Specific DNA-protein interactions on mica investigated by atomic force microscopy

Area of Science:

• Nanobiotechnology
• Surface Science
• Molecular Biology

Background:

• Studying DNA processing by site-specific proteins on surfaces is crucial for nanobioscience and atomic force microscopy (AFM) applications.
• Mica, an atomically flat and negatively charged surface, is commonly used for high-resolution AFM imaging.
• Limited knowledge exists regarding DNA accessibility to enzymes on mica surfaces despite observed DNA/protein interactions via AFM.

Purpose of the Study:

• To investigate the accessibility of adsorbed DNA to restriction endonucleases (EcoRI and EcoRV) on mica surfaces using AFM.
• To understand how varying salt concentrations affect DNA adsorption and subsequent enzymatic cleavage.
• To explore new avenues for studying DNA/protein interactions and surface-based DNA modification using AFM.

Main Methods:

• Utilized atomic force microscopy (AFM) to observe DNA-enzyme interactions on mica.
• Adsorbed DNA onto mica surfaces under different salt concentrations to induce weak and strong binding.
• Assessed the enzymatic cleavage of DNA by restriction endonucleases (EcoRI and EcoRV) on mica.

Main Results:

• DNA adsorption on mica transitions from weak to strong binding with increasing divalent or multivalent salt concentrations.
• Loosely adsorbed DNA on mica surfaces was efficiently cleaved by restriction endonucleases.
• Strongly bound DNA on mica surfaces exhibited inhibited accessibility to enzymatic cleavage.

Conclusions:

• The binding strength of DNA on mica surfaces significantly influences its accessibility to enzymatic cleavage.
• Loosely adsorbed DNA on mica offers a viable substrate for site-specific enzymatic modification.
• These findings provide new perspectives for studying DNA-protein interactions and surface-based DNA manipulation with AFM.