kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity.

Kellathur N. Srinivasan, Vaithiyalingam Sivaraja, Isabelle Huys, Toru Sasaki, Betty Cheng, Thallampuranam Krishnaswamy S. Kumar, Kazuki Sato, Jan Tytgat, Chin Yu, B. Chia Cheng San, Shoba Ranganathan, H. John Bowie, R. Manjunatha Kini, Ponnampalam Gopalakrishnakone

Research output: Contribution to journalArticleResearchpeer-review

Abstract

An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, kappa-hefutoxin1 and kappa-hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that kappa-hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any beta-sheets. Based on the presence of the functional diad (Tyr(5)/Lys(19)) at a distance (6.0 +/- 1.0 A) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. kappa-Hefutoxin 1 not only blocks the voltage-gated K(+)-channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of kappa-hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.

LanguageEnglish
Pages30040-30047
Number of pages8
JournalJournal of Biological Chemistry
Volume277
Issue number33
Publication statusPublished - 16 Aug 2002
Externally publishedYes

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Scorpions
Potassium Channels
Nuclear magnetic resonance
Scorpion Venoms
Voltage-Gated Potassium Channels
Disulfides
Alanine
Purification
Chemical activation
Kinetics
Proteins

Cite this

Srinivasan, K. N., Sivaraja, V., Huys, I., Sasaki, T., Cheng, B., Kumar, T. K. S., ... Gopalakrishnakone, P. (2002). kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity. Journal of Biological Chemistry, 277(33), 30040-30047.
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 ; Ranganathan, Shoba ; Bowie, H. John ; Kini, R. Manjunatha ; Gopalakrishnakone, Ponnampalam. / kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity. In: Journal of Biological Chemistry. 2002 ; Vol. 277, No. 33. pp. 30040-30047.
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title = "kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity.",
abstract = "An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, kappa-hefutoxin1 and kappa-hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that kappa-hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any beta-sheets. Based on the presence of the functional diad (Tyr(5)/Lys(19)) at a distance (6.0 +/- 1.0 A) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. kappa-Hefutoxin 1 not only blocks the voltage-gated K(+)-channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of kappa-hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.",
author = "Srinivasan, {Kellathur N.} and Vaithiyalingam Sivaraja and Isabelle Huys and Toru Sasaki and Betty Cheng and Kumar, {Thallampuranam Krishnaswamy S.} and Kazuki Sato and Jan Tytgat and Chin Yu and San, {B. Chia Cheng} and Shoba Ranganathan and Bowie, {H. John} and Kini, {R. Manjunatha} and Ponnampalam Gopalakrishnakone",
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Srinivasan, KN, Sivaraja, V, Huys, I, Sasaki, T, Cheng, B, Kumar, TKS, Sato, K, Tytgat, J, Yu, C, San, BCC, Ranganathan, S, Bowie, HJ, Kini, RM & Gopalakrishnakone, P 2002, 'kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity.', Journal of Biological Chemistry, vol. 277, no. 33, pp. 30040-30047.

kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity. / 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; Ranganathan, Shoba; Bowie, H. John; Kini, R. Manjunatha; Gopalakrishnakone, Ponnampalam.

In: Journal of Biological Chemistry, Vol. 277, No. 33, 16.08.2002, p. 30040-30047.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - kappa-Hefutoxin1, a novel toxin from the scorpion Heterometrus fulvipes with unique structure and function. Importance of the functional diad in potassium channel selectivity.

AU - Srinivasan, Kellathur N.

AU - Sivaraja, Vaithiyalingam

AU - Huys, Isabelle

AU - Sasaki, Toru

AU - Cheng, Betty

AU - Kumar, Thallampuranam Krishnaswamy S.

AU - Sato, Kazuki

AU - Tytgat, Jan

AU - Yu, Chin

AU - San, B. Chia Cheng

AU - Ranganathan, Shoba

AU - Bowie, H. John

AU - Kini, R. Manjunatha

AU - Gopalakrishnakone, Ponnampalam

PY - 2002/8/16

Y1 - 2002/8/16

N2 - An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, kappa-hefutoxin1 and kappa-hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that kappa-hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any beta-sheets. Based on the presence of the functional diad (Tyr(5)/Lys(19)) at a distance (6.0 +/- 1.0 A) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. kappa-Hefutoxin 1 not only blocks the voltage-gated K(+)-channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of kappa-hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.

AB - An important and exciting challenge in the postgenomic era is to understand the functions of newly discovered proteins based on their structures. The main thrust is to find the common structural motifs that contribute to specific functions. Using this premise, here we report the purification, solution NMR, and functional characterization of a novel class of weak potassium channel toxins from the venom of the scorpion Heterometrus fulvipes. These toxins, kappa-hefutoxin1 and kappa-hefutoxin2, exhibit no homology to any known toxins. NMR studies indicate that kappa-hefutoxin1 adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any beta-sheets. Based on the presence of the functional diad (Tyr(5)/Lys(19)) at a distance (6.0 +/- 1.0 A) comparable with other potassium channel toxins, we hypothesized its function as a potassium channel toxin. kappa-Hefutoxin 1 not only blocks the voltage-gated K(+)-channels, Kv1.3 and Kv1.2, but also slows the activation kinetics of Kv1.3 currents, a novel feature of kappa-hefutoxin 1, unlike other scorpion toxins, which are considered solely pore blockers. Alanine mutants (Y5A, K19A, and Y5A/K19A) failed to block the channels, indicating the importance of the functional diad.

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