NUDT18 catalyzes the hydrolysis of active metabolites of the antivirals Remdesivir, Ribavirin and Molnupiravir

Abstract

Remdesivir (GS-5734) has gained considerable interest due to its activity against replication of SARS-CoV2. Remdesivir is a broad-spectrum antiviral prodrug that is hydrolyzed intracellularly and phosphorylated by cellular kinases to its active triphosphate form (Remdesivir-TP). Here we tested Remdesivir-TP as a substrate for a panel of human hydrolases and found that NUDIX hydrolase 18 (NUDT18) catalyzes the hydrolysis of Remdesivir-TP. NUDT18 is expressed in respiratory epithelial cells suggesting that NUDT18 may limit the antiviral efficacy of Remdesivir by decreasing the intracellular concentration of its active metabolite at its intended site of action. The kcat of NUDT18 for Remdesivir-TP was determined to 2.6 s-1 and the Km value was 156 μM, suggesting that NUDT18 catalyzed hydrolysis occurs in cells. In addition, we found that the triphosphate of the antiviral Ribavirin, with broad-spectrum activity against several RNA and DNA viruses, was hydrolyzed by NUDT18, albeit with a lower efficiency compared to Remdesivir-TP. NUDT18 activity was also tested with the triphosphates of the antivirals Sofosbuvir and Aciclovir for which low activity, in comparison to activities with Remdesivir-TP and Ribavirin-TP, was detected. These results suggest that NUDT18 can act as a cellular sanitizer and may influence the antiviral efficacy of Remdesivir and Ribavirin.