Probing the Conformational Landscape of DNA Polymerases Using Diffusion-Based Single-Molecule FRET

Area of Science:

• Biochemistry
• Molecular Biology
• Biophysics

Background:

• DNA polymerases are crucial enzymes for DNA replication and repair.
• Nucleotide selection fidelity is essential to prevent mutations.
• Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for studying enzyme dynamics.

Purpose of the Study:

• To identify and characterize conformational states of DNA polymerases during nucleotide selection.
• To investigate the role of a partially closed conformation in fidelity.
• To provide a comprehensive overview of smFRET methods for DNA polymerase analysis.

Main Methods:

• Utilized doubly labeled variants of Escherichia coli DNA polymerase I.
• Employed solution-based single-molecule fluorescence data acquisition.
• Developed strategies for protein labeling and data analysis.

Main Results:

• Identified and characterized a partially closed DNA polymerase conformation.
• Demonstrated this partially closed state acts as a primary checkpoint for nucleotide selection.
• Analyzed conformational changes in wild-type and low-fidelity DNA polymerase derivatives.

Conclusions:

• A partially closed conformation is a key determinant of DNA polymerase fidelity.
• smFRET assays are effective for dissecting enzyme mechanisms at the single-molecule level.
• The described methods can be applied to study DNA polymerases in vitro and in vivo.