A Proposed Mechanism for the Radical SAM Enzyme Viperin

Viperin is a radical SAM enzyme that is expressed during the interferon response. While viperin has been shown to inhibit a broad range of viruses, its molecular mechanism has remained elusive. Our biochemical assays suggest that viperin catalyzes a radical addition on isopentenyl pyrophosphate (IPP) to create a new compound called adenylated isopentyl pyrophosphate (AIPP). Since IPP is a key intermediate of the mevalonate pathway which is important for biological functions such as cholesterol biosynthesis and protein prenylation, we suspect that viperin exhibits its antiviral activity through interference of this pathway. Alternatively, AIPP might have inhibitory effects itself, but further in vivo studies have to be done.Ope