Mipartoxin-I, a novel three-finger toxin, is the major neurotoxic component in the venom of the redtail coral snake Micrurus mipartitus (Elapidae)

• Published in: Toxicon (Oxford) Vol. 60; no. 5; pp. 851 - 863
• Main Authors: Rey-Suárez, Paola, Floriano, Rafael Stuani, Rostelato-Ferreira, Sandro, Saldarriaga-Córdoba, Mónica, Núñez, Vitelbina, Rodrigues-Simioni, Léa, Lomonte, Bruno
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2012; Elsevier
• Subjects: Amino Acid Sequence; Analysis of Variance; Animal poisons toxicology. Antivenoms; Animals; Base Sequence; Bayes Theorem; Biological and medical sciences; Chromatography; Colombia; Elapid Venoms - chemistry; Elapid Venoms - genetics; Male; Medical sciences; Membrane Potentials - drug effects; Mice; Micrurus mipartitus; Mipartoxin-I; Models, Genetic; Models, Molecular; Molecular Sequence Data; Neurotoxicity; Phylogeny; Protein Conformation; Sequence Alignment; Sequence Analysis, DNA; Sequence Homology; Snake venom; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Three-finger toxin; Toxicology; Colombia; Three-finger toxin; Snake venom; Neurotoxicity; Mipartoxin-I; Micrurus mipartitus; Nervous system diseases; Toxicity; Animal origin; Nervous system; Ophidia; Toxin; Vertebrata; Venom; Reptilia
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2012.05.023

The major venom component of Micrurus mipartitus, a coral snake distributed from Nicaragua to northern South America, was characterized biochemically and functionally. This protein, named mipartoxin-I, is a novel member of the three-finger toxin superfamily, presenting the characteristic cysteine signature and amino acid sequence length of the short-chain, type-I, α-neurotoxins. Nevertheless, it varies considerably from related toxins, with a sequence identity not higher than 70% in a multiple alignment of 67 proteins within this family. Its observed molecular mass (7030.0) matches the value predicted by its amino acid sequence, indicating lack of post-translational modifications. Mipartoxin-I showed a potent lethal effect in mice (intraperitoneal median lethal dose: 0.06 μg/g body weight), and caused a clear neuromuscular blockade on both avian and mouse nerve-muscle preparations, presenting a post-synaptic action through the cholinergic nicotinic receptor. Since mipartoxin-I is the most abundant (28%) protein in M. mipartitus venom, it should play a major role in its toxicity, and therefore represents an important target for developing a therapeutic antivenom, which is very scarce or even unavailable in the regions where this snake inhabits. The structural information here provided might help in the preparation of a synthetic or recombinant immunogen to overcome the limited venom availability. ► The major venom protein of Micrurus mipartitus (redtail coral snake) was isolated and characterized. ► It is a novel α-neurotoxin of the three-finger toxin superfamily. ► Its complete amino acid sequence was determined. ► Due to its abundance and lethal potency, it should be a relevant target for the development of an antivenom.