β-Nicotinamide mononucleotide: a novel broad-spectrum CRISPR inhibitor

CRISPR–Cas systems have revolutionized genome editing with their precision and versatility, enabling transformative applications in various fields, especially in the treatment of genetic diseases. However, the clinical translation of this technology is hindered by challenges such as off-target effects and uncontrolled nuclease activity. At the same time, it has the possibility of causing biosecurity risks, underscoring the urgent need for reliable regulatory tools. Existing CRISPR inhibitors, primarily anti-CRISPR protein or exogenously synthesized small molecules, are limited by their specificity or bioavailability and long research period, unable to address the diverse CRISPR nucleases used in research and therapy. Based on the phenomena obtained from various in vitro and cell experiments, combining molecular dynamics simulation and bio - layer interferometry (BLI) analysis, here we report a naturally occurring small-molecule β-nicotinamide mononucleotide (NMN), the first known endogenous metabolite with broad-spectrum inhibitory activity against multiple CRISPR-associated proteins (Cas9, Cas12, and Cas13) through various mechanisms. Our findings establish NMN as a dual-purpose tool, which reduces cell damage caused by gene editing and mitigates risks of unintended genetic modifications in research and clinical settings. This discovery further shortens the distance between basic medicine and translational medicine, providing a new approach for developing endogenous regulatory molecules in genome engineering.