Angular Optical Trapping to Directly Measure DNA Torsional Mechanics

Area of Science:

• Biophysics
• Molecular Biology
• Nanotechnology

Background:

• Angular optical trapping (AOT) offers simultaneous measurement of torque, rotation, position, and force.
• Investigating torsional properties of nucleic acids and DNA-protein complexes is crucial for understanding biological processes.

Purpose of the Study:

• To provide a detailed guide on the principle, construction, and calibration of AOT.
• To enable researchers to perform single-molecule torque measurements on DNA molecules.

Main Methods:

• Detailed description of the AOT technique.
• Inclusion of the constant-force method for torque measurements.
• Introduction of a novel constant-extension method for twist persistence length measurement of DNA.

Main Results:

• The described AOT methods allow precise measurement of DNA torsional properties.
• The constant-extension method facilitates measurement of twist persistence length in both extended and plectonemic DNA configurations.
• The technique is applicable to DNA under extremely low force conditions.

Conclusions:

• AOT is a versatile tool for investigating DNA mechanics and its role in biological functions.
• The provided guide and methods empower researchers in the single-molecule field to implement and utilize AOT.
• This work enhances the understanding of torsional stress impacts on DNA and related biological processes.