Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Dec;334(Pt 1):149037.
doi: 10.1016/j.ijbiomac.2025.149037. Epub 2025 Nov 13.

Exploring the unknown activity of the Huwentoxin-II spider toxin family: A screening of Ap1 toxins from Acanthoscurria paulensis venom

Alessa Bembom Garcia  1 , Caroline Barbosa Roque Mourão  2 , Leandro Ambrósio Campos  1 , Froylán Gómez-Lagunas  3 , Steve Peigneur  4 , Kathleen Carleer  5 , Jan Tytgat  5 , Jonathan Martins do Nascimento  1 , Gabriel Avohay Alves Campos  1 , Márcia Renata Mortari  1 , Elisabeth Ferroni Schwartz  1 , Diogo Vieira Tibery  6
Affiliations

Exploring the unknown activity of the Huwentoxin-II spider toxin family: A screening of Ap1 toxins from Acanthoscurria paulensis venom

Alessa Bembom Garcia et al. Int J Biol Macromol. 2025 Dec.

Abstract

Spider venoms are complex mixtures containing neuropeptides that act on ion channels and neurotransmitter receptors. In this study, we investigated Ap1a and Ap1b, two homologous peptides isolated from the venom of the Brazilian tarantula Acanthoscurria paulensis. Ap1a, the most abundant peptide in this venom, and Ap1b, its isoform differing by a single hydrophobic residue (Ile42 → Val), were classified within the Huwentoxin-II family and exhibit structural features consistent with the inhibitor cystine knot (ICK) motif. Circular dichroism (CD) analyses confirmed their high thermal stability and similar secondary structures, mainly composed of β-sheets, β-turns, and disordered regions. Insecticidal assays demonstrated dose-dependent paralysis in Spodoptera frugiperda larvae induced by Ap1b, with an ED₅₀ (9.09 ± 1.67 μg/g) value comparable to Ap1a (13 μg/g). Electrophysiological screening showed that Ap1a modulates human voltage-gated sodium channels (hNav1.1, hNav1.3, and hNav1.7), shifting activation to more hyperpolarized voltages and reducing current amplitude. No significant effects were observed on insect Nav channels (BgNav1, VdNav1), potassium channels (Shaker, Shab, Shal, Shaw, KQT1, Kv1.1, rKv4.2, hKv7), or on glutamate binding and glutamate-gated chloride channels, suggesting potential involvement of calcium signaling pathways. Comparative phylogenetic and structural analyses positioned Ap1a and Ap1b within a monophyletic group of Theraphosinae tarantula toxins, supporting an evolutionary divergence within the Huwentoxin-II family where both DDH and ICK structural motifs coexist. This study provides the first comprehensive electrophysiological and functional characterization of an ICK-containing Huwentoxin-II peptide, advancing our understanding of spider venom neuropeptide diversity and function.

Keywords: Disulfide-rich peptides; Electrophysiology; Huwentoxin-II toxin family; ICK motif; Ion channels; Neuropeptides; Spider venom.

PubMed Disclaimer

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

LinkOut - more resources