Molecular diversity of peptides from Pandercetes sp. spider venom and antagonistic activity on voltage-gated calcium channels of the κ-LhTx-1 toxin.

The venom of toxic animals represents a rich reservoir of bioactive peptides, which serve as invaluable tools for ion channel research, drug and insecticide development. While venoms of various species have been extensively studied, the venom composition of spiders from the Pandercetes genus remains largely unexplored. In this study, the peptide diversity of spider Pandercetes sp. was explored by constructing a venom cDNA library. A total of 626 high-quality expression sequence tags (ESTs) were obtained, categorized into toxin-like ESTs, cellular component ESTs, and non-classified ESTs. From the toxin-like ESTs, 102 non-redundant toxin-like peptides were identified and grouped into 11 families according to sequence homology and cysteine framework. Bioinformatic analysis revealed these peptide toxins share moderate similarity with those identified in the venoms of Heteropoda pingtungensis and Heteropoda venatoria. Mass spectrometric analysis identified 154 peptides with molecular masses ranging from 1000 to 8000 Da, underscoring the diverse and intricate nature of the venom. However, the biological functions of the major toxins remain largely unknown. To address this, venom fractions obtained by reverse-phase high-performance liquid chromatography (RP-HPLC) were assessed for inhibition of voltage-gated calcium channel currents using patch-clamp electrophysiology. Notably, κ-LhTx-1, a highly abundant peptide, was previously identified as a selective inhibitor of mammalian Kv4 channels, and also exhibits inhibitory activity against L-type Cav channels, reflecting its multi-target role. In conclusion, this study provides a novel insight into the molecular diversity in the venoms of spider Pandercetes sp. and lays a foundation for the discovery of active molecules.