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PDBsum entry 2zzv
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Transport protein
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PDB id
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2zzv
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References listed in PDB file
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Key reference
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Title
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Crystal structure of a periplasmic substrate-Binding protein in complex with calcium lactate.
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Authors
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N.Akiyama,
K.Takeda,
K.Miki.
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Ref.
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J Mol Biol, 2009,
392,
559-565.
[DOI no: ]
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PubMed id
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Abstract
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Lactate is utilized in many biological processes, and its transport across
biological membranes is mediated with various types of transporters. Here, we
report the crystal structures of a lactate-binding protein of a TRAP (tripartite
ATP-independent periplasmic) secondary transporter from Thermus thermophilus
HB8. The folding of the protein is typical for a type II periplasmic
solute-binding protein and forms a dimer in a back-to-back manner. One molecule
of l-lactate is clearly identified in a cleft of the protein as a complex with a
calcium ion. Detailed crystallographic and biochemical analyses revealed that
the calcium ion can be removed from the protein and replaced with other divalent
cations. This characterization of the structure of a protein binding with
calcium lactate makes a significant contribution to our understanding of the
mechanisms by which calcium and lactate are accommodated in cells.
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Figure 2.
Fig. 2. Crystal structure of TTHA0766 from T. thermophilus
HB8. (a) The monomer structure is represented as a ribbon model,
in which domains I and II are shown in green and magenta,
respectively. The additional C-terminal helices are shown in
yellow. Liganded calcium ion and lactate molecule are shown as
CPK and stick models, respectively. (b) Side view of (a) rotated
by 90° around the vertical axis. (c) The dimer structure is
represented as a tube model. Chain A, cyan; chain B, gray. (d)
Interprotomer interactions. The side chains involved in the
interactions are shown as sticks. Asterisks denote residues of
another subunit. Salt bridges are indicated as orange dashed
lines.
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Figure 4.
Fig. 4. Structural features of the form II and III crystals.
(a) The anomalous difference Fourier maps of form II are shown
at the 3σ and 6σ levels as red and blue meshes, respectively.
Maps were calculated using the refined phases of form II (Table
1) and the amplitude of structure factors from the data sets
collected at low-remote (λ = 1.2896 Å), peak (λ = 1.2810
Å) and high-remote wavelengths (λ = 1.2569 Å) of
zinc (Table S1). (b) The binding site of form II. (c) The
binding site of form III. The structure of form I is
superimposed as a semitransparent model in gray for comparison
of (b) and (c).
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2009,
392,
559-565)
copyright 2009.
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