Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1975466 | Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology | 2012 | 8 Pages |
Abstract
The α-KTx14 subfamily of scorpion toxins is a group of short-chain polypeptides affecting K+ channels, including five known members which are restrictedly distributed in Mesobuthus martensii. Here, we describe seven new α-KTx14 peptides from M. martensii and its sibling species Mesobuthus eupeus, two of which (termed MarKTX-3 and MeuKTX-1) were chemically synthesized and refolded for structural and functional studies. Electrophysiological recordings of effects of these two peptides on an array of voltage-gated potassium channels revealed that MarKTX-3 was capable of inhibiting five mammalian Kv1 isoforms (rKv1.1-rKv1.5) and the Drosophila Shaker channel with low potency whereas MeuKTX-1 lacks such activity. Circular dichroism spectroscopy analysis combined with homology modeling demonstrates that MarKTX-3 and MeuKTX-1 both adopt a similar cysteine-stabilized α-helical and β-sheet fold. Evolutionary analysis indicates accelerated amino acid substitutions in the mature-peptide-encoding regions of orthologous α-KTx14 peptides after speciation, thereby providing evidences for adaptive evolution and functional divergence of this subfamily.
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Authors
Bin Gao, Shunyi Zhu,