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Evidence for a function‐specific mutation in the neurotoxin, parabutoxin 3
Author(s) -
Huys Isabelle,
Tytgat Jan
Publication year - 2003
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.2003.02613.x
Subject(s) - xenopus , neurotoxin , mutant , scorpion toxin , chemistry , protein subunit , amino acid , biophysics , biochemistry , stereochemistry , biology , venom , gene , scorpion
Parabutoxin 3 (PBTx3), a short‐chain α‐K + neurotoxin from the scorpion, Parabuthus transvaalicus , is a 37‐residue polypeptide cross‐linked by three disulphide bridges. The affinity towards Kv1 channels is very weak ( K d ≈ 79 µ m for Kv1.1 channels), or moderate ( K d ≈ 500 n m for Kv1.2 and Kv1.3 channels). In an effort to generate a more potent K + channel blocker, we recombinantly produced a mutant PBTx3 by the introduction of an aromatic amino acid, fenylalanine in close proximity of the crucial lysine 26 residue, to create a functional diad similar to subfamily three α‐K + toxins. The mutant was tested for his ability to block Kv1.1, Kv1.2 and Kv1.3 channels in Xenopus laevis oocytes: a hundred‐fold higher affinity towards Kv1.1 channels and a fivefold increase in affinity towards Kv1.3 channels was observed, when compared to the wild‐type toxin. The effect on Kv1.2 channels was similar to the wild‐type toxin, indicating a specific interaction site for the mutated residue onto the different Kv‐type channels.