Structural basis for activation of the therapeutic L-nucleoside analogs 3TC and troxacitabine by human deoxycytidine kinase

Elisabetta Sabini, Saugata Hazra, Manfred Konrad, Stephen K. Burley, Arnon Lavie

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


L-nucleoside analogs represent an important class of small molecules for treating both viral infections and cancers. These pro-drugs achieve pharmacological activity only after enzyme-catalyzed conversion to their tri-phosphorylated forms. Herein, we report the crystal structures of human deoxycytidine kinase (dCK) in complex with the L-nucleosides (-)-β-2′,3′-dideoxy-3′-thiacytidine (3TC) - an approved anti-human immunodeficiency virus (HIV) agent - and troxacitabine (TRO) - an experimental anti-neoplastic agent. The first step in activating these agents is catalyzed by dCK. Our studies reveal how dCK, which normally catalyzes phosphorylation of the natural d-nucleosides, can efficiently phosphorylate substrates with non-physiologic chirality. The capability of dCK to phosphorylate both D- and L-nucleosides and nucleoside analogs derives from structural properties of both the enzyme and the substrates themselves. First, the nucleoside-binding site tolerates substrates with different chiral configurations by maintaining virtually all of the protein-ligand interactions responsible for productive substrate positioning. Second, the pseudo-symmetry of nucleosides and nucleoside analogs in combination with their conformational flexibility allows the L- and D-enantiomeric forms to adopt similar shapes when bound to the enzyme. This is the first analysis of the structural basis for activation of L-nucleoside analogs, providing further impetus for discovery and clinical development of new agents in this molecular class.

Original languageEnglish (US)
Pages (from-to)186-192
Number of pages7
JournalNucleic acids research
Issue number1
StatePublished - Jan 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics


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