PDBsum entry 1m2s

Toxin

PDB id: 1m2s

Contents

Protein chain

37 a.a.

PDB id:

1m2s

Name:

Toxin

Title:

Solution structure of a new potassium channels blocker from the venom of chinese scorpion buthus martensi karsch

Structure:

Toxin bmtx3. Chain: a. Synonym: neurotoxin tx3

Source:

Mesobuthus martensii. Chinese scorpion. Organism_taxid: 34649. Secretion: venom

NMR struc:

25 models

Authors:

Y.Wang,M.Li,N.Zhang,G.Wu,G.Hu,H.Wu

Key ref:

Y.Wang et al. (2005). The solution structure of BmTx3B, a member of the scorpion toxin subfamily alpha-KTx 16. Proteins, 58, 489-497. PubMed id: 15558557 DOI: 10.1002/prot.20322

Date:

25-Jun-02 Release date: 06-Apr-04

Protein chain

Q9NBG9  (KA162_MESMA) -  Potassium channel toxin alpha-KTx 16.2 from Mesobuthus martensii

Seq: 59 a.a.

Struc: 37 a.a.

DOI no: 10.1002/prot.20322

Proteins 58:489-497 (2005)

PubMed id: 15558557

The solution structure of BmTx3B, a member of the scorpion toxin subfamily alpha-KTx 16.

Y.Wang, X.Chen, N.Zhang, G.Wu, H.Wu.

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.

Selected figure(s)

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.

Figures were selected by an automated process.