Cone snails are predatory creatures using venom as a weapon for prey capture and defense. Since this venom is neurotoxic, the venom gland is considered as an enormous collection of pharmacologically interesting compounds having a broad spectrum of targets. As such, cone snail peptides represent an interesting treasure for drug development. Here, we report five novel peptides isolated from the venom of Conus longurionis, Conus asiaticus and Conus australis. Lo6/7a and Lo6/7b were retrieved from C. longurionis and have a cysteine framework VI/VII. Lo6/7b has an exceptional amino acid sequence because no similar conopeptide has been described to date (similarity percentage <50%). A third peptide, Asi3a from C. asiaticus, has a typical framework III Cys arrangement, classifying the peptide in the M-superfamily. Asi14a, another peptide of C. asiaticus, belongs to framework XIV peptides and has a unique amino acid sequence. Finally, AusB is a novel conopeptide from C. australis. The peptide has only one disulfide bond, but is structurally very different as compared to other disulfide-poor peptides. The peptides were screened on nAChRs, NaV and KV channels depending on their cysteine framework and proposed classification. No targets could be attributed to the peptides, pointing to novel functionalities. Moreover, in the quest of identifying novel pharmacological targets, the peptides were tested for antagonistic activity against a broad panel of Gram-negative and Gram-positive bacteria, as well as two yeast strains.
Keywords: Conus; antimicrobial tests; conotoxin; electrophysiology; peptide characterization.