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M9640844.TXT
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1996-03-04
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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).