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PDBsum entry 2d7r
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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 carbohydrate transfer activity by human udp-Galnac: polypeptide alpha-N-Acetylgalactosaminyltransferase (pp-Galnac-T10).
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Authors
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T.Kubota,
T.Shiba,
S.Sugioka,
S.Furukawa,
H.Sawaki,
R.Kato,
S.Wakatsuki,
H.Narimatsu.
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Ref.
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J Mol Biol, 2006,
359,
708-727.
[DOI no: ]
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PubMed id
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Abstract
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Mucin-type O-glycans are important carbohydrate chains involved in
differentiation and malignant transformation. Biosynthesis of the O-glycan is
initiated by the transfer of N-acetylgalactosamine (GalNAc) which is catalyzed
by UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases
(pp-GalNAc-Ts). Here we present crystal structures of the pp-GalNAc-T10 isozyme,
which has specificity for glycosylated peptides, in complex with the hydrolyzed
donor substrate UDP-GalNAc and in complex with GalNAc-serine. A structural
comparison with uncomplexed pp-GalNAc-T1 suggests that substantial
conformational changes occur in two loops near the catalytic center upon donor
substrate binding, and that a distinct interdomain arrangement between the
catalytic and lectin domains forms a narrow cleft for acceptor substrates. The
distance between the catalytic center and the carbohydrate-binding site on the
lectin beta sub-domain influences the position of GalNAc glycosylation on
GalNAc-glycosylated peptide substrates. A chimeric enzyme in which the two
domains of pp-GalNAc-T10 are connected by a linker from pp-GalNAc-T1 acquires
activity toward non-glycosylated acceptors, identifying a potential mechanism
for generating the various acceptor specificities in different isozymes to
produce a wide range of O-glycans.
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Figure 3.
Figure 3. Binding pocket for the donor substrate. UDP,
GalNAc and Mn^2+ are shown in ball-and-stick representation in
the same colors as for Figure 2. Amino acid residues interacting
with the donor substrate are shown in a line representation
(carbon atoms, green). Hydrogen-bonding interactions are shown
as black broken lines. The coordinate bonds to Mn^2+ are
represented as red broken lines. The oxygen atom of water
molecule that coordinates the Mn^2+ is labeled with Wt. (a) and
(b) Two views corresponding to those shown in Figure 2(a) and
(b), respectively.
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Figure 8.
Figure 8. Interactions between the catalytic domain, the
linker region and the lectin domain. Ball-and-stick
representations indicate residues responsible for the
interactions, which are shown in red, blue and magenta for the
catalytic domain, the linker region and the lectin domain,
respectively. (a) pp-GalNAc-T10. Residues Asp289, Trp290,
Lys295, Ile297, Pro298, Tyr404 and Arg408 are shown in red,
Phe449TyrProProValGluProProAlaAlaAlaTrp460 in blue, and Thr504,
Phe505, Trp507, Arg508, Ser540, Phe589, His591, Thr592, Asn593
and Val596 in magenta. (b) pp-GalNAc-T1. Residues Tyr256,
Phe259, Trp261, Tyr268, Arg273, Met374, Phe377, Phe380, Ile383
and Glu416 are shown in red,
Asp421SerGlnIleProArgHisTyrPheSerLeu431 in blue, and Gly464,
Val467, Ser469, Tyr470, Thr471, Ala472, Arg477, Asp479, His499,
Asn552 and Val553 in magenta.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
359,
708-727)
copyright 2006.
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