HGETX1, THE FIRST K+-CHANNEL SPECIFIC TOXIN CHARACTERIZED FROM THE VENOM OF THE SCORPION Hadrurus gertschi *

SCHWARTZ E.F. (1, 3), SCHWARTZ C. A. (1), GÓMEZ-LAGUNAS F. (2), ZAMUDIO F. Z. (3), POSSANI L. D. (3)

(1) Department of Physiological Sciences, Institute of Biological Sciences, University of Brasilia, Brasilia, DF, 70910-900, Brazil; (2) Department of Physiology, School of Medicine, National Autonomous University of Mexico, Ciudad Universitaria, Mexico City, DF, 04510, Mexico; (3) Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Cuernavaca, Morelos, 62210, Mexico

A novel K+-channel toxin was identified, purified and characterized from the venom of the scorpion Hadrurus gertschi (abbreviated HgeTx1). It is a 36 amino acids long peptide, has a molecular mass of 3950 atomic mass units (a.m.u.) and contains four disulfide bridges established between Cys1-Cys5, Cys2-Cys6, Cys3-Cys7 and Cys4-Cys8. HgeTx1 blocks reversibly the Shaker B K+-channels with a Kd of 52 nM. It shares 60, 45 and 40% sequence identity respectively with Heterometrus spinnifer toxin1 (HsTX1), Scorpio maurus K+-toxin (maurotoxin) and Pandinus imperator toxin1 (Pi1), all four-disulfide bridged toxins. HgeTx1 is 57-58% identical with the other scorpion K+-channel toxins that contain only three disulfide bridges. Based on sequence comparison, chain length and number of disulfide bridges analysis we classify HgeTx1 into subfamily 6 of the -KTx scorpion toxins (systematic name: -KTx 6.14).

*The complete work was published on Toxicon (2006), doi:10.1016/j.toxicon.2006.08.009

KEY WORDS: Amino acid sequence, Hadrurus gertschi, HgeTx1, K+ channel, scorpion toxin, Shaker B

FINANCIAL SUPPORT: CNPq, DPP-FUB, CONACyT, DGAPA-UNAM

CORRESPONDENCE TO: Elisabeth F. Schwartz, Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, 70910-900, Brasil, Phone: 55-61-33072160, Fax: 55-61-32741251, E.mail: efschwa@unb.br