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PDBsum entry 1mw2
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Oligosaccharide and sucrose complexes of amylosucrase. Structural implications for the polymerase activity.
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Authors
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L.K.Skov,
O.Mirza,
D.Sprogøe,
I.Dar,
M.Remaud-Simeon,
C.Albenne,
P.Monsan,
M.Gajhede.
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Ref.
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J Biol Chem, 2002,
277,
47741-47747.
[DOI no: ]
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PubMed id
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Abstract
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The glucosyltransferase amylosucrase is structurally quite similar to the
hydrolase alpha-amylase. How this switch in functionality is achieved is an
important and fundamental question. The inactive E328Q amylosucrase variant has
been co-crystallized with maltoheptaose, and the structure was determined by
x-ray crystallography to 2.2 A resolution, revealing a maltoheptaose binding
site in the B'-domain somewhat distant from the active site. Additional soaking
of these crystals with maltoheptaose resulted in replacement of Tris in the
active site with maltoheptaose, allowing the mapping of the -1 to +5 binding
subsites. Crystals of amylosucrase were soaked with sucrose at different
concentrations. The structures at approximately 2.1 A resolution revealed three
new binding sites of different affinity. The highest affinity binding site is
close to the active site but is not in the previously identified substrate
access channel. Allosteric regulation seems necessary to facilitate access from
this binding site. The structures show the pivotal role of the B'-domain in the
transferase reaction. Based on these observations, an extension of the hydrolase
reaction mechanism valid for this enzyme can be proposed. In this mechanism, the
glycogen-like polymer is bound in the widest access channel to the active site.
The polymer binding introduces structural changes that allow sucrose to migrate
from its binding site into the active site and displace the polymer.
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Figure 1.
Fig. 1. Stereo picture illustrating the various sucrose-
and oligosaccharide binding sites on amylosucrase. The three
oligosacchararide binding sites are labeled OB1, OB2, and OB3.
Sucrose at the surface site is colored magenta and labeled SB2.
The B'-domain is colored yellow.
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Figure 5.
Fig. 5. Schematic representation of the interactions at
the AS·sucrose binding site (SB2).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2002,
277,
47741-47747)
copyright 2002.
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Secondary reference #1
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Title
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Amylosucrase, A glucan-Synthesizing enzyme from the alpha-Amylase family.
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Authors
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L.K.Skov,
O.Mirza,
A.Henriksen,
G.P.De montalk,
M.Remaud-Simeon,
P.Sarçabal,
R.M.Willemot,
P.Monsan,
M.Gajhede.
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Ref.
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J Biol Chem, 2001,
276,
25273-25278.
[DOI no: ]
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PubMed id
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Figure 1.
Fig. 1. Schematic representation of the AS structure with
labeling and color-coding of the five domains. N, dark blue; A,
light blue; B, yellow; B', magenta; and C, red. The two
catalytically active residues (Asp^286 and Glu^328) are also
shown. They are located at the end of the barrel  -strand 4
and at the tip of -strand 5,
respectively. The figure was produced with MOLSCRIPT (36) and
Raster3D (37).
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Figure 6.
Fig. 6. Drawing of the solvent accessible surface of AS
near the pocket opening. The B'-domain is colored dark gray. The
O4L of the superimposed modified acarbose is colored white
indicating the positions of the TAKA-amylase subsites.
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The above figures are
reproduced from the cited reference
with permission from the ASBMB
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Secondary reference #2
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Title
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Crystal structures of amylosucrase from neisseria polysaccharea in complex with d-Glucose and the active site mutant glu328gln in complex with the natural substrate sucrose.
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Authors
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O.Mirza,
L.K.Skov,
M.Remaud-Simeon,
G.Potocki de montalk,
C.Albenne,
P.Monsan,
M.Gajhede.
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Ref.
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Biochemistry, 2001,
40,
9032-9039.
[DOI no: ]
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PubMed id
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