Mipartoxin-I, a novel three-finger toxin, is the major neurotoxic component in the venom of the redtail coral snake Micrurus mipartitus (Elapidae).
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.
Programa de Ofidismo y Escorpionismo, Universidad de Antioquia, Medellín, Colombia.
Paola
P
Rey-Suárez
Rafael Stuani
RS
Floriano
Sandro
S
Rostelato-Ferreira
Mónica
M
Saldarriaga-Córdoba
Vitelbina
V
Núñez
Léa
L
Rodrigues-Simioni
Bruno
B
Lomonte
D000595:Amino Acid Sequence; D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D002845:Chromatography; D003105:Colombia; D004546:Elapid Venoms / Q000737:chemistry* / Q000235:genetics*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004546:Elapid Venoms; C099850:alpha-neurotoxin, Micrurus