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PDBsum entry 2wn2
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Cell adhesion
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PDB id
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2wn2
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References listed in PDB file
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Key reference
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Title
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Discoidin i from dictyostelium discoideum and interactions with oligosaccharides: specificity, Affinity, Crystal structures, And comparison with discoidin ii.
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Authors
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S.V.Mathieu,
K.S.Aragão,
A.Imberty,
A.Varrot.
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Ref.
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J Mol Biol, 2010,
400,
540-554.
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PubMed id
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Abstract
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Discoidin I and Discoidin II (DiscI and DiscII), are
N-acetylgalactosamine-binding proteins from Dictyostelium discoideum. They
consist of two domains with an N-terminal discoidin domain and a C-terminal
H-type lectin domain. They were cloned and expressed in high yield in
recombinant form in Escherichia coli. Although both lectins bind galactose and
N-acetylgalactosamine, glycan array experiments performed on the recombinant
proteins displayed strong differences in their specificity for oligosaccharides.
DiscI and DiscII bind preferentially to Gal/GalNAcbeta1-3Gal/GalNAc-and
Gal/GalNAcbeta1-4GlcNAcbeta1-6Gal/GalNAc-containing glycans respectively. The
affinity of the interaction of DiscI with monosaccharides and disaccharides was
evaluated using isothermal calorimetry experiments. The tree-dimensional
structures of native DiscI and its complexes with GalNAc, GalNAcbeta1-3Gal and
Galbeta1-3GalNAc were solved by X-ray crystallography. DiscI forms trimers with
involvement of calcium at the monomer interface. The N-terminal discoidin domain
presents structural similarity to F-type lectins such as the eel agglutinin
where an amphiphilic binding pocket suggests a possible carbohydrate-binding
activity. In the C-terminal H-type lectin domain, the GalNAc residue establishes
specific hydrogen bonds that explain the observed affinity (K(d)= 3 10(-4) M).
The different specificities of DiscI and DiscII for oligosaccharides were
rationalized from the different structures obtained by either X-ray
crystallography or molecular modelling.
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