Probing the molecular mechanism of action of the HIV-1 reverse transcriptase inhibitor 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) using pre-steady-state kinetics

Antiviral Res. 2014 Jun;106:1-4. doi: 10.1016/j.antiviral.2014.03.001. Epub 2014 Mar 12.


The novel antiretroviral 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA) is a potent nucleoside HIV-1 reverse transcriptase (RT) inhibitor (NRTI). Unlike other FDA-approved NRTIs, EFdA contains a 3'-hydroxyl. Pre-steady-state kinetics showed RT preferred incorporating EFdA-TP over native dATP. Moreover, RT slowly inserted nucleotides past an EFdA-terminated primer, resulting in delayed chain termination with unaffected fidelity. This is distinct from KP1212, another 3'-hydroxyl-containing RT inhibitor considered to promote viral lethal mutagenesis. New mechanistic features of RT inhibition by EFdA are revealed.

Keywords: EFdA; Enzyme kinetics; HIV; Polymerase; Reverse transcriptase.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anti-HIV Agents / pharmacology*
  • Deoxyadenosines / pharmacology*
  • HIV Reverse Transcriptase / antagonists & inhibitors*
  • HIV-1 / drug effects
  • HIV-1 / enzymology*
  • Kinetics
  • Reverse Transcriptase Inhibitors / pharmacology*


  • Anti-HIV Agents
  • Deoxyadenosines
  • Reverse Transcriptase Inhibitors
  • reverse transcriptase, Human immunodeficiency virus 1
  • HIV Reverse Transcriptase
  • 4'-ethynyl-2-fluoro-2'-deoxyadenosine