Vol. 63, Issue 3, 538-546, March 2003

Structural Analysis of the Activation of Ribavirin Analogs by NDP Kinase: Comparison with Other Ribavirin Targets

Sarah Gallois-Montbrun, Yuxing Chen, Hélène Dutartre, Magali Sophys, Solange Morera, Catherine Guerreiro, Benoit Schneider,¹ Laurence Mulard, Joël Janin, Michel Veron, Dominique Deville-Bonne, and Bruno Canard

Unité de Régulation Enzymatique des Activités Cellulaires, Centre National de la Recherche Scientifique (CNRS) Formation de Recherche en Evolution 2364, Institut Pasteur, Paris, France (S.G.-M., B.S., M.V., D.D.-B.); Laboratoire d'Enzymologie et de Biochimie Structurales, CNRS Unité Propre de Recherche 9063, Gif-sur-Yvette, France (Y.C., S.M., J.J.); Laboratoire d'Architecture et Fonction des Macromolecules Biologiques, CNRS Unité Mixte de Recherche 6098, Ecole Supérieure d'Ingénieurs de Luminy, case 925, Marseille, France (H.D., M.S., B.C.); and Unité de Chimie Organique, CNRS Unité de Recherche Associée 2128, Institut Pasteur, Paris, France (C.G., L.M.)

Ribavirin used in therapies against hepatitis C virus (HCV) is potentially efficient against other viruses but presents a high cytotoxicity. Several ribavirin triphosphate analogs modified on the ribose moiety were synthesized and tested in vitro on the RNA polymerases of HCV, phage T7, and HIV-1 reverse transcriptase. Modified nucleotides with 2'-deoxy, 3'-deoxy, 2',3'-dideoxy, 2',3'-dideoxy-2',3'-dehydro, and 2',3'-epoxy-ribose inhibited the HCV enzyme but not the other two polymerases. They were also analyzed as substrates for nucleoside diphosphate (NDP) kinase, the enzyme responsible for the last step of the cellular activation of antiviral nucleoside analogs. An X-ray structure of NDP kinase complexed with ribavirin triphosphate was determined. It demonstrates that the analog binds as a normal substrate despite the modified base and confirms the crucial role of the 3'-hydroxyl group in the phosphorylation reaction. The 3'-hydroxyl is required for inhibition of the initiation step of RNA synthesis by HCV polymerase, and both sugar hydroxyls must be present to inhibit elongation. The 2'deoxyribavirin is the only derivative efficient in vitro against HCV polymerase and properly activated by NDP kinase.