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PDBsum entry 2fx0
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Transcription
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PDB id
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2fx0
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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 bacillus cereus hlyiir, A transcriptional regulator of the gene for pore-Forming toxin hemolysin ii.
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Authors
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O.V.Kovalevskiy,
A.A.Lebedev,
A.K.Surin,
A.S.Solonin,
A.A.Antson.
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Ref.
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J Mol Biol, 2007,
365,
825-834.
[DOI no: ]
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PubMed id
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Abstract
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Production of Bacillus cereus and Bacillus anthracis toxins is controlled by a
number of transcriptional regulators. Here we report the crystal structure of B.
cereus HlyIIR, a regulator of the gene encoding the pore-forming toxin hemolysin
II. We show that HlyIIR forms a tight dimer with a fold and overall architecture
similar to the TetR family of repressors. A remarkable feature of the structure
is a large internal cavity with a volume of 550 A(3) suggesting that the
activity of HlyIIR is modulated by binding of a ligand, which triggers the toxin
production. Virtual ligand library screening shows that this pocket can
accommodate compounds with molecular masses of up to 400-500 Da. Based on
structural data and previous biochemical evidence, we propose a model for HlyIIR
interaction with the DNA.
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Figure 1.
Figure 1. The HlyIIR structure. (a) Electron density
corresponding to one of the protein helices (α1) calculated
with maximum likelihood weighted coefficients 2|F[o]|–|F[c]|
and contoured at 1.25σ. (b) and (c) Ribbon diagrams of HlyIIR.
Monomer (b) is rainbow-coloured with its N-terminal in red and
C-terminal in blue. Dotted line indicates the disordered
segment, which was not modelled. The biological dimer (c) is
generated by the crystallographic 2-fold axis. The large
internal cavity (yellow) is drawn along the van der Waals radii
of cavity-forming residues. The cavity surface was calculated by
SURFNET.^33 This Figure and Figure 3 and Figure 4 were prepared
using CCP4MG.^34
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Figure 3.
Figure 3. Ligand-binding pocket. (a) Stereo view with the
cavity contoured as in Figure 1(c) and cavity-lining residues
shown by sticks. The compound that gave a highest score during
the AutoDock screening (NCI 23904) is shown with its carbon
atoms in brown, oxygen atoms in pink and nitrogen atoms in light
blue. (b) Difference electron density maps (green) corresponding
to the pocket area and contoured at 3σ.
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The above figures are
reprinted
from an Open Access publication published by Elsevier:
J Mol Biol
(2007,
365,
825-834)
copyright 2007.
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