Development of an Azoreductase-based Reporter System with Synthetic Fluorogenic Substrates

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Enzyme/substrate pairs are crucial reporters for monitoring biological events.
• Existing reporter systems necessitate orthogonal alternatives for broader applications.

Purpose of the Study:

• To design and synthesize novel fluorogenic substrates for azoreductase (AzoR).
• To establish a new reporter system for detecting azoreductase activity in live cells.

Main Methods:

• Synthesis of a library of azo-rhodamine derivatives as potential fluorogenic substrates.
• Evaluation of AzoR-mediated reduction and subsequent nonenzymatic cleavage.
• Assessment of substrate performance in detecting azoreductase-expressing cells.

Main Results:

• Developed nonfluorescent azo-rhodamine derivatives that become highly fluorescent upon AzoR-mediated reduction.
• Identified a specific derivative that, upon reduction, yields 2-methyl-rhodamine green (2-Me RG), a retained fluorophore.
• Demonstrated the AzoR/compound 9 reporter system's ability to detect azoreductase-expressing live cells at the single-cell level.

Conclusions:

• The novel AzoR/compound 9 reporter system offers a sensitive and specific method for detecting azoreductase activity.
• This system provides an orthogonal reporter tool for biological research.
• The developed fluorogenic substrates show promise for live-cell imaging and diagnostics.