Skip to main content
NCBI home page
Biochemical Journal logoLink to Biochemical Journal
. 2004 Mar 15;378(Pt 3):745–752. doi: 10.1042/BJ20031324

BmTx3, a scorpion toxin with two putative functional faces separately active on A-type K+ and HERG currents.

Isabelle Huys 1, Chen-Qi Xu 1, Cheng-Zhong Wang 1, Hélène Vacher 1, Marie-France Martin-Eauclaire 1, Cheng-Wu Chi 1, Jan Tytgat 1
PMCID: PMC1223995  PMID: 14599291

Abstract

A novel HERG channel blocker was isolated from the venom of the scorpion Buthus martensi Karsch, sequenced and characterized at the pharmacological level after chemical synthesis. According to the determined amino acid sequence, the cDNA and genomic genes were then cloned. The genomic gene consists of two exons interrupted by an intron of 65 bp at position -6 upstream from the mature toxin. The protein sequence of this toxin was completely identical with that of a known A-type K+ current blocker BmTx3, belonging to scorpion alpha-KTx subfamily 15. Thus BmTx3 is the first reported alpha-KTx peptide also showing HERG-blocking activity, like gamma-KTx peptides. Moreover, different from classical alpha-KTx peptides, such as charybdotoxin, BmTx3 cannot block Shaker -type K+ channels. Phylogenetic tree analysis reveals that this toxin takes an intermediate position between classical alpha-KTx and gamma-KTx toxins. From a structural point of view, we propose that two separate functional faces might exist on the BmTx3 molecule, responsible for the two different K+-current-blocking functions. Face A, composed of Arg18 and Lys19 in the alpha-helix side, might correspond to HERG blocking activity, whereas Face B, containing a putative functional dyad (Lys27 and Tyr36) in the beta-sheet side, might correspond to A-type blocking activity. A specific deletion mutant with the disrupted Face B, BmTx3-Y36P37del, loses the A-type current-blocking activity, but keeps a similar HERG-blocking activity, as seen with the wild-type toxin.

Full Text

The Full Text of this article is available as a PDF (242.3 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Cartier G. E., Yoshikami D., Gray W. R., Luo S., Olivera B. M., McIntosh J. M. A new alpha-conotoxin which targets alpha3beta2 nicotinic acetylcholine receptors. J Biol Chem. 1996 Mar 29;271(13):7522–7528. doi: 10.1074/jbc.271.13.7522. [DOI] [PubMed] [Google Scholar]
  2. Corona Miguel, Gurrola Georgina B., Merino Enrique, Cassulini Rita Restano, Valdez-Cruz Norma A., García Blanca, Ramírez-Domínguez Martha E., Coronas Fredy I. V., Zamudio Fernando Z., Wanke Enzo. A large number of novel Ergtoxin-like genes and ERG K+-channels blocking peptides from scorpions of the genus Centruroides. FEBS Lett. 2002 Dec 4;532(1-2):121–126. doi: 10.1016/s0014-5793(02)03652-9. [DOI] [PubMed] [Google Scholar]
  3. Csank C., Taylor F. M., Martindale D. W. Nuclear pre-mRNA introns: analysis and comparison of intron sequences from Tetrahymena thermophila and other eukaryotes. Nucleic Acids Res. 1990 Sep 11;18(17):5133–5141. doi: 10.1093/nar/18.17.5133. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Curran M. E., Splawski I., Timothy K. W., Vincent G. M., Green E. D., Keating M. T. A molecular basis for cardiac arrhythmia: HERG mutations cause long QT syndrome. Cell. 1995 Mar 10;80(5):795–803. doi: 10.1016/0092-8674(95)90358-5. [DOI] [PubMed] [Google Scholar]
  5. Dai L., Wu J. J., Gu Y. H., Lan Z. D., Ling M. H., Chi C. W. Genomic organization of three novel toxins from the scorpion Buthus martensi Karsch that are active on potassium channels. Biochem J. 2000 Mar 15;346(Pt 3):805–809. [PMC free article] [PubMed] [Google Scholar]
  6. Dauplais M., Lecoq A., Song J., Cotton J., Jamin N., Gilquin B., Roumestand C., Vita C., de Medeiros C. L., Rowan E. G. On the convergent evolution of animal toxins. Conservation of a diad of functional residues in potassium channel-blocking toxins with unrelated structures. J Biol Chem. 1997 Feb 14;272(7):4302–4309. doi: 10.1074/jbc.272.7.4302. [DOI] [PubMed] [Google Scholar]
  7. Delabre M. L., Pasero P., Marilley M., Bougis P. E. Promoter structure and intron-exon organization of a scorpion alpha-toxin gene. Biochemistry. 1995 May 23;34(20):6729–6736. doi: 10.1021/bi00020a018. [DOI] [PubMed] [Google Scholar]
  8. Ellis K. C., Tenenholz T. C., Jerng H., Hayhurst M., Dudlak C. S., Gilly W. F., Blaustein M. P., Weber D. J. Interaction of a toxin from the scorpion Tityus serrulatus with a cloned K+ channel from squid (sqKv1A). Biochemistry. 2001 May 22;40(20):5942–5953. doi: 10.1021/bi010173g. [DOI] [PubMed] [Google Scholar]
  9. Goldstein S. A., Pheasant D. J., Miller C. The charybdotoxin receptor of a Shaker K+ channel: peptide and channel residues mediating molecular recognition. Neuron. 1994 Jun;12(6):1377–1388. doi: 10.1016/0896-6273(94)90452-9. [DOI] [PubMed] [Google Scholar]
  10. Goudet Cyril, Chi Cheng-Wu, Tytgat Jan. An overview of toxins and genes from the venom of the Asian scorpion Buthus martensi Karsch. Toxicon. 2002 Sep;40(9):1239–1258. doi: 10.1016/s0041-0101(02)00142-3. [DOI] [PubMed] [Google Scholar]
  11. Gurevitz M., Gordon D., Ben-Natan S., Turkov M., Froy O. Diversification of neurotoxins by C-tail 'wiggling': a scorpion recipe for survival. FASEB J. 2001 May;15(7):1201–1205. doi: 10.1096/fj.00-0571hyp. [DOI] [PubMed] [Google Scholar]
  12. Huys Isabelle, Dyason Karin, Waelkens Etienne, Verdonck Fons, van Zyl Johann, du Plessis Johan, Müller Gert J., van der Walt Jurg, Clynen Elke, Schoofs Liliane. Purification, characterization and biosynthesis of parabutoxin 3, a component of Parabuthus transvaalicus venom. Eur J Biochem. 2002 Apr;269(7):1854–1865. doi: 10.1046/j.1432-1033.2002.02833.x. [DOI] [PubMed] [Google Scholar]
  13. Korolkova Yuliya V., Bocharov Eduard V., Angelo Kamilla, Maslennikov Innokenty V., Grinenko Olga V., Lipkin Aleksey V., Nosyreva Elena D., Pluzhnikov Kirill A., Olesen Soren-Peter, Arseniev Alexander S. New binding site on common molecular scaffold provides HERG channel specificity of scorpion toxin BeKm-1. J Biol Chem. 2002 Jul 31;277(45):43104–43109. doi: 10.1074/jbc.M204083200. [DOI] [PubMed] [Google Scholar]
  14. Kumar S., Tamura K., Jakobsen I. B., Nei M. MEGA2: molecular evolutionary genetics analysis software. Bioinformatics. 2001 Dec;17(12):1244–1245. doi: 10.1093/bioinformatics/17.12.1244. [DOI] [PubMed] [Google Scholar]
  15. Legros C., Bougis P. E., Martin-Eauclaire M. F. Genomic organization of the KTX2 gene, encoding a 'short' scorpion toxin active on K+ channels. FEBS Lett. 1997 Jan 27;402(1):45–49. doi: 10.1016/s0014-5793(96)01492-5. [DOI] [PubMed] [Google Scholar]
  16. Legros Christian, Bougis Pierre E., Martin-Eauclaire Marie-France. Characterisation of the genes encoding Aa1 isoforms from the scorpion Androctonus australis. Toxicon. 2003 Jan;41(1):115–119. doi: 10.1016/s0041-0101(02)00212-x. [DOI] [PubMed] [Google Scholar]
  17. Pardo-Lopez Liliana, Zhang Mei, Liu Jie, Jiang Min, Possani Lourival D., Tseng Gea-Ny. Mapping the binding site of a human ether-a-go-go-related gene-specific peptide toxin (ErgTx) to the channel's outer vestibule. J Biol Chem. 2002 Feb 25;277(19):16403–16411. doi: 10.1074/jbc.M200460200. [DOI] [PubMed] [Google Scholar]
  18. Park C. S., Hausdorff S. F., Miller C. Design, synthesis, and functional expression of a gene for charybdotoxin, a peptide blocker of K+ channels. Proc Natl Acad Sci U S A. 1991 Mar 15;88(6):2046–2050. doi: 10.1073/pnas.88.6.2046. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Peitsch M. C., Schwede T., Guex N. Automated protein modelling--the proteome in 3D. Pharmacogenomics. 2000 Aug;1(3):257–266. doi: 10.1517/14622416.1.3.257. [DOI] [PubMed] [Google Scholar]
  20. Pisciotta M., Coronas F. I., Possani L. D., Prestipino G. The Androctonus australis garzoni scorpion venom contains toxins that selectively affect voltage-dependent K(+)-channels in cerebellum granular cells. Eur Biophys J. 1998;27(1):69–73. doi: 10.1007/s002490050112. [DOI] [PubMed] [Google Scholar]
  21. Rauer H., Lanigan M. D., Pennington M. W., Aiyar J., Ghanshani S., Cahalan M. D., Norton R. S., Chandy K. G. Structure-guided transformation of charybdotoxin yields an analog that selectively targets Ca(2+)-activated over voltage-gated K(+) channels. J Biol Chem. 2000 Jan 14;275(2):1201–1208. doi: 10.1074/jbc.275.2.1201. [DOI] [PubMed] [Google Scholar]
  22. Rodríguez de la Vega Ricardo C., Merino Enrique, Becerril Baltazar, Possani Lourival D. Novel interactions between K+ channels and scorpion toxins. Trends Pharmacol Sci. 2003 May;24(5):222–227. doi: 10.1016/S0165-6147(03)00080-4. [DOI] [PubMed] [Google Scholar]
  23. Romi-Lebrun R., Lebrun B., Martin-Eauclaire M. F., Ishiguro M., Escoubas P., Wu F. Q., Hisada M., Pongs O., Nakajima T. Purification, characterization, and synthesis of three novel toxins from the Chinese scorpion Buthus martensi, which act on K+ channels. Biochemistry. 1997 Nov 4;36(44):13473–13482. doi: 10.1021/bi971044w. [DOI] [PubMed] [Google Scholar]
  24. Sanguinetti M. C., Jiang C., Curran M. E., Keating M. T. A mechanistic link between an inherited and an acquired cardiac arrhythmia: HERG encodes the IKr potassium channel. Cell. 1995 Apr 21;81(2):299–307. doi: 10.1016/0092-8674(95)90340-2. [DOI] [PubMed] [Google Scholar]
  25. Srinivasan Kellathur N., Sivaraja Vaithiyalingam, Huys Isabelle, Sasaki Toru, Cheng Betty, Kumar Thallampuranam Krishnaswamy S., Sato Kazuki, Tytgat Jan, Yu Chin, San B. Chia Cheng. kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity. J Biol Chem. 2002 May 28;277(33):30040–30047. doi: 10.1074/jbc.M111258200. [DOI] [PubMed] [Google Scholar]
  26. Thompson J. D., Gibson T. J., Plewniak F., Jeanmougin F., Higgins D. G. The CLUSTAL_X windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res. 1997 Dec 15;25(24):4876–4882. doi: 10.1093/nar/25.24.4876. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Tytgat J., Buyse G., Eggermont J., Droogmans G., Nilius B., Daenens P. Do voltage-gated Kv1.1 and inward rectifier Kir2.1 potassium channels form heteromultimers? FEBS Lett. 1996 Jul 29;390(3):280–284. doi: 10.1016/0014-5793(96)00674-6. [DOI] [PubMed] [Google Scholar]
  28. Tytgat J., Chandy K. G., Garcia M. L., Gutman G. A., Martin-Eauclaire M. F., van der Walt J. J., Possani L. D. A unified nomenclature for short-chain peptides isolated from scorpion venoms: alpha-KTx molecular subfamilies. Trends Pharmacol Sci. 1999 Nov;20(11):444–447. doi: 10.1016/s0165-6147(99)01398-x. [DOI] [PubMed] [Google Scholar]
  29. Vacher H., Romi-Lebrun R., Mourre C., Lebrun B., Kourrich S., Masméjean F., Nakajima T., Legros C., Crest M., Bougis P. E. A new class of scorpion toxin binding sites related to an A-type K+ channel: pharmacological characterization and localization in rat brain. FEBS Lett. 2001 Jul 13;501(1):31–36. doi: 10.1016/s0014-5793(01)02620-5. [DOI] [PubMed] [Google Scholar]
  30. Vacher Hélène, Alami Meriem, Crest Marcel, Possani Lourival D., Bougis Pierre E., Martin-Eauclaire Marie-France. Expanding the scorpion toxin alpha-KTX 15 family with AmmTX3 from Androctonus mauretanicus. Eur J Biochem. 2002 Dec;269(24):6037–6041. doi: 10.1046/j.1432-1033.2002.03294.x. [DOI] [PubMed] [Google Scholar]
  31. Vacher Hélène, Romi-Lebrun Régine, Crest Marcel, Masmejean Frédérique, Bougis Pierre E., Darbon Hervé, Martin-Eauclaire Marie-France. Functional consequences of deleting the two C-terminal residues of the scorpion toxin BmTX3. Biochim Biophys Acta. 2003 Mar 21;1646(1-2):152–156. doi: 10.1016/s1570-9639(02)00557-5. [DOI] [PubMed] [Google Scholar]
  32. Wang Chun-Guang, Gilles Nicolas, Hamon Alain, Le Gall Frédéric, Stankiewicz Maria, Pelhate Marcel, Xiong Yu-Mei, Wang Da-Cheng, Chi Cheng-Wu. Exploration of the functional site of a scorpion alpha-like toxin by site-directed mutagenesis. Biochemistry. 2003 Apr 29;42(16):4699–4708. doi: 10.1021/bi0270438. [DOI] [PubMed] [Google Scholar]
  33. Warmke J. W., Ganetzky B. A family of potassium channel genes related to eag in Drosophila and mammals. Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):3438–3442. doi: 10.1073/pnas.91.8.3438. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Wickenden Alan. K(+) channels as therapeutic drug targets. Pharmacol Ther. 2002 Apr-May;94(1-2):157–182. doi: 10.1016/s0163-7258(02)00201-2. [DOI] [PubMed] [Google Scholar]
  35. Wu J. J., Dai L., Lan Z. D., Chi C. W. Genomic organization of three neurotoxins active on small conductance Ca2+-activated potassium channels from the scorpion Buthus martensi Karsch. FEBS Lett. 1999 Jun 11;452(3):360–364. doi: 10.1016/s0014-5793(99)00651-1. [DOI] [PubMed] [Google Scholar]
  36. Wu J. J., Dai L., Lan Z. D., Chi C. W. The gene cloning and sequencing of Bm-12, a chlorotoxin-like peptide from the scorpion Buthus martensi Karsch. Toxicon. 2000 May;38(5):661–668. doi: 10.1016/s0041-0101(99)00181-6. [DOI] [PubMed] [Google Scholar]
  37. Xu Chen-Qi, Zhu Shun-Yi, Chi Cheng-Wu, Tytgat Jan. Turret and pore block of K+ channels: what is the difference? Trends Pharmacol Sci. 2003 Sep;24(9):446–449. doi: 10.1016/S0165-6147(03)00223-2. [DOI] [PubMed] [Google Scholar]
  38. Zhang Mei, Korolkova Yuliya V., Liu Jie, Jiang Min, Grishin Eugene V., Tseng Gea-Ny. BeKm-1 is a HERG-specific toxin that shares the structure with ChTx but the mechanism of action with ErgTx1. Biophys J. 2003 May;84(5):3022–3036. doi: 10.1016/S0006-3495(03)70028-9. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Biochemical Journal are provided here courtesy of The Biochemical Society

RESOURCES