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PDBsum entry 1id0
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Contents |
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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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Structural and mutational analysis of the phoq histidine kinase catalytic domain. Insight into the reaction mechanism.
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Authors
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A.Marina,
C.Mott,
A.Auyzenberg,
W.A.Hendrickson,
C.D.Waldburger.
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Ref.
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J Biol Chem, 2001,
276,
41182-41190.
[DOI no: ]
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PubMed id
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Abstract
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PhoQ is a transmembrane histidine kinase belonging to the family of
two-component signal transducing systems common in prokaryotes and lower
eukaryotes. In response to changes in environmental Mg(2+) concentration, PhoQ
regulates the level of phosphorylated PhoP, its cognate transcriptional
response-regulator. The PhoQ cytoplasmic region comprises two independently
folding domains: the histidine-containing phosphotransfer domain and the
ATP-binding kinase domain. We have determined the structure of the kinase domain
of Escherichia coli PhoQ complexed with the non-hydrolyzable ATP analog
adenosine 5'-(beta,gamma-imino)triphosphate and Mg(2+). Nucleotide binding
appears to be accompanied by conformational changes in the loop that surrounds
the ATP analog (ATP-lid) and has implications for interactions with the
substrate phosphotransfer domain. The high resolution (1.6 A) structure reveals
a detailed view of the nucleotide-binding site, allowing us to identify
potential catalytic residues. Mutagenic analyses of these residues provide new
insights into the catalytic mechanism of histidine phosphorylation in the
histidine kinase family. Comparison with the active site of the related GHL
ATPase family reveals differences that are proposed to account for the distinct
functions of these proteins.
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Figure 3.
Fig. 3. ATP-lid movement in PhoQ-KD nucleotide-bound
structure. Superimposition of C  traces from
PhoQ-KD (blue) and CheA-KD (yellow) shows the ATP-lid
displacement toward the main  -sheet in
PhoQ (closed conformation). The AMPPNP molecule is shown in
magenta. Glycine C atoms are
shown as spheres, and side chains of the hydrophobic patch
residues are shown as sticks. Selected residues are labeled for
each protein in the color corresponding to the backbone trace.
hairpin
movement and the conserved Gly in the hairpin are also indicated.
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Figure 4.
Fig. 4. AMPPNP binding site. Upper panel, plot of the
interactions between AMPPNP-Mg2+ and the protein drawn with the
program LIGPLOT (40). Lower panel, stereoview of structural
elements that form the ATP binding site in PhoQ-KD. Helices and
strands are partially transparent with the same colors as in
Fig. 1A. the AMPPNP molecule (yellow) and interacting side
chains (green) are depicted as ball-and-stick with the same
colors as in upper panel. Carbon, nitrogen, oxygen, and
phosphate are drawn in gray, blue, red, and black, respectively.
Water molecules are cyan spheres, and the Mg2+ ion is a green
sphere. Hydrogen bonds are shown as dotted magenta lines and the
magnesium coordination as dotted black lines.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2001,
276,
41182-41190)
copyright 2001.
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