Measuring DNA Hybridization Kinetics in Live Cells Using a Time-Resolved 3D Single-Molecule Tracking Method.

Area of Science:

• Molecular Biology
• Biophysics
• Cellular Dynamics

Background:

• Single-molecule detection offers direct kinetic analysis of nucleic acids.
• Current methods lack native cellular context, limiting biological relevance.
• Understanding DNA dynamics in vivo is crucial for cellular processes.

Purpose of the Study:

• To develop and apply a method for tracking individual DNA molecules within mammalian cells.
• To observe and quantify annealing and melting events of DNA in a native cellular environment.
• To compare in vivo DNA hybridization kinetics with in vitro measurements.

Main Methods:

• Integrated 3D single-molecule tracking and lifetime measurement.
• Following individual DNA molecules diffusing within live mammalian cells.
• Observing multiple annealing and melting events on the same DNA molecules.

Main Results:

• Successfully tracked individual DNA molecules and their dynamic events in vivo.
• Demonstrated the ability to observe multiple annealing/melting cycles on single DNA molecules.
• Found 13- to 163-fold higher association constants for DNA hybridization in cellular environments compared to in vitro.

Conclusions:

• The developed method enables in-depth study of nucleic acid dynamics within living cells.
• The cellular environment significantly enhances DNA hybridization kinetics.
• This finding has implications for understanding DNA-related processes in vivo.