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PDBsum entry 2x0d
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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 basis of substrate binding in wsaf, A rhamnosyltransferase from geobacillus stearothermophilus.
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Authors
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K.Steiner,
G.Hagelueken,
P.Messner,
C.Schäffer,
J.H.Naismith.
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Ref.
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J Mol Biol, 2010,
397,
436-447.
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PubMed id
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Abstract
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Carbohydrate polymers are medically and industrially important. The S-layer of
many Gram-positive organisms comprises protein and carbohydrate polymers and
forms an almost paracrystalline array on the cell surface. Not only is this
array important for the bacteria but it has potential application in the
manufacture of commercially important polysaccharides and glycoconjugates as
well. The S-layer glycoprotein glycan from Geobacillus stearothermophilus NRS
2004/3a is mainly composed of repeating units of three rhamnose sugars linked by
alpha-1,3-, alpha-1,2-, and beta-1,2-linkages. The formation of the
beta-1,2-linkage is catalysed by the enzyme WsaF. The rational use of this
system is hampered by the fact that WsaF and other enzymes in the pathway share
very little homology to other enzymes. We report the structural and biochemical
characterisation of WsaF, the first such rhamnosyltransferase to be
characterised. Structural work was aided by the surface entropy reduction
method. The enzyme has two domains, the N-terminal domain, which binds the
acceptor (the growing rhamnan chain), and the C-terminal domain, which binds the
substrate (dTDP-beta-l-rhamnose). The structure of WsaF bound to dTDP and
dTDP-beta-l-rhamnose coupled to biochemical analysis identifies the residues
that underlie catalysis and substrate recognition. We have constructed and
tested by site-directed mutagenesis a model for acceptor recognition.
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