Small Molecule Inhibition of SAMHD1 dNTPase by Tetramer Destabilization

SAMHD1 is a GTP-activated nonspecific dNTP triphosphohydrolase that depletes dNTP pools in resting CD4+ T cells and macrophages and effectively restricts infection by HIV-1. We have designed a nonsubstrate dUTP analogue with a methylene bridge connecting the α phosphate and 5′ carbon that potently inhibits SAMHD1. Although pppCH2dU shows apparent competitive inhibition, it acts by a surprising allosteric mechanism that destabilizes active enzyme tetramer.