Light-induced molecular cutting: localized reaction on a single DNA molecule

Area of Science:

• Molecular Biology
• Biochemistry
• Optogenetics

Background:

• Restriction enzymes are crucial tools for DNA manipulation.
• Controlling enzyme activity at the single-molecule level presents significant challenges.
• Existing methods lack spatial precision for targeted DNA modification.

Purpose of the Study:

• To develop a method for optically controlled DNA cutting using restriction enzymes.
• To investigate the spatial and temporal control of enzymatic activity on single DNA molecules.
• To explore applications in single-molecule kinetics and DNA analysis.

Main Methods:

• Stretching lambda-phage DNA molecules.
• Using caged magnesium ions (DM-Nitrophen complex) and EDTA.
• Applying a focused UV light pulse to release magnesium ions and activate the restriction enzyme (Sma 1) locally.
• Varying the ratio of chelating agent to magnesium ions to control the reaction zone radius.

Main Results:

• Selective cutting of lambda DNA at specific restriction sites using a localized light pulse.
• Demonstrated control over the reaction zone size (approx. 6 microm) by adjusting ion concentrations.
• Showcased the enzyme's dependence on magnesium ions for activity.

Conclusions:

• Optically triggered release of magnesium ions provides precise spatial control over restriction enzyme activity.
• This technique allows for localized DNA modification at the single-molecule level.
• Potential applications include studying single-molecule enzymatic kinetics and developing advanced genotyping and sequencing devices.