Figure 1.

Overview of viperin's role in TLR7/9 signaling and antiviral ribonucleotide synthesis. a, viperin facilitates the activation of IRAK1 for phosphorylation of IRF7 in the TLR7/9 signaling pathway. b, structure of viperin (PDB code 5VSL); the canonical radical SAM domain is shown in blue and the viperin-specific C-terminal domain is shown green; the [4Fe-4S] cluster is shown as spheres and the structure of SAH as sticks. c, details of the active site showing the [4Fe-4S] cluster (spheres), the ligating cysteine residues of the CXXXCXXC motif and SAH bound (sticks). d, SAM-dependent dehydration of CTP to ddhCTP catalyzed by viperin.