• NUDT2 initiates viral RNA degradation by removal of 5'-phosphates.

      Laudenbach, Beatrice T; Krey, Karsten; Emslander, Quirin; Andersen, Line Lykke; Reim, Alexander; Scaturro, Pietro; Mundigl, Sarah; Dächert, Christopher; Manske, Katrin; Moser, Markus; et al. (Springer Nature, 2021-11-25)
      While viral replication processes are largely understood, comparably little is known on cellular mechanisms degrading viral RNA. Some viral RNAs bear a 5'-triphosphate (PPP-) group that impairs degradation by the canonical 5'-3' degradation pathway. Here we show that the Nudix hydrolase 2 (NUDT2) trims viral PPP-RNA into monophosphorylated (P)-RNA, which serves as a substrate for the 5'-3' exonuclease XRN1. NUDT2 removes 5'-phosphates from PPP-RNA in an RNA sequence- and overhang-independent manner and its ablation in cells increases growth of PPP-RNA viruses, suggesting an involvement in antiviral immunity. NUDT2 is highly homologous to bacterial RNA pyrophosphatase H (RppH), a protein involved in the metabolism of bacterial mRNA, which is 5'-tri- or diphosphorylated. Our results show a conserved function between bacterial RppH and mammalian NUDT2, indicating that the function may have adapted from a protein responsible for RNA turnover in bacteria into a protein involved in the immune defense in mammals.