Qualitative and Quantitative Proteomic Analysis of Venoms from Mexican Rattlesnakes

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  Qualitative and Quantitative Proteomic Analysis of Venoms from Mexican Rattlesnakes Abstract Despite the vast biodiversity of Mexican vipers, venom of endemic species has been barely studied. Here we analyzed the venom composition of three endemic species of rattlesnakes: Crotalus aquilus , C. triseriatus , and C. ravus . We used quantitative chromato-mass-spectrometry and compared venoms with C. molossus , a species commonly found in North America, in a comparative and phylogenetic framework. In total, we identified 165 proteins grouped in 19 main protein families, consistent with previous reports for viperid venoms. In C. aquilus and C. triseriatus , the most predominant protein-family type was Serine Proteases, and in C. triseriatus and C. molossus it was Snake Venom Metalloproteases. The Label-free quantification revealed a high proportion of Snake Venom Metalloproteases in C. aquilus , C. triseriatus , and C. molossus , reaching 28–47% of the total venom. In contrast, in ...

Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers

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Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers

Abstract

Envenomation by viperid snakes causes acute muscle tissue injury (myonecrosis). An important group of myotoxic components comprises catalytically-inactive Lys49 phospholipase A2 homologs, which disrupt the integrity of the plasma membrane of skeletal muscle fibers through a mechanism that does not involve phospholipid hydrolysis. However, it remains unknown whether other mechanisms are involved in the cytotoxic action of these myotoxins. In this work, isolated calcium release channels (ryanodine receptor, RyR1) incorporated into an artificial lipid bilayer were used to study the action of the Lys49 phospholipase A2 homolog myotoxin II (Mt-II) from the venom of Bothrops asper. Mt-II induced a dose-dependent activation of the RyR1. The open probability of the channel increased with the dose of the toxin. The maximal conductance of the channel remained unchanged during the toxin treatment. Furthermore, the analysis of the open and closed states showed a slight toxin dependency of the latter. These findings suggest that, in addition to the calcium influx from the extracellular space through the disrupted plasma membrane, Ca2+ release from the internal stores may also occur. However, incubation of C2C12 myotubes in culture with the RyR1 antagonist dantrolene did not reduce the extent of cytotoxicity induced by Mt-II, suggesting that the RyR1-mediated increase in cytosolic Ca2+ does not contribute to the overall myotoxicity of this toxin.
Szentesi, P., Magyar, Z. É., Fernández, J., Csernoch, L., Ruiz-Campos, M., Lomonte, B., Gutiérrez, J. M., & Lopez-Dávila, A. J. (2025). Myotoxin II, a snake venom Lys49 phospholipase A2 homolog, induces activation of the ryanodine receptor in artificial bilayers. Toxicon, 108590. https://doi.org/10.1016/j.toxicon.2025.108590