Label-free detection of dam methyltransferase activity and inhibition via malachite green aptamer generated by T7 RNA polymerase†

DNA methyltransferase (DNA MTase) catalyzes DNA methylation, which plays a crucial role in various biological processes such as chromatin assembly, aging, and tumorigenesis. For this reason, developing handy DNA MTase assays and screening its inhibitors have potential value in clinical applications. Here, we have established a label-free strategy for Dam MTase, using the T7 RNA transcription system for signal amplification and its transcription product malachite green aptamer (MGA) for signal transduction. This strategy reached a detection limit of 9.95 × 10⁻⁵ U mL⁻¹ and successfully achieved detection in a complex biological matrix. Simultaneously, this method has realized the screening of methyltransferase inhibitors, laying a solid foundation for its clinical application.