The activation cascade of the broad-spectrum antiviral bemnifosbuvir characterized at atomic resolution

Abstract

AU Bemnifosbuvir: Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly (AT-527) and AT-752 are guanosine analogues : currently in clinical trials against several RNA viruses. Here, we show that these drugs require a minimal set of 5 cellular enzymes for activation to their common 50-triphosphate AT-9010, with an obligate order of reactions. AT-9010 selectively inhibits essential viral enzymes, accounting for antiviral potency. Functional and structural data at atomic resolution decipher N6-purine deamination compatible with its metabolic activation. Crystal structures of human histidine triad nucleotide binding protein 1, adenosine deaminase-like protein 1, guanylate kinase 1, and nucleoside diphosphate kinase at 2.09, 2.44, 1.76, and 1.9 Å resolution, respectively, with cognate precursors of AT-9010 illuminate the activation pathway from the orally available bemnifosbuvir to AT-9010, pointing to key drug–protein contacts along the activation pathway. Our work provides a framework to integrate the design of antiviral nucleotide analogues, confronting requirements and constraints associated with activation enzymes along the 50-triphosphate assembly line.