HIV-1 reverse transcriptase resistance to nonnucleoside inhibitors

Biochemistry. 1996 Jan 23;35(3):1054-63. doi: 10.1021/bi952058+.


The parameters governing the polymerization mechanism of reverse transcriptase containing the tyrosine to cysteine mutation at position 181 (Y181C) were determined using pre-steady-state techniques. The pathway for single nucleotide incorporation catalyzed by Y181C is similar to that determined for wild-type RT where a rate-limiting conformational change precedes fast chemistry and is followed by slow steady-state release of the primer/template. The Y181C mutant enzyme binds a 25/45-mer duplex DNA tightly with a Kd of 11 nM. However, the Y181C mutation weakens the nucleotide affinity 2-3-fold relative to the wild-type complex. We also determined the parameters governing the mechanism of nonnucleoside inhibitor resistance with Y181C. The Kd value of Nevirapine with the mutant E.DNA complex increased approximately 500-fold. The decreased affinity of Nevirapine for the mutant enzyme is a consequence of a faster inhibitor dissociation rate from the enzyme complex of Y181C relative to that of the wild-type. The E.DNA complex of Y181C may be saturated with Nevirapine, and the I.E.DNA complex is capable of a maximum incorporation rate of 0.1 s-1 (a 10-fold faster rate than that of the wild-type I.E.DNA complex). The overall two-step binding of nucleotide to Y181C in the presence of Nevirapine remains unaffected.

Publication types

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

MeSH terms

  • Antiviral Agents / metabolism*
  • Binding Sites
  • DNA / metabolism
  • Deoxyadenine Nucleotides / metabolism
  • Drug Resistance
  • HIV Reverse Transcriptase
  • Nevirapine
  • Pyridines / metabolism*
  • RNA-Directed DNA Polymerase / metabolism*
  • Reverse Transcriptase Inhibitors / metabolism*


  • Antiviral Agents
  • Deoxyadenine Nucleotides
  • Pyridines
  • Reverse Transcriptase Inhibitors
  • DNA
  • Nevirapine
  • HIV Reverse Transcriptase
  • RNA-Directed DNA Polymerase
  • 2'-deoxyadenosine triphosphate