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PDBsum entry 2kn2
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Metal binding protein
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PDB id
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2kn2
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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 studies of soybean calmodulin isoform 4 bound to the calmodulin-Binding domain of tobacco mitogen-Activated protein kinase phosphatase-1 provide insights into a sequential target binding mode.
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Authors
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H.Ishida,
M.Rainaldi,
H.J.Vogel.
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Ref.
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J Biol Chem, 2009,
284,
28292-28305.
[DOI no: ]
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PubMed id
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Abstract
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The calcium regulatory protein calmodulin (CaM) binds in a calcium-dependent
manner to numerous target proteins. The calmodulin-binding domain (CaMBD) region
of Nicotiana tabacum MAPK phosphatase has an amino acid sequence that does not
resemble the CaMBD of any other known Ca(2+)-CaM-binding proteins. Using a
unique fusion protein strategy, we have been able to obtain a high resolution
solution structure of the complex of soybean Ca(2+)-CaM4 (SCaM4) and this CaMBD.
Complete isotope labeling of both parts of the complex in the fusion protein
greatly facilitated the structure determination by NMR. The 12-residue CaMBD
region was found to bind exclusively to the C-lobe of SCaM4. A specific Trp and
Leu side chain are utilized to facilitate strong binding through a novel "double
anchor" motif. Moreover, the orientation of the helical peptide on the surface
of Ca(2+)-SCaM4 is distinct from other known complexes. The N-lobe of
Ca(2+)-SCaM4 in the complex remains free for additional interactions and could
possibly act as a calcium-dependent adapter protein. Signaling through the MAPK
pathway and increases in intracellular Ca(2+) are both hallmarks of the plant
stress response, and our data support the notion that coordination of these
responses may occur through the formation of a unique CaM-MAPK phosphatase
multiprotein complex.
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Figure 4.
a, backbones of 30 structures of SCaM4CT-NtMKP1 are
superimposed for the well-folded region (residue 80–163). The
SCaM4CT and NtMKP1 domain are shown in navy and yellow,
respectively, while the poly-Gly linker region is shown in gray.
b, ribbon representations of the structure with the lowest
energy. The hydrophobic side chains of Trp^157, Leu^160, and
Phe^164 are displayed.
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Figure 5.
a, local interactions between SCaM4CT residues and the anchor
residues of the NtMKP1 domain, Trp^157 and Leu^160. The side
chains of the SCaM4CT and NtMKP1 domains are colored in purple
and green, respectively. b, schematic showing observed NOEs
between SCaM4CT and NtMKP1 domain.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2009,
284,
28292-28305)
copyright 2009.
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