A Protocol for Studying Transcription Factor Dynamics Using Fast Single-Particle Tracking and Spot-On Model-Based...

Area of Science:

• Cellular and Molecular Biology
• Biophysics
• Biochemistry

Background:

• Single-particle tracking (SPT) is crucial for studying protein diffusion dynamics in living cells.
• Quantifying nuclear protein dynamics, particularly transcription factors (TFs), is essential for understanding gene regulation.
• Existing methods require optimization for high-resolution tracking of fast-moving molecules.

Purpose of the Study:

• To provide a comprehensive protocol for conducting and analyzing fast single-particle tracking (fastSPT) experiments.
• To focus on the dynamics of transcription factors (TFs) within mammalian cells.
• To enable accurate extraction of kinetic parameters from single-particle trajectories.

Main Methods:

• Cell engineering and preparation for SPT experiments.
• Optimization of SPT imaging: low cell density and stroboscopic excitation to minimize errors and motion blur.
• Conversion of raw SPT data into single-particle trajectories and kinetic analysis using the Spot-On package.

Main Results:

• A detailed workflow for fastSPT experiments on transcription factors (TFs) in mammalian cells.
• Methodology for minimizing tracking errors and motion blur during live-cell imaging.
• Demonstration of kinetic modeling using Spot-On to determine TF diffusion coefficients and binding fractions.

Conclusions:

• The presented fastSPT protocol offers a robust approach for dissecting TF dynamics in living cells.
• Accurate kinetic modeling provides insights into the functional states (bound vs. free diffusion) of TFs.
• This method advances the quantitative understanding of gene regulation mechanisms at the single-molecule level.