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PDBsum entry 1gui
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Carbohydrate binding module
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PDB id
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1gui
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References listed in PDB file
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Key reference
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Title
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Differential oligosaccharide recognition by evolutionarily-Related beta-1,4 and beta-1,3 glucan-Binding modules.
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Authors
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A.B.Boraston,
D.Nurizzo,
V.Notenboom,
V.Ducros,
D.R.Rose,
D.G.Kilburn,
G.J.Davies.
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Ref.
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J Mol Biol, 2002,
319,
1143-1156.
[DOI no: ]
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PubMed id
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Abstract
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Enzymes active on complex carbohydrate polymers frequently have modular
structures in which a catalytic domain is appended to one or more
carbohydrate-binding modules (CBMs). Although CBMs have been classified into a
number of families based upon sequence, many closely related CBMs are specific
for different polysaccharides. In order to provide a structural rationale for
the recognition of different polysaccharides by CBMs displaying a conserved
fold, we have studied the thermodynamics of binding and three-dimensional
structures of the related family 4 CBMs from Cellulomonas fimi Cel9B and
Thermotoga maritima Lam16A in complex with their ligands, beta-1,4 and beta-1,3
linked gluco-oligosaccharides, respectively. These two CBMs use a structurally
conserved constellation of aromatic and polar amino acid side-chains that
interact with sugars in two of the five binding subsites. Differences in the
length and conformation of loops in non-conserved regions create binding-site
topographies that complement the known solution conformations of their
respective ligands. Thermodynamics interpreted in the light of structural
information highlights the differential role of water in the interaction of
these CBMs with their respective oligosaccharide ligands.
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Figure 3.
Figure 3. Overlap of the observed oligosaccharide
conformations for the b-1,4 and b-1,3 glucan chains on (a)
CfCBM4-1 and (b) TmCBM4-2 (b;ue) with the solution conformations
for these ligands (green).[31. and 37.] Only the five sugar
units of laminarihexoase making interactions with TmCBM4-2 are
shown.
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Figure 4.
Figure 4. A schematic showing (a) the
CfCBM4-1-cellopentaose interactions and (b)
TmCBM4-2-laminariheptaose interactions. Sugar units that are
structurally-equivalent are shown in red and blue.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2002,
319,
1143-1156)
copyright 2002.
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