Proteome of fraction from Tityus serrulatus venom reveals new enzymes and toxins

Tityus serrulatus venom (Ts venom) is a complex mixture of several compounds with biotechnological and therapeutical potentials, which highlights the importance of the identification and characterization of these components. Although a considerable number of studies have been dedicated to the characterization of this complex cocktail, there is still a limitation of knowledge concerning its venom composition. Most of Ts venom studies aim to isolate and characterize their neurotoxins, which are small, basic proteins and are eluted with high buffer concentrations on cation exchange chromatography. The first and largest fraction from carboxymethyl cellulose-52 (CMC-52) chromatography of Ts venom, named fraction I (Fr I), is a mixture of proteins of high and low molecular masses, which do not interact with the cation exchange resin, being therefore a probable source of components still unknown of this venom. Thus, the present study aimed to perform the proteome study of Fraction I from Ts venom, by high resolution mass spectrometry, and its biochemical characterization, by the determination of several enzymatic activities. Methods: Fraction I was obtained by a cation exchange chromatography using 50 mg of crude venom. This fraction was subjected to a biochemical characterization, including determination of L-amino acid oxidase, phospholipase, hyaluronidase, proteases activities and inhibition of angiotensin converting enzyme (ACE) activity. Fraction I was submitted to reduction, alkylation and digestion processes, and the tryptic digested peptides obtained were analyzed in a Q-Exactive Orbitrap mass spectrometer. Data analysis was performed by PEAKS 8.5 software against NCBI database. Results: Fraction I exhibits proteolytic activity and it was able to inhibit ACE activity. Its proteome analysis identified 8 different classes of venom components, among them: neurotoxins (48%), metalloproteinases (21%), hypotensive peptides (11%), cysteine-rich venom protein (9%), antimicrobial peptides (AMP), phospholipases and other enzymes (chymotrypsin and lysozymes) (3%) and phosphodiesterases (2%). Conclusions: The combination of a proteomic and biochemical characterization strategies leads us to identify new components in the T. serrulatus scorpion venom. The proteome of venom´s fraction can provide valuable direction in the obtainment of components in their native forms in order to perform a preliminary characterization and, consequently, to promote advances in biological discoveries in toxinology.(AU)

Deep sequencing analysis of toad Rhinella schneideri skin glands and partial biochemical characterization of its cutaneous secretion

Animal poisons and venoms are sources of biomolecules naturally selected. Rhinella schneideri toads are widespread in the whole Brazilian territory and they have poison glands and mucous gland. Recently, protein from toads' secretion has gaining attention. Frog skin is widely known to present great number of host defense peptides and we hypothesize toads present them as well. In this study, we used a RNA-seq analysis from R. schneideri skin and biochemical tests with the gland secretion to unravel its protein molecules. Methods: Total RNA from the toad skin was extracted using TRizol reagent, sequenced in duplicate using Illumina Hiseq2500 in paired end analysis. The raw reads were trimmed and de novo assembled using Trinity. The resulting sequences were submitted to functional annotation against non-redundant NCBI database and Database of Anuran Defense Peptide. Furthermore, we performed caseinolytic activity test to assess the presence of serine and metalloproteases in skin secretion and it was fractionated by fast liquid protein chromatography using a reverse-phase column. The fractions were partially sequenced by Edman's degradation. Results: We were able to identify several classes of antimicrobial peptides, such as buforins, peroniins and brevinins, as well as PLA2, lectins and galectins, combining protein sequencing and RNA-seq analysis for the first time. In addition, we could isolate a PLA2 from the skin secretion and infer the presence of serine proteases in cutaneous secretion. Conclusions: We identified novel toxins and proteins from R. schneideri mucous glands. Besides, this is a pioneer study that presented the in depth characterization of protein molecules richness from this toad secretion. The results obtained herein showed evidence of novel AMP and enzymes that need to be further explored.(AU)

Peptidomic investigation of Neoponera villosa venom by high-resolution mass spectrometry: seasonal and nesting habitat variations

Background: Advancements in proteomics, including the technological improvement in instrumentation, have turned mass spectrometry into an indispensable tool in the study of venoms and toxins. In addition, the advance of nanoscale liquid chromatography coupled to nanoelectrospray mass spectrometry allows, due to its high sensitivity, the study of venoms from species previously left aside, such as ants. Ant venoms are a complex mixture of compounds used for defense, predation or communication purposes. The venom from Neoponera ants, a genus restricted to Neotropical regions, is known to have cytolytic, hemolytic, antimicrobial and insecticidal activities. Moreover, venoms from several Neoponera species have been compared and differences in their toxicity related to nesting habitat variation were reported. Therefore, the present study aimed to perform a deep peptidomic analysis of Neoponera villosa venom and a comparison of seasonal and nesting habitat variations using high-resolution mass spectrometry. Methods: Specimens of N. villosa ants were captured in Panga Natural Reserve (Uberlândia, MG, Brazil) from arboreal and ground-dwelling nests during summer and winter time. The venom glands were dissected, pooled and disrupted by ultra-sonic waves. The venom collected from different habitats (arboreal and ground-dwelling) and different seasons (summer and winter) was injected into a nanoACQUITY ULPC hyphened to a Q-Exactive Orbitrap mass spectrometer. The raw data were analyzed using PEAKS 7. Results: The results showed a molecular diversity of more than 500 peptides among these venoms, mostly in the mass range of 8004000 Da. Mutations and post-translational modifications were described and differences among the venoms were observed. Part of the peptides matched with ponericins, a well-known antimicrobial peptide family...

Peptidomic investigation of Neoponera villosa venom by high-resolution mass spectrometry: seasonal and nesting habitat variations

Advancements in proteomics, including the technological improvement in instrumentation, have turned mass spectrometry into an indispensable tool in the study of venoms and toxins. In addition, the advance of nanoscale liquid chromatography coupled to nanoelectrospray mass spectrometry allows, due to its high sensitivity, the study of venoms from species previously left aside, such as ants. Ant venoms are a complex mixture of compounds used for defense, predation or communication purposes. The venom from Neoponera ants, a genus restricted to Neotropical regions, is known to have cytolytic, hemolytic, antimicrobial and insecticidal activities. Moreover, venoms from several Neoponera species have been compared and differences in their toxicity related to nesting habitat variation were reported. Therefore, the present study aimed to perform a deep peptidomic analysis of Neoponera villosa venom and a comparison of seasonal and nesting habitat variations using high-resolution mass spectrometry. Methods: Specimens of N. villosa ants were captured in Panga Natural Reserve (Uberlândia, MG, Brazil) from arboreal and ground-dwelling nests during summer and winter time. The venom glands were dissected, pooled and disrupted by ultra-sonic waves. The venom collected from different habitats (arboreal and ground-dwelling) and different seasons (summer and winter) was injected into a nanoACQUITY ULPC hyphened to a Q-Exactive Orbitrap mass spectrometer. The raw data were analyzed using PEAKS 7. Results: The results showed a molecular diversity of more than 500 peptides among these venoms, mostly in the mass range of 800-4000 Da. Mutations and post-translational modifications were described and differences among the venoms were observed. Part of the peptides matched with ponericins, a well-known antimicrobial peptide family. In addition, smaller fragments related to ponericins were also identified, suggesting that this class of antimicrobial peptide might undergo enzymatic cleavages. Conclusion: There are substantial differences among the venom of N. villosa ants collected in different seasons and from different nest habitats. The venom composition is affected by climate changes that influence prey availability and predator presence. Clearly, nano-LC-MS boosted the knowledge about ant venom, a rich source of unexplored and promising bioactive compounds.(AU)