A nonradioactive DNA methyltransferase assay adaptable to high-throughput screening

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• DNA methyltransferases (DNMTs) play critical roles in gene regulation and are targets for cancer therapy.
• Existing assays for DNMT activity often rely on radioactivity or lack versatility.
• A robust, nonradioactive method is needed for efficient screening of DNMT inhibitors.

Purpose of the Study:

• To develop and validate a novel, nonradioactive assay for quantifying DNA methyltransferase activity.
• To create a universal substrate applicable to various DNMTs, including those lacking specific restriction enzyme sites.
• To establish a high-throughput screening (HTS) compatible method for identifying DNMT inhibitors.

Main Methods:

• Immobilization of a universal DNA substrate onto microplate wells.
• Sequential treatment of the immobilized DNA with target DNA methyltransferase and a corresponding endonuclease.
• Quantification of enzyme activity by measuring the retention of an end-labeled affinity probe, inversely proportional to endonuclease cleavage.

Main Results:

• The assay demonstrates a clear inverse correlation between DNA methyltransferase activity and endonuclease cleavage.
• The method successfully quantifies activity for multiple DNA methyltransferases using a single substrate.
• The assay is suitable for screening compound libraries for potential DNMT inhibitors.

Conclusions:

• A versatile, nonradioactive assay for DNA methyltransferases has been successfully developed.
• This methodology facilitates the discovery of novel inhibitors for therapeutic applications.
• The assay's design supports high-throughput screening for drug development targeting DNA methylation pathways.