Target Class Profiling of Small-Molecule Methyltransferases

Target class profiling (TCP) is a chemical biology approach to investigate understudied biological target classes. TCP is achieved by developing a generalizable assay platform and screening curated compound libraries to interrogate the chemical biological space of members of an enzyme family. In this work, we took a TCP approach to investigate inhibitory activity across a set of small-molecule methyltransferases (SMMTases), a subclass of methyltransferase enzymes, with the goal of creating a launchpad to explore this largely understudied target class. Using the representative enzymes nicotinamide N-methyltransferase (NNMT), phenylethanolamine N-methyltransferase (PNMT), histamine N-methyltransferase (HNMT), glycine N-methyltransferase (GNMT), catechol O-methyltransferase (COMT), and guanidinoacetate N-methyltransferase (GAMT), we optimized high-throughput screening (HTS)-amenable assays to screen 27,574 unique small molecules against all targets. From this data set, we identified a novel inhibitor which selectively inhibits the SMMTase HNMT and demonstrated how this platform approach can be leveraged for a targeted drug discovery campaign using the example of HNMT.

Automated summary

Target class profiling (TCP) is a chemistry biology approach used to investigate understudied biological targets. By developing a generalizable assay platform and screening curated compound libraries, TCP explores the chemical biological space of enzyme families. In this study, TCP was used to investigate inhibitory activity in a set of small-molecule methyltransferases (SMMTases) in order to explore this relatively unexplored target class. High-throughput screening (HTS)-amenable assays were optimized to screen a large number of small molecules against representative SMMTases, resulting in the identification of a novel inhibitor for the SMMTase HNMT.