Substrate mimicry: HIV-1 reverse transcriptase recognizes 6-modified-3'-azido-2',3'-dideoxyguanosine-5'-triphosphates as adenosine analogs

Nucleic Acids Res. 2012 Jan;40(1):381-90. doi: 10.1093/nar/gkr756. Epub 2011 Sep 13.


β-D-3'-Azido-2',3'-dideoxyguanosine (3'-azido-ddG) is a potent inhibitor of HIV-1 replication with a superior resistance profile to zidovudine. Recently, we identified five novel 6-modified-3'-azido-ddG analogs that exhibit similar or superior anti-HIV-1 activity compared to 3'-azido-ddG in primary cells. To gain insight into their structure-activity-resistance relationships, we synthesized their triphosphate (TP) forms and assessed their ability to inhibit HIV-1 reverse transcriptase (RT). Steady-state and pre-steady-state kinetic experiments show that the 6-modified-3'-azido-ddGTP analogs act as adenosine rather than guanosine mimetics in DNA synthesis reactions. The order of potency of the TP analogs against wild-type RT was: 3'-azido-2,6-diaminopurine >3'-azido-6-chloropurine; 3'-azido-6-N-allylaminopurine > 2-amino-6-N,N-dimethylaminopurine; 2-amino-6-methoxypurine. Molecular modeling studies reveal unique hydrogen-bonding interactions between the nucleotide analogs and the template thymine base in the active site of RT. Surprisingly, the structure-activity relationship of the analogs differed in HIV-1 RT ATP-mediated excision assays of their monophosphate forms, suggesting that it may be possible to rationally design a modified base analog that is efficiently incorporated by RT but serves as a poor substrate for ATP-mediated excision reactions. Overall, these studies identify a promising strategy to design novel nucleoside analogs that exert profound antiviral activity against both WT and drug-resistant HIV-1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine / analogs & derivatives
  • Adenosine Triphosphate / chemistry
  • Anti-HIV Agents / chemistry*
  • Anti-HIV Agents / metabolism
  • Catalytic Domain
  • Dideoxynucleosides / chemistry*
  • Dideoxynucleotides / chemistry*
  • Dideoxynucleotides / metabolism
  • HIV Reverse Transcriptase / chemistry*
  • HIV Reverse Transcriptase / genetics
  • HIV Reverse Transcriptase / metabolism
  • Models, Molecular
  • Molecular Mimicry
  • Mutation
  • Reverse Transcriptase Inhibitors / chemistry*
  • Reverse Transcriptase Inhibitors / metabolism


  • Anti-HIV Agents
  • Dideoxynucleosides
  • Dideoxynucleotides
  • Reverse Transcriptase Inhibitors
  • 3'-azido-2',3'-dideoxyguanosine
  • Adenosine Triphosphate
  • reverse transcriptase, Human immunodeficiency virus 1
  • HIV Reverse Transcriptase
  • Adenosine