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PDBsum entry 2avs
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References listed in PDB file
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Key reference
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Title
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Kinetic, Stability, And structural changes in high-Resolution crystal structures of HIV-1 protease with drug-Resistant mutations l24i, I50V, And g73s.
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Authors
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F.Liu,
P.I.Boross,
Y.F.Wang,
J.Tozser,
J.M.Louis,
R.W.Harrison,
I.T.Weber.
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Ref.
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J Mol Biol, 2005,
354,
789-800.
[DOI no: ]
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PubMed id
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Abstract
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The crystal structures, dimer stabilities, and kinetics have been analyzed for
wild-type human immunodeficiency virus type 1 (HIV-1) protease (PR) and
resistant mutants PR(L24I), PR(I50V), and PR(G73S) to gain insight into the
molecular basis of drug resistance. The mutations lie in different structural
regions. Mutation I50V alters a residue in the flexible flap that interacts with
the inhibitor, L24I alters a residue adjacent to the catalytic Asp25, and G73S
lies at the protein surface far from the inhibitor-binding site. PR(L24I) and
PR(I50V), showed a 4% and 18% lower k(cat)/K(m), respectively, relative to PR.
The relative k(cat)/K(m) of PR(G73S) varied from 14% to 400% when assayed using
different substrates. Inhibition constants (K(i)) of the antiviral drug
indinavir for the reaction catalyzed by the mutant enzymes were about threefold
and 50-fold higher for PR(L24I) and PR(I50V), respectively, relative to PR and
PR(G73S). The dimer dissociation constant (K(d)) was estimated to be
approximately 20 nM for both PR(L24I) and PR(I50V), and below 5 nM for PR(G73S)
and PR. Crystal structures of the mutants PR(L24I), PR(I50V) and PR(G73S) were
determined in complexes with indinavir, or the p2/NC substrate analog at
resolutions of 1.10-1.50 Angstrom. Each mutant revealed distinct structural
changes relative to PR. The mutated residues in PR(L24I) and PR(I50V) had
reduced intersubunit contacts, consistent with the increased K(d) for dimer
dissociation. Relative to PR, PR(I50V) had fewer interactions of Val50 with
inhibitors, in agreement with the dramatically increased K(i). The distal
mutation G73S introduced new hydrogen bond interactions that can transmit
changes to the substrate-binding site and alter catalytic activity. Therefore,
the structural alterations observed for drug-resistant mutations were in
agreement with kinetic and stability changes.
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Figure 1.
Figure 1. PR dimer structure (green ribbons) with indinavir
(red bonds). The sites of mutation are indicated by black
spheres for Leu24, Ile50 and Gly73. Only one subunit is labeled.
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Figure 6.
Figure 6. Protease-inhibitor interactions. Only the
residues involved in hydrogen bond interactions are shown. Water
molecules are represented as spheres. Hydrogen bonds are
indicated by broken lines. (a) PR[L24I] hydrogen bond
interactions with indinavir. Water molecules are labeled A-D.
(b) Interactions of Arg8' with the pyridyl group of indinavir in
PR[I50V]-IDV. The omit map is contoured at 3.5s. (c) PR[L24I]
interactions with p2/NC. Water molecules are labeled 1-8. Arg8
and Arg8' are omitted for clarity. (d) Selected interactions of
the side-chains of Ile/Leu50 and 50' with indinavir in the
PR[I50V] and PR indinavir complexes. PR-IDV is in green and
PR[I50V]-IDV is red. Only the central portion of indinavir is
shown with van der Waals contacts indicated by dotted lines with
distances in Å.
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The above figures are
reprinted
from an Open Access publication published by Elsevier:
J Mol Biol
(2005,
354,
789-800)
copyright 2005.
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