Isolation and characterization of a structurally unique β-hairpin venom peptide from the predatory ant Anochetus emarginatus

Axel Touchard (1) , Andreas Brust (2) , Fernanda Caldas Cardoso (2) , Yanni K.-Y. Chin (2) , Volker Herzig (2) , Ai-Hua Jin (2) , Alain Dejean (1, 3) , Paul F. Alewood (2) , Glenn F. King (2) , Jérôme Orivel (1) , Pierre Escoubas (4)

1 UMR ECOFOG - Ecologie des forêts de Guyane
2 Institut for Molecular Bioscience
3 LEFE - Laboratoire Ecologie Fonctionnelle et Environnement
4 VenomeTech

Background: Most ant venoms consist predominantly of small linear peptides, although some contain disulfide linked peptides as minor components. However, in striking contrast to other ant species, some Anochetus venoms are composed primarily of disulfide-rich peptides. In this study, we investigated the venom of the ant Anochetus emarginatus with the aim of exploring these novel disulfide-rich peptides. Methods: The venom peptidome was initially investigated using a combination of reversed-phase HPLC and mass spectrometry, then the amino acid sequences of the major peptides were determined using a combination of Edman degradation and de novo MS/MS sequencing. We focused on one of these peptides, U-1-PONTX-Ae1a (Ae1a), because of its novel sequence, which we predicted would form a novel 3D fold. Ae1a was chemically synthesized using Fmoc chemistry and its 3D structure was elucidated using NMR spectroscopy. The peptide was then tested for insecticidal activity and its effect on a range of human ion channels. Results: Seven peptides named poneritoxins (PONTXs) were isolated and sequenced. The three-dimensional structure of synthetic Ae1a revealed a novel, compact scaffold in which a C-terminal beta-hairpin is connected to the N-terminal region via two disulfide bonds. Synthetic Ae1a reversibly paralyzed blowflies and inhibited human L-type voltage-gated calcium channels (Ca(v)1). Conclusions: Poneritoxins from Anochetus emarginatus venom are a novel class of toxins that are structurally unique among animal venoms. General significance: This study demonstrates that Anochetus ant venoms are a rich source of novel ion channel modulating peptides, some of which might be useful leads for the development of biopesticides.

Mots clés: ant venom; anochetus; poneritoxins; U-1-pontx-aela; neurotoxin; disulfide-rich peptides; L-type calcium channels

Domaines: Sciences du Vivant [q-bio]

Axel Touchard, Andreas Brust, Fernanda Caldas Cardoso, Yanni K.-Y. Chin, Volker Herzig, et al.. Isolation and characterization of a structurally unique β-hairpin venom peptide from the predatory ant Anochetus emarginatus. Biochimica et Biophysica Acta (BBA) - General Subjects, 2016, 1860 (11), pp.2553-2562. ⟨10.1016/j.bbagen.2016.07.027⟩. ⟨hal-01511987⟩