Elucidating molecular interactions of L-nucleotides with HIV-1 reverse transcriptase and mechanism of M184V-caused drug resistance

Commun Biol. 2019 Dec 13;2:469. doi: 10.1038/s42003-019-0706-x. eCollection 2019.


Emtricitabine (FTC) and lamivudine (3TC), containing an oxathiolane ring with unnatural (-)-stereochemistry, are widely used nucleoside reverse transcriptase inhibitors (NRTIs) in anti-HIV therapy. Treatment with FTC or 3TC primarily selects for the HIV-1 RT M184V/I resistance mutations. Here we provide a comprehensive kinetic and structural basis for inhibiting HIV-1 RT by (-)-FTC-TP and (-)-3TC-TP and drug resistance by M184V. (-)-FTC-TP and (-)-3TC-TP have higher binding affinities (1/K d) for wild-type RT but slower incorporation rates than dCTP. HIV-1 RT ternary crystal structures with (-)-FTC-TP and (-)-3TC-TP corroborate kinetic results demonstrating that their oxathiolane sulfur orients toward the DNA primer 3'-terminus and their triphosphate exists in two different binding conformations. M184V RT displays greater (>200-fold) K d for the L-nucleotides and moderately higher (>9-fold) K d for the D-isomers compared to dCTP. The M184V RT structure illustrates how the mutation repositions the oxathiolane of (-)-FTC-TP and shifts its triphosphate into a non-productive conformation.

Keywords: Enzyme mechanisms; HIV infections; Pharmaceutics; X-ray crystallography.

Publication types

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

MeSH terms

  • Alleles
  • Amino Acid Substitution
  • Databases, Genetic
  • Drug Resistance, Viral*
  • HIV Infections / drug therapy
  • HIV Infections / virology
  • HIV Reverse Transcriptase / antagonists & inhibitors
  • HIV Reverse Transcriptase / chemistry*
  • HIV Reverse Transcriptase / genetics*
  • HIV-1 / drug effects*
  • HIV-1 / enzymology
  • HIV-1 / genetics*
  • Humans
  • Microbial Sensitivity Tests
  • Mutation
  • Nucleotides / chemistry*
  • Nucleotides / pharmacology
  • Reverse Transcriptase Inhibitors / chemistry*
  • Reverse Transcriptase Inhibitors / pharmacology


  • Nucleotides
  • Reverse Transcriptase Inhibitors
  • reverse transcriptase, Human immunodeficiency virus 1
  • HIV Reverse Transcriptase