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PDBsum entry 2fmh
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Signaling protein
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PDB id
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2fmh
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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 structures of beryllium fluoride-Free and beryllium fluoride-Bound chey in complex with the conserved c-Terminal peptide of chez reveal dual binding modes specific to chey conformation.
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Authors
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J.Guhaniyogi,
V.L.Robinson,
A.M.Stock.
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Ref.
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J Mol Biol, 2006,
359,
624-645.
[DOI no: ]
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PubMed id
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Abstract
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Chemotaxis, the environment-specific swimming behavior of a bacterial cell is
controlled by flagellar rotation. The steady-state level of the phosphorylated
or activated form of the response regulator CheY dictates the direction of
flagellar rotation. CheY phosphorylation is regulated by a fine equilibrium of
three phosphotransfer activities: phosphorylation by the kinase CheA, its
auto-dephosphorylation and dephosphorylation by its phosphatase CheZ. Efficient
dephosphorylation of CheY by CheZ requires two spatially distinct
protein-protein contacts: tethering of the two proteins to each other and
formation of an active site for dephosphorylation. The former involves
interaction of phosphorylated CheY with the small highly conserved C-terminal
helix of CheZ (CheZ(C)), an indispensable structural component of the functional
CheZ protein. To understand how the CheZ(C) helix, representing less than 10% of
the full-length protein, ascertains molecular specificity of binding to CheY, we
have determined crystal structures of CheY in complex with a synthetic peptide
corresponding to 15 C-terminal residues of CheZ (CheZ(200-214)) at resolutions
ranging from 2.0 A to 2.3A. These structures provide a detailed view of the
CheZ(C) peptide interaction both in the presence and absence of the phosphoryl
analog, BeF3-. Our studies reveal that two different modes of binding the
CheZ(200-214) peptide are dictated by the conformational state of CheY in the
complex. Our structures suggest that the CheZ(C) helix binds to a "meta-active"
conformation of inactive CheY and it does so in an orientation that is distinct
from the one in which it binds activated CheY. Our dual binding mode hypothesis
provides implications for reverse information flow in CheY and extends previous
observations on inherent resilience in CheY-like signaling domains.
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Figure 3.
Figure 3. The CheZ[200-214] peptide-CheY interface. Ribbon
representation of (a) the F432YZ[200-214] interface and (b) the
P2(1)2(1)2YZ[200-214] interface. The side-chains of key
contacting residues are illustrated as ball and stick models and
hydrophobic contacts are shown as green patches. (c) Relative
B-factors of CheZ[200-214] in the CheY-CheZ[200-214] structures.
The relative B-factor versus CheZ residue number plot in Click
to view the MathML source- [0?wchp=dGLbVlb-zSkzk]
-free F432YZ[200-214] is shown in cyan, that in Click to view
the MathML source- [0?wchp=dGLbVlb-zSkzk]
-bound F432YZ[200-214] in deep blue and that in Click to view
the MathML source- [0?wchp=dGLbVlb-zSkzk]
-bound P2(1)2(1)2YZ[200-214] in orange. B[residue] is the
overall B-factor for each residue and B[CheZ] is the overall
B-factor for all atoms of CheZ[200-214] included in the final
model. (d) Schematic representation of the CheY-CheZ[200-214]
contacts. The F432Z[200-214] primary sequence in cyan and the
P2(1)2(1)2Z[200-214] primary sequence in orange are shown on
either side of the C-terminal half of CheY, represented in
secondary structural elements. Participating residues are
highlighted. Hydrophobic contacts are illustrated as continuous
grey lines, salt bridges as broken black lines and hydrogen
bonds as continuous black lines. The Click to view the MathML
source- [0?wchp=dGLbVlb-zSkzk]
-free and Click to view the MathML source- [0?wchp=dGLbVlb-zSkzk]
-bound F432YZ[200-214] structures solved from crystals grown in
Tris (pH 8.4) are used as representatives of F432YZ[200-214]
structures in this Figure.
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Figure 4.
Figure 4. Ribbon diagrams of CheY-CheZ[C] structures upon
superposition of CheY showing different orientations of CheZ[C].
CheY molecules in F432YZ[200-214], P2(1)2(1)2YZ[200-214] and
CheY-CheZ[1-214]15 structures are shown in light gray and the
respective CheZ[C] helices are shown in cyan, orange and
magenta, respectively. The Click to view the MathML source- [0?wchp=dGLbVlb-zSkzk]
-free F432YZ[200-214] structure solved from a crystal grown in
Tris (pH 8.4) is used in this Figure as a representative of all
six F432YZ[200-214] structures.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
359,
624-645)
copyright 2006.
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