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PDBsum entry 2jgo
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De novo protein
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PDB id
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2jgo
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References listed in PDB file
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Key reference
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Title
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Identifying important structural characteristics of arsenic resistance proteins by using designed three-Stranded coiled coils.
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Authors
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D.S.Touw,
C.E.Nordman,
J.A.Stuckey,
V.L.Pecoraro.
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Ref.
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Proc Natl Acad Sci U S A, 2007,
104,
11969-11974.
[DOI no: ]
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PubMed id
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Abstract
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Arsenic, a contaminant of water supplies worldwide, is one of the most toxic
inorganic ions. Despite arsenic's health impact, there is relatively little
structural detail known about its interactions with proteins. Bacteria such as
Escherichia coli have evolved arsenic resistance using the Ars operon that is
regulated by ArsR, a repressor protein that dissociates from DNA when As(III)
binds. This protein undergoes a critical conformational change upon binding
As(III) with three cysteine residues. Unfortunately, structures of ArsR with or
without As(III) have not been reported. Alternatively, de novo designed peptides
can bind As(III) in an endo configuration within a thiolate-rich environment
consistent with that proposed for both ArsR and ArsD. We report the structure of
the As(III) complex of Coil Ser L9C to a 1.8-A resolution, providing x-ray
characterization of As(III) in a Tris thiolate protein environment and allowing
a structural basis by which to understand arsenated ArsR.
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Figure 3.
Fig. 3. The zinc-mediated packing of the coiled coils with
Zn(II) and As(III) ions is shown in pink and cyan, respectively.
(A) Bottom-up view of a central coiled coil (green) with the six
Zn(II) ions that are coordinated by side chains at the
C-terminal end. (B) Side view of the trimeric structure of
As(CSL9C)[3] with a different perspective of the Zn(II)
coordination to the exterior residues of the coiled coils. In
both panels, only two of eight symmetry related Zn(II) ions are
included for clarity.
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Figure 5.
Fig. 5. The overlay of Coil V[a]L[d], shown in green (PDB
entry 1COI), a related parallel three-stranded coiled coil with
As(CSL9C)[3] (red) demonstrates their structural similarity and
highlights their divergence at the C and N termini where the
Zn(II) ions hold CSL9C in a more helical conformation than
V[a]L[d].
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