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PDBsum entry 2qf5
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Structural protein
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PDB id
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2qf5
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References listed in PDB file
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Key reference
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Title
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High-Resolution structure of the major periplasmic domain from the cell shape-Determining filament mrec.
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Authors
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A.L.Lovering,
N.C.Strynadka.
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Ref.
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J Mol Biol, 2007,
372,
1034-1044.
[DOI no: ]
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PubMed id
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Abstract
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Bacterial cell shape is dictated by the cell wall, a plastic structure that must
adapt to growth and division whilst retaining its function as a selectively
permeable barrier. The modulation of cell wall structure is achieved by a
variety of enzymatic functions, all of which must be spatially regulated in a
precise manner. The membrane-spanning essential protein MreC has been identified
as the central hub in this process, linking the bacterial cytoskeleton to a
variety of cell wall-modifying enzymes. Additionally, MreC can form filaments,
believed to run perpendicularly to the membrane. We present here the 1.2 A
resolution crystal structure of the major periplasmic domain of Streptococcus
pneumoniae MreC. The protein shows a novel arrangement of two barrel-shaped
domains, one of which shows homology to a known protein oligomerization motif,
with the other resembling a catalytic domain from a bacterial protease. We
discuss the implications of these results for MreC function, and detail the
structural features of the molecule that may be responsible for the binding of
partner proteins.
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Figure 2.
Figure 2. Non-crystallographic symmetry interactions of the
MreC major periplasmic domain. (a) Interaction of MreC molecules
and sheet completion from the barrel 1 β1 region. The two
molecules in the P2[1]2[1]2[1] asymmetric unit are shown, with
strand β1 represented in stick form. Chain A (orange) and chain
B (yellow) form an intricate arrangement, with an antiparallel
β-sheet that has edges composed of β1 from each monomer. The
interaction is centered around residue K112. (b) Interaction of
MreC molecules at the axial edge of barrel 2. The
crystallographic 2-fold axis of the C2 crystal form is shown,
with symmetry-related molecules colored in alternate yellow and
orange. This interaction is composed of the exposed hydrophobic
Y190 and L225 residues, and four asparagine residues (all
represented in stick form). These six positions show a
preference for hydrophobic amino acids (Figure 6).
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Figure 4.
Figure 4. Alignment with structural homologs. Precise details
and statistics of alignment are given in the text. (a) Overlay
of the MreC barrel 1 with the ribosomal RNA-modifying complex
protein Gar1.^15 For clarity, an orthogonal view is shown as an
inset. MreC (blue) and Gar1 (gold) possess identical topology,
and both the N and C-terminal loops are exposed in both
structures. (b) Overlay of the MreC barrel 2 with the C-terminal
barrel of α-lytic protease.^16 MreC (blue) and α-lytic
protease (gold) overlap well in their respective barrel 2
regions, but the barrel–barrel topologies differ between the
two folds; MreC places the C-terminal loops of barrel 2 away
from barrel 1, whereas in α-lytic protease the C-terminal
region of barrel 2 is placed against barrel 1, forming the
active site.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2007,
372,
1034-1044)
copyright 2007.
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