Manipulation of double-stranded DNA melting by force

Area of Science:

• Biophysics
• Computational Biology
• Molecular Dynamics

Background:

• Understanding DNA denaturation is crucial for molecular biology.
• Previous studies focused on thermal denaturation.
• Force-induced DNA unwinding mechanisms require further investigation.

Purpose of the Study:

• To investigate force-induced melting of double-stranded DNA (dsDNA) at finite temperatures.
• To analyze how different force application methods (end unzipping, midunzipping, end shearing) affect DNA denaturation pathways.
• To explore the stabilization of intermediate DNA states, such as bubbles and loops, under mechanical stress.

Main Methods:

• Integration of elasticity (Gaussian network model) with base-pair binding energies.
• Generalization of thermal denaturation models to include force-induced effects.
• Monitoring free-energy landscapes and probability distributions of denaturation intermediates.

Main Results:

• Different force manipulations lead to distinct dominant intermediate states during dsDNA denaturation.
• The stable bubble state observed in thermal denaturation is absent in end unzipping and end shearing.
• Midunzipping or force application near the chain's middle stabilizes similar bubble structures.

Conclusions:

• Force application strategy critically influences DNA denaturation pathways and intermediate states.
• This study provides a method for stabilizing DNA bubbles and loops using targeted force manipulations.
• Findings may offer insights into mechanisms employed by DNA enzymes and motors for DNA opening.