key motor parameters like step size and stalling force often requires external control, limiting experimental flexibility.

Purpose of the Study:

• To develop a non-invasive method for extracting molecular motor step size and stalling force.
• To enable parameter determination solely from observable bead trajectory data, without external control.

Main Methods:

• A generic hybrid model combining continuous (bead) and discrete (motor) degrees of freedom was used.
• The method relies on analyzing waiting times and transition statistics of the observable bead trajectory.
• Deductions are made without external control parameters, focusing on inherent motor dynamics.

Main Results:

• A method was proposed to extract step size and stalling force from waiting times and transition statistics.
• The approach is demonstrated to be non-invasive and operationally accessible for experiments.
• Results were validated through extensive numerical simulations using parameters from an F1-ATPase assay.

Conclusions:

• The proposed method offers a novel, non-invasive way to characterize molecular motors.
• This technique can be applied to various models of molecular motor dynamics.
• The findings align with recent advances in stochastic thermodynamics for inferring system parameters from observable transitions.