A novel structural class of toxins: the methionine-rich peptides from the venoms of turrid marine snails (Mollusca, Conoidea)

• Published in: Toxicon (Oxford) 2004-03, Vol.43 (4), p.365-374
• Main Authors: López-Vera, Estuardo, Heimer de la Cotera, Edgar P, Maillo, Marı́a, Riesgo-Escovar, Juan R, Olivera, Baldomero M, Aguilar, Manuel B
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animal poisons toxicology. Antivenoms; Animals; Biological and medical sciences; Chromatography, High Pressure Liquid; Coiled-coil; Conoidea; Gemmula periscelida; Marine snails; Mass Spectrometry; Medical sciences; Methionine - chemistry; Methionine zipper; Methionine-rich; Mexico; Molecular Sequence Data; Mollusk Venoms - chemistry; Mollusk Venoms - genetics; Mollusk Venoms - isolation & purification; Peptides - chemistry; Peptides - genetics; Peptides - isolation & purification; Polystira albida; Protein Structure, Secondary; Seawater; Sequence Analysis, Protein; Snails - chemistry; Toxicology; Toxin; Turridae
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2003.12.008

The objective of this investigation was to purify and characterize polypeptides from the venom ducts of the turrid snails Polystira albida and Gemmula periscelida (superfamily: Conoidea, family: Turridae), collected in Mexican waters. Venoms of other groups in the superfamily (family: Conidae, genus: Conus) have peptide toxins (‘conotoxins’), but no venom components have been characterized from any turrid species. Crude venoms were fractionated using reversed-phase high performance liquid chromatography, and one major component from each venom was characterized. In contrast to most conotoxins, the polypeptides characterized contain a high proportion of Met, Tyr and Arg residues, and few, if any, Cys residues. The two peptides had some regions of homology, but were not significantly similar to other peptides. Both peptides are predicted to contain α-helical structures, and the peptide from P. albida is predicted to form a coiled-coil motif. This structural motif could provide conformational stability for these turrid venom components (‘turritoxins’), which in the case of conotoxins is primarily achieved by disulfide bonds. Thus, the first turritoxins characterized are strikingly different from the conotoxins, suggesting divergent biochemical strategies in the venoms of different major groups included in the superfamily Conoidea.