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PDBsum entry 2gnt
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Sugar binding protein
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PDB id
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2gnt
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References listed in PDB file
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Key reference
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Title
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Interplay between metal binding and cis/trans isomerization in legume lectins: structural and thermodynamic study of p. Angolensis lectin.
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Authors
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A.Garcia-Pino,
L.Buts,
L.Wyns,
R.Loris.
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Ref.
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J Mol Biol, 2006,
361,
153-167.
[DOI no: ]
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PubMed id
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Abstract
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The interplay between metal binding, carbohydrate binding activity, stability
and structure of the lectin from Pterocarpus angolensis was investigated.
Removal of the metals leads to a more flexible form of the protein with
significantly less conformational stability. Crystal structures of this
metal-free form show significant structural rearrangements, although some
structural features that allow the binding of sugars are retained. We propose
that substitution of an asparagine residue at the start of the C-terminal
beta-strand of the legume lectin monomer hinders the trans-isomerization of the
cis-peptide bond upon demetallization and constitutes an intramolecular switch
governing the isomer state of the non-proline bond and ultimately the lectin
phenotype.
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Figure 4.
Figure 4. Demetallization-induced structural changes on
apo-PAL. (a) Stereo view of the superposition of holo-PAL (chain
B from pdb entry 1ukg) on apo-PAL (chain B). The metal binding
loop is coloured cyan for holo-PAL and blue for apo-PAL. (b)
Stereo view of the superposition of the metal binding loop of
holo-PAL (grey) on apo-PAL (in blue). Calcium ions are shown as
yellow spheres and manganese ions as green spheres.
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Figure 7.
Figure 7. A sequence-dependent intramolecular switch
determines the cis/trans isomerization of metal-free legume
lectins. (a) Stereo view of the carbohydrate binding sites and
the C-terminal β-strands of apo-PAL (coloured according to atom
type), apo-GS-IB4^15 (red) and apo-con A^11 (yellow)
superimposed on each other. The hydrogen bonds between Asp208
and Asn104 in apo-con A are indicated by broken lines. (b)
Stereo view of an equivalent superposition for apo-PAL (coloured
according to atom type), ERGIC 53^38 (blue), Arcelin-1^36 (light
green) and Arcelin-5^35 (dark green).
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
361,
153-167)
copyright 2006.
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