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Updated: Dec 28, 2025

A High-Throughput Enzyme-Coupled Activity Assay to Probe Small Molecule Interaction with the dNTPase SAMHD1
Published on: April 16, 2021
Viperin, through its radical-SAM activity, depletes cellular nucleotide pools and interferes with mitochondrial
Kourosh H Ebrahimi1, Duncan Howie2, Jack S Rowbotham1
1Department Chemistry, University of Oxford, UK.
Abstract:
Viperin (RSAD2) is an antiviral radical S-adenosylmethionine (SAM) enzyme highly expressed in different cell types upon viral infection. Recently, it has been reported that the radical-SAM activity of viperin transforms cytidine triphosphate (CTP) to its analogue 3'-deoxy-3',4'-didehydro-CTP (ddhCTP). Based on biochemical studies and cell biological experiments, it was concluded that ddhCTP and its nucleoside form ddhC do not affect the cellular concentration of nucleotide triphosphates and that ddhCTP acts as replication chain terminator. However, our re-evaluation of the reported data and new results indicate that ddhCTP is not an effective viral chain terminator but depletes cellular nucleotide pools and interferes with mitochondrial activity to inhibit viral replication. Our analysis is consistent with a unifying view of the antiviral and radical-SAM activities of viperin.
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