External torque application to molecular motor F₁-ATPase using optical vortex trapping.

Area of Science:

• Biophysics
• Molecular Biology
• Optical Physics

Background:

• Single-molecule manipulation is crucial for understanding biological mechanisms.
• Optical tweezers are widely used but struggle with applying constant torque for rotational motion.
• Measuring torque on moving molecules presents significant challenges.

Purpose of the Study:

• To develop a method for quantitative mechanical manipulation of biomolecules using optical tweezers.
• To enable precise application of constant torque to molecular motors.
• To measure the torque generated by molecular motors.

Main Methods:

• Adaptation of optical tweezers to generate optical vortices (OVs) via phase modulation.
• Utilizing a DNA origami rod as a precise handle for torque application.
• Applying controlled torque to the molecular motor F1-ATPase using OV-equipped optical tweezers.

Main Results:

• Optical vortices enabled quantitative mechanical manipulations with optical tweezers.
• The developed technique allowed for the measurement of torque generated by a molecular motor.
• Constant torque application via OVs successfully stalled and reversed the rotation of F1-ATPase.

Conclusions:

• Optical vortices offer a novel approach for precise torque application in single-molecule studies.
• This technique advances the ability to quantitatively investigate molecular motor function.
• The method is valuable for applying constant torque to various biomolecules.