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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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Structure--Activity relationships of hainantoxin-Iv and structure determination of active and inactive sodium channel blockers.
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Authors
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D.Li,
Y.Xiao,
X.Xu,
X.Xiong,
S.Lu,
Z.Liu,
Q.Zhu,
M.Wang,
X.Gu,
S.Liang.
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Ref.
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J Biol Chem, 2004,
279,
37734-37740.
[DOI no: ]
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PubMed id
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Abstract
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Hainantoxin-IV (HNTX-IV) can specifically inhibit the neuronal
tetrodotoxin-sensitive sodium channels and defines a new class of depressant
spider toxin. The sequence of native HNTX-IV is
ECLGFGKGCNPSNDQCCKSSNLVCSRKHRWCKYEI-NH(2). In the present study, to obtain
further insight into the primary and tertiary structural requirements of
neuronal sodium channel blockers, we determined the solution structure of
HNTX-IV as a typical inhibitor cystine knot motif and synthesized four mutants
designed based on the predicted sites followed by structural elucidation of two
inactive mutants. Pharmacological studies indicated that the S12A and R26A
mutants had activities near that of native HNTX-IV, while K27A and R29A
demonstrated activities reduced by 2 orders of magnitude. (1)H MR analysis
showed the similar molecular conformations for native HNTX-IV and four synthetic
mutants. Furthermore, in the determined structures of K27A and R29A, the side
chains of residues 27 and 29 were located in the identical spatial position to
those of native HNTX-IV. These results suggested that residues Ser(12), Arg(26),
Lys(27), and Arg(29) were not responsible for stabilizing the distinct
conformation of HNTX-IV, but Lys(27) and Arg(29) were critical for the
bioactivities. The potency reductions produced by Ala substitutions were
primarily due to the direct interaction of the essential residues Lys(27) and
Arg(29) with sodium channels rather than to a conformational change. After
comparison of these structures and activities with correlated toxins, we
hypothesized that residues Lys(27), Arg(29), His(28), Lys(32), Phe(5), and
Trp(30) clustered on one face of HNTX-IV were responsible for ligand binding.
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Figure 2.
FIG. 2. Structural comparison of HNTX-IV and correlated
toxin molecules. A, ensembles of 20 energy-refined conformers
representing the solution structures of native HNTX-IV, K27A,
and R29A. The backbones are shown in cyan, green, and gray,
respectively. Positively charged side chains are shown in blue,
and negatively charged side chains are shown in red. B,
comparison of HNTX-IV to conotoxin GS (CTX-GS) and
µ-conotoxin GIIIA (CTX-GIIIA) (conotoxin GS, Protein Data
Bank code 1AG7 [PDB]
; µ-conotoxin GIIIA, Protein Data Bank code 1TCG [PDB]
). The  -sheet is shown in
yellow, the turn is shown in blue, and the random coil structure
is shown in green. Three disulfide bonds of each molecule are
indicated. The letters N and C refer to the amino and carboxyl
termini, respectively.
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Figure 7.
FIG. 7. Solution structure characterization of HNTX-IV. A,
surface profile of HNTX-IV. a, surface profile of predicted
active sites. b, surface profile of putative active sites. Blue,
mauve, and cyan regions represent positively charged, polar, and
hydrophobic residues, respectively. B, backbone superposition of
native HNTX-IV (blue), K27A (green), and R29A (red). 27 and 29
indicate the positions of substituted amino acid residues. The
fit was done using the common secondary structure elements. The
letters N and C refer to the amino and carboxyl termini,
respectively.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2004,
279,
37734-37740)
copyright 2004.
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Secondary reference #1
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Title
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Synthesis and oxidative refolding of hainantoxin-Iv
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Authors
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Z.H.Liu,
P.Chen,
S.P.Liang.
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Ref.
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acta biochim biophys sinica, 2002,
34,
516.
[DOI no: ]
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PubMed id
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Figure 2.
FIG. 2. Structural comparison of HNTX-IV and correlated
toxin molecules. A, ensembles of 20 energy-refined conformers
representing the solution structures of native HNTX-IV, K27A,
and R29A. The backbones are shown in cyan, green, and gray,
respectively. Positively charged side chains are shown in blue,
and negatively charged side chains are shown in red. B,
comparison of HNTX-IV to conotoxin GS (CTX-GS) and
µ-conotoxin GIIIA (CTX-GIIIA) (conotoxin GS, Protein Data
Bank code 1AG7 [PDB]
; µ-conotoxin GIIIA, Protein Data Bank code 1TCG [PDB]
). The -sheet is shown in
yellow, the turn is shown in blue, and the random coil structure
is shown in green. Three disulfide bonds of each molecule are
indicated. The letters N and C refer to the amino and carboxyl
termini, respectively.
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Figure 7.
FIG. 7. Solution structure characterization of HNTX-IV. A,
surface profile of HNTX-IV. a, surface profile of predicted
active sites. b, surface profile of putative active sites. Blue,
mauve, and cyan regions represent positively charged, polar, and
hydrophobic residues, respectively. B, backbone superposition of
native HNTX-IV (blue), K27A (green), and R29A (red). 27 and 29
indicate the positions of substituted amino acid residues. The
fit was done using the common secondary structure elements. The
letters N and C refer to the amino and carboxyl termini,
respectively.
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The above figures are
reproduced from the cited reference
with permission from the ASBMB
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Secondary reference #2
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Title
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Isolation and characterization of hainantoxin-Iv, A novel antagonist of tetrodotoxin-Sensitive sodium channels from the chinese bird spider selenocosmia hainana.
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Authors
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Z.Liu,
J.Dai,
Z.Chen,
W.Hu,
Y.Xiao,
S.Liang.
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Ref.
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Cell Mol Life Sci, 2003,
60,
972-978.
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PubMed id
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