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Characterization of Kbot21 Reveals Novel Side Chain Interactions of Scorpion Toxins Inhibiting Voltage-Gated Potassium Channels.

ElFessi-Magouri R, Peigneur S, Othman H, Srairi-Abid N, ElAyeb M, Tytgat J, Kharrat R - PLoS ONE (2015)

Bottom Line: Scorpion toxins are important pharmacological tools for probing the physiological roles of ion channels which are involved in many physiological processes and as such have significant therapeutic potential.Kbot21 targets KV channel subtypes whereas BmBKTx1 is active on both big conductance (BK) and small conductance (SK) Ca2+-activated K+ channel subtypes, but has no effects on Kv channel subtypes.The docking model of Kbot21 with the Kv1.2 channel shows that the D24 and R13 side-chain of Kbot21 are critical for its interaction with KV channels.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis,13 Place Pasteur, BP-74, 1002, Tunis, Tunisie.

ABSTRACT
Scorpion toxins are important pharmacological tools for probing the physiological roles of ion channels which are involved in many physiological processes and as such have significant therapeutic potential. The discovery of new scorpion toxins with different specificities and affinities is needed to further characterize the physiology of ion channels. In this regard, a new short polypeptide called Kbot21 has been purified to homogeneity from the venom of Buthus occitanus tunetanus scorpion. Kbot21 is structurally related to BmBKTx1 from the venom of the Asian scorpion Buthus martensii Karsch. These two toxins differ by only two residues at position 13 (R /V) and 24 (D/N).Despite their very similar sequences, Kbot21 and BmBKTx1 differ in their electrophysiological activities. Kbot21 targets KV channel subtypes whereas BmBKTx1 is active on both big conductance (BK) and small conductance (SK) Ca2+-activated K+ channel subtypes, but has no effects on Kv channel subtypes. The docking model of Kbot21 with the Kv1.2 channel shows that the D24 and R13 side-chain of Kbot21 are critical for its interaction with KV channels.

No MeSH data available.


Related in: MedlinePlus

Purification of Kbot21 from scorpion Buthus occitanus tunetanus venom.(A) Chromatography of fraction BotG50 on semi preparative C8 reverse phase HPLC column. (B) Chromatography of fraction B1on C18-RP-HPLC, B’1 was collected at 29min. (C) Kbot21 was purified from the fraction B’1 by C18-RP-HPLC. It is collected at 21min.
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pone.0137611.g001: Purification of Kbot21 from scorpion Buthus occitanus tunetanus venom.(A) Chromatography of fraction BotG50 on semi preparative C8 reverse phase HPLC column. (B) Chromatography of fraction B1on C18-RP-HPLC, B’1 was collected at 29min. (C) Kbot21 was purified from the fraction B’1 by C18-RP-HPLC. It is collected at 21min.

Mentions: The toxic fraction obtained from Sephadex G-50 chromatography of the Buthus occitanus tunetanus scorpion venom was fractionated by a C8 semi preparative reversed-phase HPLC (Fig 1A). Fraction B1 containing peptides in the range of 3.7–4.6 KDa, according to SDS-PAGE, were collected, lyophilised and loaded on to an analytical C18 reverse-phase HPLC column (Beckman Fullerton) using a linear gradient (12% to 35% in 70 min). The fraction B’1 was composed of three fractions when eluted by more resolutive gradient (12 to 30% in 30 min) (Fig 1B). The most representative fraction shows only one band at about 4 kDa on SDS-PAGE electrophoresis and a single component with molecular weight of Da by mass spectrometry obtained by MALDI is nearly identical with the average theoretical molecular mass calculated for the fully oxidized form of Kbot21 (Da) (data not shown). This molecule, named Kbot21 (Fig 1C).


Characterization of Kbot21 Reveals Novel Side Chain Interactions of Scorpion Toxins Inhibiting Voltage-Gated Potassium Channels.

ElFessi-Magouri R, Peigneur S, Othman H, Srairi-Abid N, ElAyeb M, Tytgat J, Kharrat R - PLoS ONE (2015)

Purification of Kbot21 from scorpion Buthus occitanus tunetanus venom.(A) Chromatography of fraction BotG50 on semi preparative C8 reverse phase HPLC column. (B) Chromatography of fraction B1on C18-RP-HPLC, B’1 was collected at 29min. (C) Kbot21 was purified from the fraction B’1 by C18-RP-HPLC. It is collected at 21min.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4580410&req=5

pone.0137611.g001: Purification of Kbot21 from scorpion Buthus occitanus tunetanus venom.(A) Chromatography of fraction BotG50 on semi preparative C8 reverse phase HPLC column. (B) Chromatography of fraction B1on C18-RP-HPLC, B’1 was collected at 29min. (C) Kbot21 was purified from the fraction B’1 by C18-RP-HPLC. It is collected at 21min.
Mentions: The toxic fraction obtained from Sephadex G-50 chromatography of the Buthus occitanus tunetanus scorpion venom was fractionated by a C8 semi preparative reversed-phase HPLC (Fig 1A). Fraction B1 containing peptides in the range of 3.7–4.6 KDa, according to SDS-PAGE, were collected, lyophilised and loaded on to an analytical C18 reverse-phase HPLC column (Beckman Fullerton) using a linear gradient (12% to 35% in 70 min). The fraction B’1 was composed of three fractions when eluted by more resolutive gradient (12 to 30% in 30 min) (Fig 1B). The most representative fraction shows only one band at about 4 kDa on SDS-PAGE electrophoresis and a single component with molecular weight of Da by mass spectrometry obtained by MALDI is nearly identical with the average theoretical molecular mass calculated for the fully oxidized form of Kbot21 (Da) (data not shown). This molecule, named Kbot21 (Fig 1C).

Bottom Line: Scorpion toxins are important pharmacological tools for probing the physiological roles of ion channels which are involved in many physiological processes and as such have significant therapeutic potential.Kbot21 targets KV channel subtypes whereas BmBKTx1 is active on both big conductance (BK) and small conductance (SK) Ca2+-activated K+ channel subtypes, but has no effects on Kv channel subtypes.The docking model of Kbot21 with the Kv1.2 channel shows that the D24 and R13 side-chain of Kbot21 are critical for its interaction with KV channels.

View Article: PubMed Central - PubMed

Affiliation: Laboratoire des Venins et Molécules Thérapeutiques, Institut Pasteur de Tunis,13 Place Pasteur, BP-74, 1002, Tunis, Tunisie.

ABSTRACT
Scorpion toxins are important pharmacological tools for probing the physiological roles of ion channels which are involved in many physiological processes and as such have significant therapeutic potential. The discovery of new scorpion toxins with different specificities and affinities is needed to further characterize the physiology of ion channels. In this regard, a new short polypeptide called Kbot21 has been purified to homogeneity from the venom of Buthus occitanus tunetanus scorpion. Kbot21 is structurally related to BmBKTx1 from the venom of the Asian scorpion Buthus martensii Karsch. These two toxins differ by only two residues at position 13 (R /V) and 24 (D/N).Despite their very similar sequences, Kbot21 and BmBKTx1 differ in their electrophysiological activities. Kbot21 targets KV channel subtypes whereas BmBKTx1 is active on both big conductance (BK) and small conductance (SK) Ca2+-activated K+ channel subtypes, but has no effects on Kv channel subtypes. The docking model of Kbot21 with the Kv1.2 channel shows that the D24 and R13 side-chain of Kbot21 are critical for its interaction with KV channels.

No MeSH data available.


Related in: MedlinePlus