A Reader-Based Assay for mA Writers and Erasers.

We have developed a homogeneous time-resolved fluorescence (HTRF)-based enzyme assay to measure the catalytic activity of N-methyladenosine (mA) methyltransferases and demethylases. The assay detects mA modifications using the natural mA-binding proteins (mA readers). The reaction product or substrate mA-containing RNA and the mA reader protein are fluorescently labeled such that their proximity during binding initiates Förster resonance energy transfer (FRET). We show that our HTRF assay can be used for high-throughput screening, which will facilitate the discovery of small-molecule modulators of mA (de)methylases.