Exploring structural features of the interaction between the scorpion toxinCnErg1 and ERG K+ channels.

Karine Frénal (1) , Chen-Qi Xu (2, 3) , Nicolas Wolff (1) , Karine Wecker (1) , Georgina B. Gurrola (4) , Shun-Yi Zhu (2) , Cheng-Wu Chi (3, 5) , Lourival D. Possani (4) , Jan Tytgat (2) , Muriel Delepierre (1)

1 Résonance Magnétique Nucléaire des Biomolécules
2 Laboratory of Toxicology
3 Key laboratory of Proteomics
4 Institute of Biotechnology
5 Institute of Protein Research

The gamma-KTx-type scorpion toxins specific for K+ channels were found to interact with ERG channels on the turret region, while alpha-KTx3.2 Agitoxin-2 binds to the pore region of the Shaker K+ channel, and alpha-KTx5.3 BmP05 binds to the intermediate region of the small-conductance calcium-activated K-channel (SK(Ca)). In order to explore the critical residues for gamma-KTx binding, we determined the NMR structure of native gamma-KTx1.1 (CnErg1), a 42 amino acid residues scorpion toxin isolated from the venom of the Mexican scorpion Centruro?s noxius Hoffmann, and we used computational evolutionary trace (ET) analysis to predict possible structural and functional features of interacting surfaces. The 1H-NMR three-dimensional solution structure of native ergtoxin (CnErg1) was solved using a total of 452 distance constraints, 13 3J(NH-Halpha) and 10 hydrogen bonds. The structure is characterized by 2 segments of alpha-helices and a triple-stranded antiparallel beta-sheet stabilized by 4 disulfide bridges. The ET and structural analysis provided indication of the presence of two important amino acid residue clusters, one hydrophobic and the other hydrophilic, that should be involved in the surface contact between the toxin and the channel. Some features of the proposed interacting surface are discussed.

Domaines: Biologie structurale [q-bio.BM]

Karine Frénal, Chen-Qi Xu, Nicolas Wolff, Karine Wecker, Georgina B. Gurrola, et al.. Exploring structural features of the interaction between the scorpion toxinCnErg1 and ERG K+ channels.. Proteins - Structure, Function and Bioinformatics, 2004, 56 (2), pp.367-75. ⟨10.1002/prot.20102⟩. ⟨pasteur-00369565⟩