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PDBsum entry 1ff0
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Hydrolase/hydrolase inhibitor
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PDB id
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1ff0
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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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Structural implications of drug-Resistant mutants of HIV-1 protease: high-Resolution crystal structures of the mutant protease/substrate analogue complexes.
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Authors
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B.Mahalingam,
J.M.Louis,
J.Hung,
R.W.Harrison,
I.T.Weber.
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Ref.
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Proteins, 2001,
43,
455-464.
[DOI no: ]
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PubMed id
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Abstract
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Emergence of drug-resistant mutants of HIV-1 protease is an ongoing problem in
the fight against AIDS. The mechanisms governing resistance are both complex and
varied. We have determined crystal structures of HIV-1 protease mutants, D30N,
K45I, N88D, and L90M complexed with peptide inhibitor analogues of CA-p2 and
p2-NC cleavage sites in the Gag-pol precursor in order to study the structural
mechanisms underlying resistance. The structures were determined at 1.55-1.9-A
resolution and compared with the wild-type structure. The conformational
disorder seen for most of the hydrophobic side-chains around the inhibitor
binding site indicates flexibility of binding. Eight water molecules are
conserved in all 9 structures; their location suggests that they are important
for catalysis as well as structural stability. Structural differences among the
mutants were analyzed in relation to the observed changes in protease activity
and stability. Mutant L90M shows steric contacts with the catalytic Asp25 that
could destabilize the catalytic loop at the dimer interface, leading to its
observed decreased dimer stability and activity. Mutant K45I reduces the
mobility of the flap and the inhibitor and contributes to an enhancement in
structural stability and activity. The side-chain variations at residue 30
relative to wild-type are the largest in D30N and the changes are consistent
with the altered activity observed with peptide substrates. Polar interactions
in D30N are maintained, in agreement with the observed urea sensitivity. The
side-chains of D30N and N88D are linked through a water molecule suggesting
correlated changes at the two sites, as seen with clinical inhibitors.
Structural changes seen in N88D are small; however, water molecules that mediate
interactions between Asn88 and Thr74/Thr31/Asp30 in other complexes are missing
in N88D.
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Figure 2.
Figure 2. Hydrophobic residues around the inhibitor with poorly
defined electron density for the side-chains are shown in black.
The catalytic aspartates are shown in gray.
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Figure 3.
Figure 3. Superposition of inhibitors. The CA-p2 inhibitors are
in black and the p2-NC inhibitors are in gray. All mutants were
superposed onto the wild-type/p2-NC complex.
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2001,
43,
455-464)
copyright 2001.
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