Visualizing protein-DNA interactions in live bacterial cells using photoactivated single-molecule tracking

Area of Science:

• Molecular Biology
• Cellular Processes
• Microscopy Techniques

Background:

• Protein-DNA interactions are crucial for essential cellular functions like replication and repair.
• Understanding these interactions within living cells remains a challenge.
• Existing in vitro methods provide limited insight into in vivo mechanisms.

Purpose of the Study:

• To introduce and detail a novel method for quantifying DNA-binding protein activity in live Escherichia coli.
• To enable real-time, single-cell level measurement of protein-DNA interactions.
• To provide a framework for analyzing protein activity and substrate abundance.

Main Methods:

• Utilized Photoactivated Localization Microscopy (PALM) for high-resolution imaging.
• Employed single-molecule tracking to monitor protein mobility.
• Quantified DNA-binding events by detecting changes in protein diffusion upon chromosome association.

Main Results:

• The fraction of bound molecules directly correlates with protein activity and substrate availability.
• The method allows for single-cell level quantitative analysis.
• Demonstrated procedures for sample preparation, data acquisition, and analysis.

Conclusions:

• The developed method offers a powerful tool for studying dynamic protein-DNA interactions in vivo.
• This approach advances our understanding of cellular processes governed by DNA-binding proteins.
• Provides a quantitative measure of protein activity and substrate abundance within living bacterial cells.