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PDBsum entry 2aj1
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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 basis for metal binding specificity: the n-Terminal cadmium binding domain of the p1-Type atpase cada.
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Authors
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L.Banci,
I.Bertini,
S.Ciofi-Baffoni,
X.C.Su,
R.Miras,
N.Bal,
E.Mintz,
P.Catty,
J.E.Shokes,
R.A.Scott.
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Ref.
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J Mol Biol, 2006,
356,
638-650.
[DOI no: ]
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PubMed id
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Abstract
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In bacteria, P1-type ATPases are responsible for resistance to di- and
monovalent toxic heavy metals by taking them out of the cell. These ATPases have
a cytoplasmic N terminus comprising metal binding domains defined by a
betaalphabetabetaalphabeta fold and a CXXC metal binding motif. To check how the
structural properties of the metal binding site in the N terminus can influence
the metal specificity of the ATPase, the first structure of a Cd(II)-ATPase N
terminus was determined by NMR and its coordination sphere was investigated by
X-ray absorption spectroscopy. A novel metal binding environment was found,
comprising the two conserved Cys residues of the metal binding motif and a Glu
in loop 5. A bioinformatic search identifies an ensemble of highly homologous
sequences presumably with the same function. Another group of highly homologous
sequences is found which can be referred to as zinc-detoxifying P1-type ATPases
with the metal binding pattern DCXXC in the N terminus. Because no carboxylate
groups participate in Cu(I) or Ag(I) binding sites, we suggest that the acidic
residue plays a key role in the coordination properties of divalent cations,
hence conferring a function to the N terminus in the metal specificity of the
ATPase.
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Figure 5.
Figure 5. (a) Cd K edge spectra and (b) Fourier transforms
(k3 weighting, k=2-13 Å -1) for CadA NTKII (continuous)
and CadA NTKII+TCEP (broken). k3-weighted EXAFS data are
presented in the inset to (b).
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Figure 7.
Figure 7. Solution structures of N-terminal metal-binding
domains of L. monocytogenes CadA, E. coli ZntA (1MWY) and B.
subtilis CopA (1JWW). Apo forms of the proteins, marked with an
asterisk in Figure 3, are compared here. van der Waals contacts
involving some hydrophobic residues are shown in blue, the metal
ligands are shown in yellow and some highly conserved residues
are in red. The Gly residues, shaded in cyan in Figure 3, are
mapped in cyan on the backbone of the structures.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
356,
638-650)
copyright 2006.
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