No abstract

Hemorrhage induced by snake venom metalloproteinases (SVMPs) is a complex phenomenon resulting in capillary disruption and blood extravasation. The mechanism of action of SVMPs has been investigated using various methodologies however the precise molecular events associated with microvessel disruption remains not fully understood. To gain insight into the hemorrhagic process, we analyzed the global effects of HF3, an extremely hemorrhagic SVMP from Bothrops jararaca, in the mouse skin and plasma. We report that in the HF3-treated skin there was evidence of degradation of extracellular matrix (collagens and proteoglycans), cytosolic, cytoskeleton, and plasma proteins. Furthermore, the data suggest that direct and indirect effects promoted by HF3 contributed to tissue injury as the activation of collagenases was detected in the HF3-treated skin. In the plasma analysis after depletion of the 20 most abundant proteins, fibronectin appeared as degraded by HF3. In contrast, some plasma proteinase inhibitors showed higher abundance compared to control skin and plasma. This is the first study to assess the complex in vivo effects of HF3 using high-throughput proteomic approaches, and the results underscore a scenario characterized by the interplay between the hydrolysis of intracellular, extracellular, and plasma proteins and the increase of plasma inhibitors in the hemorrhagic process.

No abstract

Only few studies on snake venoms were dedicated to deeply characterize the toxin secretion of animals from the Colubridae family, despite the fact that they represent the majority of snake diversity. As a consequence, some evolutionary trends observed in venom proteins that underpinned the evolutionary histories of snake toxins were based on data from a minor parcel of the clade. Here, we investigated the proteins of the totally unknown venom from Phalotris mertensi (Dipsadinae subfamily), in order to obtain a detailed profile of its toxins and to appreciate evolutionary tendencies occurring in colubrid venoms. By means of integrated omics and functional approaches, including RNAseq, Sanger sequencing, high-resolution proteomics, recombinant protein production, and enzymatic tests, we verified an active toxic secretion containing up to 21 types of proteins. A high content of Kunitz-type proteins and C-type lectins were observed, although several enzymatic components such as metalloproteinases and an L-amino acid oxidase were also present in the venom. Interestingly, an arguable venom component of other species was demonstrated as a true venom protein and named svLIPA (snake venom acid lipase). This finding indicates the importance of checking the actual protein occurrence across species before rejecting genes suggested to code for toxins, which are relevant for the discussion about the early evolution of reptile venoms. Moreover, trends in the evolution of some toxin classes, such as simplification of metalloproteinases and rearrangements of Kunitz and Wap domains, parallel similar phenomena observed in other venomous snake families and provide a broader picture of toxin evolution.