High-throughput real-time assay based on molecular beacons for HIV-1 integrase 3'-processing reaction

Area of Science:

• Biochemistry
• Molecular Biology
• Virology

Background:

• Human immunodeficiency virus (HIV) integrase (IN) is a critical enzyme for viral replication.
• The 3 -processing reaction is a key step in the IN catalytic cycle.
• Developing efficient assays for monitoring IN activity is crucial for antiviral drug discovery.

Purpose of the Study:

• To develop a high-throughput, real-time assay for monitoring the HIV-1 integrase 3 -processing reaction.
• To apply this novel assay for screening potential HIV integrase inhibitors.

Main Methods:

• A molecular beacon-based assay utilizing a fluorescently labeled oligonucleotide substrate was designed.
• The substrate forms a stem-loop structure with a quencher, releasing fluorescence upon cleavage by HIV-1 IN.
• Optimization of substrate, enzyme, and metal ion concentrations was performed.
• The assay's performance was validated using known integrase inhibitors.

Main Results:

• The assay demonstrated a linear correlation between fluorescence intensity and the rate of the 3 -processing reaction.
• Optimal reaction conditions were determined (50 mg/L IN, 400 nmol/L substrate, 10 mmol/L Mn2+).
• A significant fluorescence increase (>18-fold) was observed under optimal conditions.
• Inhibitor screening yielded IC50 values comparable to traditional radiolabeled assays.

Conclusions:

• The developed molecular beacon assay is a fast, reliable, and sensitive method for monitoring HIV integrase 3 -processing.
• This assay is suitable for high-throughput screening of antiviral compounds targeting HIV integrase.