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PDBsum entry 1d2f
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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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X-Ray structure of maly from escherichia coli: a pyridoxal 5'-Phosphate-Dependent enzyme acting as a modulator in mal gene expression.
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Authors
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T.Clausen,
A.Schlegel,
R.Peist,
E.Schneider,
C.Steegborn,
Y.S.Chang,
A.Haase,
G.P.Bourenkov,
H.D.Bartunik,
W.Boos.
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Ref.
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EMBO J, 2000,
19,
831-842.
[DOI no: ]
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PubMed id
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Abstract
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MalY represents a bifunctional pyridoxal 5'-phosphate-dependent enzyme acting as
a beta-cystathionase and as a repressor of the maltose regulon. Here we present
the crystal structures of wild-type and A221V mutant protein. Each subunit of
the MalY dimer is composed of a large pyridoxal 5'-phosphate-binding domain and
a small domain similar to aminotransferases. The structural alignment with
related enzymes identifies residues that are generally responsible for
beta-lyase activity and depicts a unique binding mode of the pyridoxal
5'-phosphate correlated with a larger, more flexible substrate-binding pocket.
In a screen for MalY mutants with reduced mal repressor properties, mutations
occurred in three clusters: I, 83-84; II, 181-189 and III, 215-221, which
constitute a clearly distinguished region in the MalY crystal structure far away
from the cofactor. The tertiary structure of one of these mutants (A221V)
demonstrates that positional rearrangements are indeed restricted to regions I,
II and III. Therefore, we propose that a direct protein-protein interaction with
MalT, the central transcriptional activator of the maltose system, underlies
MalY-dependent repression of the maltose system.
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Figure 4.
Figure 4 MalT-binding site. (A) The active dimer of MalY
illustrating the location of the MalT interaction patch. The C^
 traces
of both monomers (white and green) are overlaid with a
transparent surface. The MalT interaction regions are emphasized
by a solid surface that was defined on the basis of the negative
repressor mutants (drawn in red). The PLP cofactor is shown in a
van der Waals representation. Note that the MalT-binding surface
and the active site entrance to the PLP cofactor are located on
opposite sides of the individual MalY monomers. (B) Spatial
structure of the MalT-binding patch, which is constructed from
the three segments I, II and III as described in the text. The C
atoms of segments I, II and III are coloured orange (residues
81–85), white (residues 179–191) and green (residues
212–222), respectively. For each segment, the most important
residue regarding MalT repression (Table II) is labelled. The
model is overlaid with a transparent surface that is colour
coded by atom type. (C) Overlay of the wild-type and A221V MalT
interaction segments I, II and III. The wild-type model and the
corresponding surface are in white, the A221V mutant in green.
Obviously, the mutation Ala221 to Val221 results in a concerted
structural reorientation of all three segments. The orientations
of (B) and (C) are identical.
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Figure 5.
Figure 5 Active site entrances of MalY (left) and CBL (right).
The orientation and scaling of both figures are identical. The
corresponding PLP cofactors are shown in a van der Waals
representation below the surface. Part of the phosphate group of
the MalY cofactor is directly accessible in the active site
cleft.
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The above figures are
reprinted
from an Open Access publication published by Macmillan Publishers Ltd:
EMBO J
(2000,
19,
831-842)
copyright 2000.
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Secondary reference #1
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Title
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Maly of escherichia coli is an enzyme with the activity of a beta c-S lyase (cystathionase).
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Authors
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E.Zdych,
R.Peist,
J.Reidl,
W.Boos.
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Ref.
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J Bacteriol, 1995,
177,
5035-5039.
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PubMed id
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