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PDBsum entry 2wnb
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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 insight into mammalian sialyltransferases.
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Authors
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F.V.Rao,
J.R.Rich,
B.Rakić,
S.Buddai,
M.F.Schwartz,
K.Johnson,
C.Bowe,
W.W.Wakarchuk,
S.Defrees,
S.G.Withers,
N.C.Strynadka.
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Ref.
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Nat Struct Biol, 2009,
16,
1186-1188.
[DOI no: ]
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PubMed id
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Abstract
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Mammalian cell surfaces are modified by complex arrays of glycoproteins,
glycolipids and polysaccharides, many of which terminate in sialic acid and have
central roles in essential processes including cell recognition, adhesion and
immunogenicity. Sialylation of glycoconjugates is performed by a set of
sequence-related enzymes known as sialyltransferases (STs). Here we present the
crystal structure of a mammalian ST, porcine ST3Gal-I, providing a structural
basis for understanding the mechanism and specificity of these enzymes and for
the design of selective inhibitors.
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Figure 1.
Cartoon of pST3Gal-I in complex with product CMP and a
disaccharide sugar acceptor (yellow stick model). A model of the
missing lid (residues 305–316) is shown as dashed line
(magenta) based on an equivalent loop in CstII. The catalytic
base (His319) is highlighted in cyan. (a) The GT29 catalytic
domain is linked to the transmembrane helix by a
protease-sensitive stem region. Residues predicted to be
glycosylated are shown as black sticks. (b) The four conserved
sialyl motifs of GT29 STs.
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Figure 2.
(a) Active site of pST3Gal-I, with CMP occupying the donor
site and Gal  1,3GalNAc
 -PhNO[2]
disaccharide defining the acceptor site (yellow carbon atoms).
Amino acids of interest are shown as sticks, with the catalytic
base represented in cyan. Black dotted lines indicate potential
hydrogen bonds. For Gal 1,3GalNAc
-PhNO[2],
the unbiased 1.25-Å |F[o]| - |F[c]|,  [calc]
electron density map is shown, contoured at 2  .
For CMP, the unbiased 1.55-Å |F[o]| - |F[c]|, [calc]
electron density map is shown, contoured at 2 .
(b) Observed disaccharide acceptor binding in pST3Gal-I (yellow)
with a model of CMP3F-NeuAc (green) based on the
CstII–CMP3F-NeuAc complex (PDB 1RO7)^18.
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The above figures are
reprinted
by permission from Macmillan Publishers Ltd:
Nat Struct Biol
(2009,
16,
1186-1188)
copyright 2009.
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