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PDBsum entry 1k2b
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Hydrolase/hydrolase inhibitor
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PDB id
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1k2b
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Combining mutations in HIV-1 protease to understand mechanisms of resistance.
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Authors
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B.Mahalingam,
P.Boross,
Y.F.Wang,
J.M.Louis,
C.C.Fischer,
J.Tozser,
R.W.Harrison,
I.T.Weber.
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Ref.
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Proteins, 2002,
48,
107-116.
[DOI no: ]
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PubMed id
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Abstract
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HIV-1 develops resistance to protease inhibitors predominantly by selecting
mutations in the protease gene. Studies of resistant mutants of HIV-1 protease
with single amino acid substitutions have shown a range of independent effects
on specificity, inhibition, and stability. Four double mutants, K45I/L90M,
K45I/V82S, D30N/V82S, and N88D/L90M were selected for analysis on the basis of
observations of increased or decreased stability or enzymatic activity for the
respective single mutants. The double mutants were assayed for catalysis,
inhibition, and stability. Crystal structures were analyzed for the double
mutants at resolutions of 2.2-1.2 A to determine the associated molecular
changes. Sequence-dependent changes in protease-inhibitor interactions were
observed in the crystal structures. Mutations D30N, K45I, and V82S showed
altered interactions with inhibitor residues at P2/P2', P3/P3'/P4/P4', and
P1/P1', respectively. One of the conformations of Met90 in K45I/L90M has an
unfavorably close contact with the carbonyl oxygen of Asp25, as observed
previously in the L90M single mutant. The observed catalytic efficiency and
inhibition for the double mutants depended on the specific substrate or
inhibitor. In particular, large variation in cleavage of p6(pol)-PR substrate
was observed, which is likely to result in defects in the maturation of the
protease from the Gag-Pol precursor and hence viral replication. Three of the
double mutants showed values for stability that were intermediate between the
values observed for the respective single mutants. D30N/V82S mutant showed lower
stability than either of the two individual mutations, which is possibly due to
concerted changes in the central P2-P2' and S2-S2' sites. The complex effects of
combining mutations are discussed.
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Figure 1.
Figure 1. Location of the mutations in HIV-1 protease dimer.
Residues 1-99 correspond to one monomer of the homodimer. The
sites of mutations are indicated by ball-and-stick
representations. The residue numbers of the mutations are
labeled in one subunit.
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Figure 3.
Figure 3. Electron density map contoured at 1.8  level
for the catalytic aspartates in the K45I/V82S crystal structure
refined at 1.2 Å.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2002,
48,
107-116)
copyright 2002.
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