The Architecture of Selectivity: Molecular Basis of BlTx2 Discrimination Among Kv Channels and Kv4 Isoforms.
- 1Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel.
- 2The Zelman Center for Brain Science Research, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 8410501, Israel.
Abstract
Kv4 channels generate transient A-type potassium currents, but the contribution of Kv4.1 remains difficult to define because few pharmacological tools discriminate among Kv4 isoforms. We investigated the molecular basis of Kv4.1-selective inhibition by BlTx2, an α-KTx15 scorpion toxin from Buthacus leptochelys. Using electrophysiology, mutagenesis, tandem-channel analysis, structural modeling, and evolutionary analysis, we mapped the determinants governing BlTx2 activity and selectivity. Substitution of conserved α-KTx residues Lys27 and Tyr36 abolished detectable inhibition, whereas N30A reduced potency, supporting a canonical pore-blocking mechanism. A Kv4.1/Kv4.3 tandem chimera reduced BlTx2 potency, consistent with a contribution of adjacent Kv4.1 subunits to the high-affinity toxin-binding surface. Channel mutagenesis identified the Kv4.2/Kv4.3 lysine corresponding to Kv4.1 Asn355 as a key barrier to BlTx2 activity, since introducing this lysine into Kv4.1 abolished detectable inhibition. Mutational mapping of BlTx2 revealed that pore-facing residues required for inhibition are separated from peripheral residues that tune potency and cross-reactivity. In particular, Q9K and I18K conferred Kv1.2 activity, partly through interaction with Kv1.2 Glu355. Evolutionary analysis linked conserved pore-facing residues to purifying selection, and peripheral determinants to diversification. These findings identify distinct conserved and peripheral determinants that together shape BlTx2 activity and selectivity, thereby establishing BlTx2 as a useful probe for Kv4.1 function.
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BibTeX
@article{levy2026architecture,
title = {{The Architecture of Selectivity: Molecular Basis of BlTx2 Discrimination Among Kv Channels and Kv4 Isoforms.}},
author = {Yuval Levy and Ayalon Reis and Galit Blecher and Oksana Daron and Sara Dadon and Raz Zarivach and Noam Zilberberg},
journal = {Toxins},
year = {2026},
month = oct,
doi = {10.3390/toxins18100431},
url = {https://europepmc.org/article/MED/42931522},
note = {CC BY},
}
RIS
TY - JOUR
TI - The Architecture of Selectivity: Molecular Basis of BlTx2 Discrimination Among Kv Channels and Kv4 Isoforms.
AU - Yuval Levy
AU - Ayalon Reis
AU - Galit Blecher
AU - Oksana Daron
AU - Sara Dadon
AU - Raz Zarivach
AU - Noam Zilberberg
PY - 2026
DA - 2026/10/08
JO - Toxins
DO - 10.3390/toxins18100431
UR - https://europepmc.org/article/MED/42931522
AB - Kv4 channels generate transient A-type potassium currents, but the contribution of Kv4.1 remains difficult to define because few pharmacological tools discriminate among Kv4 isoforms. We investigated the molecular basis of Kv4.1-selective inhibition by BlTx2, an α-KTx15 scorpion toxin from Buthacus leptochelys. Using electrophysiology, mutagenesis, tandem-channel analysis, structural modeling, and evolutionary analysis, we mapped the determinants governing BlTx2 activity and selectivity. Substitution of conserved α-KTx residues Lys27 and Tyr36 abolished detectable inhibition, whereas N30A reduced potency, supporting a canonical pore-blocking mechanism. A Kv4.1/Kv4.3 tandem chimera reduced BlTx2 potency, consistent with a contribution of adjacent Kv4.1 subunits to the high-affinity toxin-binding surface. Channel mutagenesis identified the Kv4.2/Kv4.3 lysine corresponding to Kv4.1 Asn355 as a key barrier to BlTx2 activity, since introducing this lysine into Kv4.1 abolished detectable inhibition. Mutational mapping of BlTx2 revealed that pore-facing residues required for inhibition are separated from peripheral residues that tune potency and cross-reactivity. In particular, Q9K and I18K conferred Kv1.2 activity, partly through interaction with Kv1.2 Glu355. Evolutionary analysis linked conserved pore-facing residues to purifying selection, and peripheral determinants to diversification. These findings identify distinct conserved and peripheral determinants that together shape BlTx2 activity and selectivity, thereby establishing BlTx2 as a useful probe for Kv4.1 function.
SN - 2072-6651
ER -