 |
PDBsum entry 1m2s
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
The solution structure of bmtx3b, A member of the scorpion toxin subfamily alpha-Ktx 16.
|
|
|
Authors
|
|
Y.Wang,
X.Chen,
N.Zhang,
G.Wu,
H.Wu.
|
|
|
Ref.
|
|
Proteins, 2005,
58,
489-497.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
This article reports the solution structure of BmTx3B (alpha-KTx16.2), a
potassium channel blocker belonging to the subfamily alpha-KTx16, purified from
the venom of the Chinese scorpion Buthus martensi Karsch. In solution, BmTx3B
assumes a typical CSalphabeta motif, with an alpha-helix connected to a
triple-stranded beta-sheet by 3 disulfide bridges, which belongs to the first
structural group of short-chain scorpion toxins. On the other hand, BmTx3B is
quite different from other toxins (such as ChTx and AgTx2) of this group in
terms of the electrostatic and hydrophobic surface distribution. The functional
surface (beta-face) of the molecule is characterized by less basic residues
(only 2: Lys28 and Arg35) and extra aromatic residues (Phe1, Phe9, Trp15, and
Tyr37). The peptide shows a great preference for the Kca1.1 channel over the Kv
channel (about a 10(3)-fold difference). The model of BmTx3B/Kca1.1 channel
complex generated by docking and dynamic simulation reveals that the stable
binding between the BmTx3B and Kca1.1 channel is favored by a number of aromatic
pi-pi stacking interactions. The influences of these structural features on the
kinetic behavior of the toxin binding to Kca1.1 channel are also discussed.
|
|
|
|
|
|
|
|
Figure 3.
Figure 3. Stereoview for backbone superimposition of the best
25 structures of BmTx3B; each fifth residue is numbered.
|
|
Figure 5.
Figure 5. (a) The front view of the BmTx3B-Kca1.1 channel
complex generated by MOLMOL. The residues, Lys28 and Arg35,
which have formed hydrogen bonds with the residues of the
channel, are marked. (b) The top view of the BmTx3B-Kca1.1
channel complex generated by the program WebLab ViewerPro 4.0.
The Kca1.1 channel is represented as a molecular surface colored
by electrostatic potential, and BmTx3B as a green tube
structure. (c and d) Interaction interfaces of BmTx3B with
Kca1.1. (right) and Kv1.3 (left). The key interactions pairs are
indicated with black lines, while, for clarity, the interactions
between Lys28 of BmTx3B and Tyr290 (I-IV) of the Kca1.1 channel
and Tyr395 (I-IV) of the Kv1.3 channel are not shown. Blue,
yellow, green, white, and gray surfaces represent basic,
sulfur-containing, polar, nonpolar, and aromatic residues,
respectively. The red quadrate lines highlight the peptide
residues involved in  -
or
hydrophobic core interactions. (e) Aromatic clusters in the
complex of BmTx3B (blue) and Kca1.1 channel (green). The
residues predicted to form the -
stacking
clusters are shown as red line models.
|
|
|
|
|
|
The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2005,
58,
489-497)
copyright 2005.
|
|
|
|
|
|
|
