Time-Resolved Fluorescence Anisotropy from Single Molecules for Characterizing Local Flexibility in Biomolecules.

Area of Science:

• Biophysics
• Molecular Biology
• Structural Biology

Background:

• The forkhead (FKH) domain of the FoxP1 transcription factor plays a critical role in gene regulation.
• FoxP1 dimerization involves a three-dimensional domain-swapping (3D-DS) mechanism, forming a disordered intermediate.
• Understanding the dynamics of intrinsically disordered regions is essential for deciphering FoxP1's function.

Purpose of the Study:

• To establish a protocol for time-resolved single-molecule fluorescence anisotropy (smFA) measurements.
• To investigate the local flexibility and dynamics of the DNA-binding FKH domain of FoxP1.
• To correlate molecular dynamics with FoxP1 dimerization and DNA binding.

Main Methods:

• Utilized confocal microscopy for single-molecule fluorescence anisotropy (smFA) experiments.
• Employed dynamic anisotropy Photon Distribution Analysis (daPDA) and time-resolved anisotropy Burst Variance Analysis (traBVA).
• Developed a step-by-step protocol focusing on time-resolved analyses, variance, and probability distribution techniques.

Main Results:

• Successfully probed local flexibility and dynamics of the FoxP1 FKH domain at the single-molecule level.
• Captured structural dynamics across various timescales using advanced data analysis methods.
• Established a link between molecular dynamics, heterogeneity, and FoxP1's interaction with DNA and dimerization.

Conclusions:

• The developed smFA protocol offers a robust method for studying protein dynamics.
• Insights into FoxP1's complex action mechanism, including dimerization and DNA binding, were gained.
• The study highlights the importance of dynamics in understanding transcription factor function.