Multistage dynamics of Hg²⁺-DNA interactions: a single-molecule study

Area of Science:

• Biochemistry
• Biophysics
• Molecular Biology

Background:

• Metal ion-DNA interactions are crucial for biological processes and technological applications like biosensors.
• Understanding the precise mechanisms of these interactions is essential for advancing DNA-based technologies.

Purpose of the Study:

• To investigate the single-molecule interactions between lambda-DNA (λ-DNA) and mercury (Hg2+) and cadmium (Cd2+) ions.
• To elucidate the conformational changes and binding dynamics induced by these metal ions under varying conditions.

Main Methods:

• Single-molecule force spectroscopy using magnetic tweezers.
• Atomic Force Microscopy (AFM) for structural analysis.

Main Results:

• Both Hg2+ and Cd2+ ions induced significant DNA compaction, influenced by ion concentration and applied force.
• Hg2+ exhibited complex, multi-stage compaction dynamics, including two-stage and three-stage processes under different force and concentration conditions.
• Cd2+ binding to DNA displayed a distinct stepwise pattern.
• Hg2+ demonstrated a more pronounced influence on DNA conformation compared to Cd2+.

Conclusions:

• The distinct dynamics suggest different binding mechanisms for Hg2+ and Cd2+ with DNA, potentially involving mismatched base-pair formation for Hg2+.
• A model was proposed to explain the observed complex dynamics of Hg2+-DNA interactions.