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PDBsum entry 2bc3
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Biotin binding protein
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PDB id
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2bc3
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References listed in PDB file
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Key reference
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Title
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Crystallographic analysis of a full-Length streptavidin with its c-Terminal polypeptide bound in the biotin binding site.
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Authors
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I.Le trong,
N.Humbert,
T.R.Ward,
R.E.Stenkamp.
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Ref.
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J Mol Biol, 2006,
356,
738-745.
[DOI no: ]
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PubMed id
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Abstract
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The structure of a full-length streptavidin has been determined at 1.7A
resolution and shows that the 20 residue extension at the C terminus forms a
well-ordered polypeptide loop on the surface of the tetramer. Residues 150-153
of the extension are bound to the ligand-binding site, possibly competing with
exogenous ligands. The binding mode of these residues is compared with that of
biotin and peptidic ligands. The observed structure helps to rationalize the
observations that full-length mature streptavidin binds biotinylated
macromolecules with reduced affinity.
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Figure 4.
Figure 4. Stereo view of a subunit of wild-type
core-streptavidin (PDB ident 1MK5) (pink coil) superposed on
T7-SA (blue coil). Biotin (bound in core-streptavidin) is shown
in ball-and-stick representation. The flexible binding loop in
the biotin complex is shown in violet. The missing residues in
this loop in the open conformation in T7-SA are shown as
transparent coil. The major differences between the wild-type
and T7-SA structures, in addition to the additional residues at
the C terminus, involve the conformation of the flexible binding
loop (residues 45-52) and the conformation of residues 24-26
near the a helix.
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Figure 8.
Figure 8. Stereo view showing the overlap of the flexible
binding loop in the wild-type core-streptavidin-biotin complex
(pink bonds) with residues near the C terminus of T7-SA (blue
bonds). Residues 154-156 in T7-SA, while not actually bound in
the biotin-binding site, take on the same conformation and
nearly the same location as the closed loop in the
wild-type-biotin complex.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
356,
738-745)
copyright 2006.
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