       Document 0844
 DOCN  M9640844
 TI    HIV-1 reverse transcriptase resistance to nonnucleoside inhibitors.
 DT    9604
 AU    Spence RA; Anderson KS; Johnson KA; Department of Biochemistry and
       Molecular Biology, Pennsylvania; State University, University Park
       16802, USA.
 SO    Biochemistry. 1996 Jan 23;35(3):1054-63. Unique Identifier : AIDSLINE
       MED/96146442
 AB    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.
 DE    Antiviral Agents/*METABOLISM  Binding Sites  Deoxyadenine
       Nucleotides/METABOLISM  Drug Resistance  DNA/METABOLISM
       Pyridines/*METABOLISM  Reverse Transcriptase Inhibitors/*METABOLISM
       RNA-Directed DNA Polymerase/*METABOLISM  Support, U.S. Gov't, P.H.S.
       JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

