ATPase activity profiling of three human DExD/H-box RNA helicases

Human DExD/H-box RNA helicases are ubiquitous molecular motors that unwind and rearrange RNA secondary structures in an ATP-dependent manner. These enzymes play essential roles in nearly all aspects of RNA metabolism. While their biological functions are well-characterized, the kinetic mechanisms remain relatively understudied in vitro. In this study, we describe the development and optimization of a bioluminescence-based assay to characterize the ATPase activity of three human RNA helicases: MDA5, LGP2, and DDX1. The assays were conducted using annealed 24-mer ds-RNA (blunt-ended double-stranded RNA) or double-stranded RNA with a 25-nt 3ʹ overhang (partial ds-RNA). These findings establish a robust and high-throughput in vitro assay suitable for a 384-well format, enabling the discovery and characterization of inhibitors targeting MDA5, LGP2, and DDX1. This work provides a valuable resource for advancing our understanding of these helicases and their therapeutic potential in Alzheimer's disease.