Mass spectrometry strategies for venom mapping and peptide sequencing from crude venoms: case applications with single arthropod specimen

Comparative Proteomic Analysis of the Venoms from the Most Dangerous Scorpions in Morocco: Androctonus mauritanicus and Buthus occitanus

Morocco is known to harbor two of the world's most dangerous scorpion species: the black Androctonus mauritanicus (Am) and the yellow Buthus occitanus (Bo), responsible for 83% and 14% of severe envenomation cases, respectively. Scorpion venom is a mixture of biological molecules of variable structures and activities, most of which are proteins of low molecular weights referred to as toxins. In addition to toxins, scorpion venoms also contain biogenic amines, polyamines, and enzymes. With the aim of investigating the composition of the Am and Bo venoms, we conducted an analysis of the venoms by mass spectrometry (ESI-MS) after separation by reversed-phase HPLC chromatography. Results from a total of 19 fractions obtained for the Am venom versus 22 fractions for the Bo venom allowed the identification of approximately 410 and 252 molecular masses, respectively. In both venoms, the most abundant toxins were found to range between 2-5 kDa and 6-8 kDa. This proteomic analysis not only allowed the drawing of an extensive mass fingerprint of the Androctonus mauritanicus and Buthus occitanus venoms but also provided a better insight into the nature of their toxins.

Venom composition and pain-causing toxins of the Australian great carpenter bee Xylocopa aruana

Most species of bee are capable of delivering a defensive sting which is often painful. A solitary lifestyle is the ancestral state of bees and most extant species are solitary, but information on bee venoms comes predominantly from studies on eusocial species. In this study we investigated the venom composition of the Australian great carpenter bee, Xylocopa aruana Ritsema, 1876. We show that the venom is relatively simple, composed mainly of one small amphipathic peptide (XYTX₁-Xa1a), with lesser amounts of an apamin homologue (XYTX₂-Xa2a) and a venom phospholipase-A₂ (PLA₂). XYTX₁-Xa1a is homologous to, and shares a similar mode-of-action to melittin and the bombilitins, the major components of the venoms of the eusocial Apis mellifera (Western honeybee) and Bombus spp. (bumblebee), respectively. XYTX₁-Xa1a and melittin directly activate mammalian sensory neurons and cause spontaneous pain behaviours in vivo, effects which are potentiated in the presence of venom PLA₂. The apamin-like peptide XYTX₂-Xa2a was a relatively weak blocker of small conductance calcium-activated potassium (K_Ca) channels and, like A. mellifera apamin and mast cell-degranulating peptide, did not contribute to pain behaviours in mice. While the composition and mode-of-action of the venom of X. aruana are similar to that of A. mellifera, the greater potency, on mammalian sensory neurons, of the major pain-causing component in A. mellifera venom may represent an adaptation to the distinct defensive pressures on eusocial Apidae.

Profiling hymenopteran venom toxins: Protein families, structural landscape, biological activities, and pharmacological benefits

Hymenopterans are an untapped source of venom secretions. Their recent proteo-transcriptomic studies have revealed an extraordinary pool of toxins that participate in various biological processes, including pain, paralysis, allergic reactions, and antimicrobial activities. Comprehensive and clade-specific campaigns to collect hymenopteran venoms are therefore needed. We consider that data-driven bioprospecting may help prioritise sampling and alleviate associated costs. This work established the current protein landscape from hymenopteran venoms to evaluate possible sample bias by studying their origins, sequence diversity, known structures, and biological functions. We collected all 282 reported hymenopteran toxins (peptides and proteins) from the UniProt database that we clustered into 21 protein families from the three studied clades - wasps, bees, and ants. We identified 119 biological targets of hymenopteran toxins ranging from pathogen membranes to eukaryotic proteases, ion channels and protein receptors. Our systematic study further extended to hymenopteran toxins' therapeutic and biotechnological values, where we revealed promising applications in crop pests, human infections, autoimmune diseases, and neurodegenerative disorders.

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The hymenopteran toxin diversity includes 21 protein families from 81 species.

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Some toxins are shared across wasps, bees and ants, others are clade-specific.

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Their venoms contain membrane-active peptides, neurotoxins, allergens and enzymes.

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Hymenopteran toxins have been tested against a total of 119 biological targets.

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Hymenopteran toxins were predominantly evaluated as anti-infective agents.

Proteomic analysis of Red Sea Conus taeniatus venom reveals potential biological applications

Background:

Diverse and unique bioactive neurotoxins known as conopeptides or conotoxins are produced by venomous marine cone snails. Currently, these small and stable molecules are of great importance as research tools and platforms for discovering new drugs and therapeutics. Therefore, the characterization of Conus venom is of great significance, especially for poorly studied species.

Methods:

In this study, we used bioanalytical techniques to determine the venom profile and emphasize the functional composition of conopeptides in Conus taeniatus, a neglected worm-hunting cone snail.

Results:

The proteomic analysis revealed that 84.0% of the venom proteins were between 500 and 4,000 Da, and 16.0% were > 4,000 Da. In C. taeniatus venom, 234 peptide fragments were identified and classified as conotoxin precursors or non-conotoxin proteins. In this process, 153 conotoxin precursors were identified and matched to 23 conotoxin precursors and hormone superfamilies. Notably, the four conotoxin superfamilies T (22.87%), O1 (17.65%), M (13.1%) and O2 (9.8%) were the most abundant peptides in C. taeniatus venom, accounting for 63.40% of the total conotoxin diversity. On the other hand, 48 non-conotoxin proteins were identified in the venom of C. taeniatus. Moreover, several possibly biologically active peptide matches were identified, and putative applications of the peptides were assigned.

Conclusion:

Our study showed that the composition of the C. taeniatus-derived proteome is comparable to that of other Conus species and contains an effective mix of toxins, ionic channel inhibitors and antimicrobials. Additionally, it provides a guidepost for identifying novel conopeptides from the venom of C. taeniatus and discovering conopeptides of potential pharmaceutical importance.

Scorpion species of medical importance in the Brazilian Amazon: a review to identify knowledge gaps

Scorpionism is a relevant medical condition in Brazil. It is responsible for most accidents involving venomous animals in the country, which leads to severe symptoms that can evolve to death. In recent years, an increase of almost 50% in the incidence of scorpionism has been observed in the Northern Region, where the highest severity of envenoming has been notified since the beginning of the 21st century. This review aims to provide an in-depth assessment of public data and reports on symptoms and epidemiology of envenoming, ecological aspects of scorpions, and characterization of venoms and toxins to access the gaps that need to be filled in the knowledge of the scorpion species of medical importance from the Brazilian Amazon. A systematic search using the string words "Amazon" and "scorpion" was performed on 11 databases. No restriction on date, language or status of the publication was applied. Reports not related to the Brazilian Amazon were excluded. Therefore, 88 studies remained. It is shown that populations of scorpions of medical importance, even of the same species, may present significant toxic variations peculiar to some regions in the Brazilian Amazon, and commercial scorpion antivenoms were not able to shorten the intensity and duration of neurological manifestations in patients stung by T. silvestris, T. apiacas or T. obscurus. It is also highlighted that the toxins responsible for triggering these alterations have not been elucidated yet and this is a fruitful field for the development of more efficient antivenoms. Furthermore, the geographic distribution of scorpions of the genus Tityus in the Brazilian Amazon was revised and updated. The cumulative and detailed information provided in this review may help physicians and scientists interested in scorpionism in the Brazilian Amazon.

Mass spectrometry-based top-down and bottom-up approaches for proteomic analysis of the Moroccan Buthus occitanus scorpion venom

Buthus occitanus (B. occitanus) is one of the most dangerous scorpions in the world. Despite the involvement of B. occitanus scorpion in severe cases of envenomation in Morocco, no study has focused yet on the proteomic composition of the Moroccan B. occitanus scorpion venom. Mass spectrometry‐based proteomic techniques are commonly used in the study of scorpion venoms. The implementation of top‐down and bottom‐up approaches for proteomic analyses facilitates screening by allowing a global view of the structural aspects of such complex matrices. Here, we provide a partial overview of the venom of B. occitanus scorpion, in order to explore the diversity of its toxins and hereafter understand their effects. To this end, a combination of top‐down and bottom‐up approaches was applied using nano‐high liquid chromatography coupled to nano‐electrospray tandem mass spectrometry (nano‐LC‐ESI MS/MS). The LC‐MS results showed that B. occitanus venom contains around 200 molecular masses ranging from 1868 to 16 720 Da, the most representative of which are those between 5000 and 8000 Da. Interestingly, combined top‐down and bottom‐up LC‐MS/MS results allowed the identification of several toxins, which were mainly those acting on ion channels, including those targeting sodium (NaScTxs), potassium (KScTxs), chloride (ClScTxs), and calcium channels (CaScTx), as well as antimicrobial peptides (AMPs), amphipathic peptides, myotropic neuropeptides, and hypothetical secreted proteins. This study reveals the molecular diversity of B. occitanus scorpion venom and identifies components that may have useful pharmacological activities.

Actividad neurotóxica del veneno de serpientes del género Micrurus y métodos para su análisis. Revisión de la literatura

Introducción. Las serpientes del género Micrurus son animales de hábitos fosoriales, de temperamento pasivo y escasa producción de un potente veneno con características neurotóxicas que bloquean la transmisión sináptica en la placa neuromuscular.Objetivo. Presentar un panorama general de la neurotoxicidad del veneno de las serpientes Micrurus y su caracterización funcional mediante métodos de análisis ex vivo.Materiales y métodos. Se realizó una revisión de la literatura en MedLine y ScienceDirect usando términos específicos y sus combinaciones. Estrategia de búsqueda: tipo de estudios: artículos sobre la neurotoxicidad del veneno de serpientes Micrurus y técnicas para determinar su actividad neurotóxica mediante modelos in vitro, in vivo y ex vivo; periodo de publicación: sin limite inicial a junio de 2018; idiomas: inglés y español.Resultados. De los 88 estudios identificados en la búsqueda inicial, se excluyeron 28 por no cumplir los criterios de inclusión (basándose en la lectura de títulos y resúmenes); además, se incluyeron 8 documentos adicionales (libros e informes), que, a criterio de los autores, complementaban la información reportada por las referencias seleccionadas. Los estudios incluidos en la revisión (n=68) correspondieron a las siguientes tipologías: investigaciones originales (n=44), artículos de revisión (n=16) y capítulos de libros, informes, guías y consultas en internet (n=8).Conclusiones. Los estudios que describen el uso de preparaciones ex vivo de músculo y nervio para evaluar el efecto de neurotoxinas ofrecen un buen modelo para la caracterización del efecto presináptico y postsináptico del veneno producido por las serpientes Micrurus.

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 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.

Electronic supplementary material

The online version of this article (10.1186/s40409-018-0141-3) contains supplementary material, which is available to authorized users.

Origins, Technological Development, and Applications of Peptidomics

Peptidomics is the comprehensive characterization of peptides from biological sources mainly by HPLC and mass spectrometry. Mass spectrometry allows the detection of a multitude of single peptides in complex mixtures. The term first appeared in full papers in the year 2001, after over 100 years of peptide research with a main focus on one or a few specific peptides. Within the last 15 years, this new field has grown to over 1200 publications. Mass spectrometry techniques, in combination with other analytical methods, were developed for the fast and comprehensive analysis of peptides in proteomics and specifically adjusted to implement peptidomics technologies. Although peptidomics is closely linked to proteomics, there are fundamental differences with conventional bottom-up proteomics. The development of peptidomics is described, including the most important implementations for its technological basis. Different strategies are covered which are applied to several important applications, such as neuropeptidomics and discovery of bioactive peptides or biomarkers. This overview includes links to all other chapters in the book as well as recent developments of separation, mass spectrometric, and data processing technologies. Additionally, some new applications in food and plant peptidomics as well as immunopeptidomics are introduced.

Proteomic Characterization of the Venom of Five Bombus (Thoracobombus) Species

Venomous animals use venom, a complex biofluid composed of unique mixtures of proteins and peptides, to act on vital systems of the prey or predator. In bees, venom is solely used for defense against predators. However, the venom composition of bumble bees (Bombus sp.) is largely unknown. The Thoracobombus subgenus of Bombus sp. is a diverse subgenus represented by 14 members across Turkey. In this study, we sought out to proteomically characterize the venom of five Thoracobombus species by using bottom-up proteomic techniques. We have obtained two-dimensional polyacrylamide gel (2D-PAGE) images of each species’ venom sample. We have subsequently identified the protein spots by using matrix assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS). We have identified 47 proteins for Bombus humilis, 32 for B. pascuorum, 60 for B. ruderarius, 39 for B. sylvarum, and 35 for B. zonatus. Moreover, we illustrated that intensities of 2DE protein spots corresponding to putative venom toxins vary in a species-specific manner. Our analyses provide the primary proteomic characterization of five bumble bee species’ venom composition.

Peptidomic analysis of the venom of the solitary bee Xylocopa appendiculata circumvolans

Background

Among the hymenopteran insect venoms, those from social wasps and bees – such as honeybee, hornets and paper wasps – have been well documented. Their venoms are composed of a number of peptides and proteins and used for defending their nests and themselves from predators. In contrast, the venoms of solitary wasps and bees have not been the object of further research. In case of solitary bees, only major peptide components in a few venoms have been addressed. Therefore, the aim of the present study was to explore the peptide component profile of the venom from the solitary bee Xylocopa appendiculata circumvolans by peptidomic analysis with using LC-MS.

Methods

A reverse-phase HPLC connected to ESI-OrbiTrap MS was used for LC-MS. On-line mass fingerprinting was made from TIC, and data-dependent tandem mass spectrometry gave MSMS spectra. A major peptide component was isolated by reverse-phase HPLC by conventional way, and its sequence was determined by Edman degradation, which was finally corroborated by solid phase synthesis. Using the synthetic specimen, biological activities (antimicrobial activity, mast cell devaluation, hemolysis, leishmanicidal activity) and pore formation in artificial lipid bilayer were evaluated.

Results

On-line mass fingerprinting revealed that the crude venom contained 124 components. MS/MS analysis gave 75 full sequences of the peptide components. Most of these are related to the major and novel peptide, xylopin. Its sequence, GFVALLKKLPLILKHLH-NH₂, has characteristic features of linear cationic α-helical peptides; rich in hydrophobic and basic amino acids with no disulfide bond, and accordingly, it can be predicted to adopt an amphipathic α-helix secondary structure. In biological evaluation, xylopin exhibited broad-spectrum antimicrobial activity, and moderate mast cell degranulation and leishmanicidal activities, but showed virtually no hemolytic activity. Additionally, the peptide was able to incorporate pores in artificial lipid bilayers of azolectin, confirming the mechanism of the cytolytic activity by pore formation in biological membranes.

Conclusions

LC-ESI-MS and MS/MS analysis of the crude venom extract from a solitary bee Xylocopa appendiculata circumvolans revealed that the component profile of this venom mostly consisted of small peptides. The major peptide components, xylopin and xylopinin, were purified and characterized in a conventional manner. Their chemical and biological characteristics, belonging to linear cationic α-helical peptides, are similar to the known solitary bee venom peptides, melectin and osmin. Pore formation in artificial lipid bilayers was demonstrated for the first time with a solitary bee peptide.

Structure-Activity Relationships of Insect Defensins

Insects make up the largest and most diverse group of organisms on earth with several million species to exist in total. Considering the sheer number of insect species and the vast variety of ways they interact with their environment through chemistry, it is clear that they have significant potential as a source of new lead molecules. They have adapted to a range of ecological habitats and exhibit a symbiotic lifestyle with various microbes such as bacteria and fungi. Accordingly, numerous antimicrobial compounds have been identified including for example defensin peptides. Insect defensins were found to have broad-spectrum activity against various gram-positive/negative bacteria as well as fungi. They exhibit a unique structural topology involving the complex arrangement of three disulfide bonds as well as an alpha helix and beta sheets, which is known as cysteine-stabilized αβ motif. Their stability and amenability to peptide engineering make them promising candidates for the development of novel antibiotics lead molecules. This review highlights the current knowledge regarding the structure-activity relationships of insect defensin peptides and provides basis for future studies focusing on the rational design of novel cysteine-rich antimicrobial peptides.

Individual variability of venom from the European adder (Vipera berus berus) from one locality in Eastern Hungary

We have revealed intra-population variability among venom samples from several individual European adders (Vipera berus berus) within a defined population in Eastern Hungary. Individual differences in venom pattern were noticed, both gender-specific and age-related, by one-dimensional electrophoresis. Gelatin zymography demonstrated that these individual venoms have different degradation profiles indicating varying protease activity in the specimens from adders of different ages and genders. Some specimens shared a conserved region of substrate degradation, while others had lower or extremely low protease activity. Phospholipase A₂ activity of venoms was similar but not identical. Interspecimen diversity of the venom phospholipase A₂-spectra (based on the components' molecular masses) was detected by MALDI-TOF MS. The lethal toxicity of venoms (LD₅₀) also showed differences among individual snakes. Extracted venom samples had varying neuromuscular paralysing effect on chick biventer cervicis nerve-muscle preparations. The paralysing effect of venom was lost when calcium in the physiological salt solution was replaced by strontium; indicating that the block of twitch responses to nerve stimulation is associated with the activity of a phospholipase-dependent neurotoxin. In contrast to the studied V. b. berus venoms from different geographical regions so far, this is the first V. b. berus population discovered to have predominantly neurotoxic neuromuscular activity. The relevance of varying venom yields is also discussed. This study demonstrates that individual venom variation among V. b. berus living in particular area of Eastern Hungary might contribute to a wider range of clinical manifestations of V. b. berus envenoming than elsewhere in Europe.

Isolation of biologically active peptides from the venom of Japanese carpenter bee, Xylocopa appendiculata

Background

Mass spectrometry-guided venom peptide profiling is a powerful tool to explore novel substances from venomous animals in a highly sensitive manner. In this study, this peptide profiling approach is successfully applied to explore the venom peptides of a Japanese solitary carpenter bee, Xylocopa appendiculata (Hymenoptera: Apoidea: Apidae: Anthophila: Xylocopinae: Xylocopini). Although interesting biological effects of the crude venom of carpenter bees have been reported, the structure and biological function of the venom peptides have not been elucidated yet.

Methods

The venom peptide profiling of the crude venom of X. appendiculata was performed by matrix-assisted laser desorption/ionization-time of flight mass spectroscopy. The venom was purified by a reverse-phase HPLC. The purified peptides were subjected to the Edman degradation, MS/MS analysis, and/or molecular cloning methods for peptide sequencing. Biological and functional characterization was performed by circular dichroism analysis, liposome leakage assay, and antimicrobial, histamine releasing and hemolytic activity tests.

Results

Three novel peptides with m/z 16508, 1939.3, and 1900.3 were isolated from the venom of X. appendiculata. The peptide with m/z 16508 was characterized as a secretory phospholipase A₂ (PLA₂) homolog in which the characteristic cysteine residues as well as the active site residues found in bee PLA₂s are highly conserved. Two novel peptides with m/z 1939.3 and m/z 1900.3 were named as Xac-1 and Xac-2, respectively. These peptides are found to be amphiphilic and displayed antimicrobial and hemolytic activities. The potency was almost the same as that of mastoparan isolated from the wasp venom.

Conclusion

We found three novel biologically active peptides in the venom of X. appendiculata and analyzed their molecular functions, and compared their sequential homology to discuss their molecular diversity. Highly sensitive mass analysis plays an important role in this study.

Electronic supplementary material

The online version of this article (doi:10.1186/s40409-017-0119-6) contains supplementary material, which is available to authorized users.

Advances in venomics

The term “venomics” was coined to describe the global study of venom and venom glands, targeting comprehensive characterization of the whole toxin profile of a venomous animal by means of proteomics, transcriptomics, genomics and bioinformatics studies.

ω-Tbo-IT1-New Inhibitor of Insect Calcium Channels Isolated from Spider Venom

Novel disulfide-containing polypeptide toxin was discovered in the venom of the Tibellus oblongus spider. We report on isolation, spatial structure determination and electrophysiological characterization of this 41-residue toxin, called ω-Tbo-IT1. It has an insect-toxic effect with LD50 19 μg/g in experiments on house fly Musca domestica larvae and with LD50 20 μg/g on juvenile Gromphadorhina portentosa cockroaches. Electrophysiological experiments revealed a reversible inhibition of evoked excitatory postsynaptic currents in blow fly Calliphora vicina neuromuscular junctions, while parameters of spontaneous ones were not affected. The inhibition was concentration dependent, with IC50 value 40 ± 10 nM and Hill coefficient 3.4 ± 0.3. The toxin did not affect frog neuromuscular junctions or glutamatergic and GABAergic transmission in rat brains. Ca(2+) currents in Calliphora vicina muscle were not inhibited, whereas in Periplaneta americana cockroach neurons at least one type of voltage gated Ca(2+) current was inhibited by ω-Tbo-IT1. Thus, the toxin apparently acts as an inhibitor of presynaptic insect Ca(2+) channels. Spatial structure analysis of the recombinant ω-Tbo-IT1 by NMR spectroscopy in aqueous solution revealed that the toxin comprises the conventional ICK fold containing an extended β-hairpin loop and short β-hairpin loop which are capable of making "scissors-like mutual motions".

Ecological venomics: How genomics, transcriptomics and proteomics can shed new light on the ecology and evolution of venom

Animal venom is a complex cocktail of bioactive chemicals that traditionally drew interest mostly from biochemists and pharmacologists. However, in recent years the evolutionary and ecological importance of venom is realized as this trait has direct and strong influence on interactions between species. Moreover, venom content can be modulated by environmental factors. Like many other fields of biology, venom research has been revolutionized in recent years by the introduction of systems biology approaches, i.e., genomics, transcriptomics and proteomics. The employment of these methods in venom research is known as 'venomics'. In this review we describe the history and recent advancements of venomics and discuss how they are employed in studying venom in general and in particular in the context of evolutionary ecology. We also discuss the pitfalls and challenges of venomics and what the future may hold for this emerging scientific field.

Transcriptomics and venomics: implications for medicinal chemistry

Over the last three decades, transcriptomic studies of venom gland cells have continuously evolved, opening up new possibilities for exploring the molecular diversity of animal venoms, a prerequisite for the discovery of new drug candidates and molecular phylogenetics. The molecular complexity of animal venoms is much greater than initially thought. In this review, we describe the different technologies available for transcriptomic studies of venom, from the original individual cloning approaches to the more recent global Next Generation Sequencing strategies. Our understanding of animal venoms is evolving, with the discovery of complex and diverse bio-optimized cocktails of compounds, including mostly peptides and proteins, which are now beginning to be studied by academic and industrial researchers.

Unraveling the venom proteome of the bumblebee (Bombus terrestris) by integrating a combinatorial peptide ligand library approach with FT-ICR MS

Within the Apidae, the largest family of bees with over 5600 described species, the honeybee is the sole species with a well studied venom proteome. So far, only little research has focused on bumblebee venom. Recently, the genome sequence of the European large earth bumblebee (Bombus terrestris) became available and this allowed the first in-depth proteomic analysis of its venom composition. We identified 57 compounds, with 52 of them never described in bumblebee venom. Remarkably, 72% of the detected compounds were found to have a honeybee venom homolog, which reflects the similar defensive function of both venoms and the high degree of homology between both genomes. However, both venoms contain a selection of species-specific toxins, revealing distinct damaging effects that may have evolved in response to species-specific attackers. Further, this study extends the list of potential venom allergens. The availability of both the honeybee and bumblebee venom proteome may help to develop a strategy that solves the current issue of false double sensitivity in allergy diagnosis, which is caused by cross-reactivity between both venoms. A correct diagnosis is important as it is recommended to perform an immunotherapy with venom of the culprit species.

Diversity of peptide toxins from stinging ant venoms

Ants (Hymenoptera: Formicidae) represent a taxonomically diverse group of arthropods comprising nearly 13,000 extant species. Sixteen ant subfamilies have individuals that possess a stinger and use their venom for purposes such as a defence against predators, competitors and microbial pathogens, for predation, as well as for social communication. They exhibit a range of activities including antimicrobial, haemolytic, cytolytic, paralytic, insecticidal and pain-producing pharmacologies. While ant venoms are known to be rich in alkaloids and hydrocarbons, ant venoms rich in peptides are becoming more common, yet remain understudied. Recent advances in mass spectrometry techniques have begun to reveal the true complexity of ant venom peptide composition. In the few venoms explored thus far, most peptide toxins appear to occur as small polycationic linear toxins, with antibacterial properties and insecticidal activity. Unlike other venomous animals, a number of ant venoms also contain a range of homodimeric and heterodimeric peptides with one or two interchain disulfide bonds possessing pore-forming, allergenic and paralytic actions. However, ant venoms seem to have only a small number of monomeric disulfide-linked peptides. The present review details the structure and pharmacology of known ant venom peptide toxins and their potential as a source of novel bioinsecticides and therapeutic agents.

A Polychaete's powerful punch: venom gland transcriptomics of Glycera reveals a complex cocktail of toxin homologs

Glycerids are marine annelids commonly known as bloodworms. Bloodworms have an eversible proboscis adorned with jaws connected to venom glands. Bloodworms prey on invertebrates, and it is known that the venom glands produce compounds that can induce toxic effects in animals. Yet, none of these putative toxins has been characterized on a molecular basis. Here we present the transcriptomic profiles of the venom glands of three species of bloodworm, Glycera dibranchiata, Glycera fallax and Glycera tridactyla, as well as the body tissue of G. tridactyla. The venom glands express a complex mixture of transcripts coding for putative toxin precursors. These transcripts represent 20 known toxin classes that have been convergently recruited into animal venoms, as well as transcripts potentially coding for Glycera-specific toxins. The toxins represent five functional categories: Pore-forming and membrane-disrupting toxins, neurotoxins, protease inhibitors, other enzymes, and CAP domain toxins. Many of the transcripts coding for putative Glycera toxins belong to classes that have been widely recruited into venoms, but some are homologs of toxins previously only known from the venoms of scorpaeniform fish and monotremes (stonustoxin-like toxin), turrid gastropods (turripeptide-like peptides), and sea anemones (gigantoxin I-like neurotoxin). This complex mixture of toxin homologs suggests that bloodworms employ venom while predating on macroscopic prey, casting doubt on the previously widespread opinion that G. dibranchiata is a detritivore. Our results further show that researchers should be aware that different assembly methods, as well as different methods of homology prediction, can influence the transcriptomic profiling of venom glands.

Sample limited characterization of a novel disulfide-rich venom peptide toxin from terebrid marine snail Terebra variegata

Disulfide-rich peptide toxins found in the secretions of venomous organisms such as snakes, spiders, scorpions, leeches, and marine snails are highly efficient and effective tools for novel therapeutic drug development. Venom peptide toxins have been used extensively to characterize ion channels in the nervous system and platelet aggregation in haemostatic systems. A significant hurdle in characterizing disulfide-rich peptide toxins from venomous animals is obtaining significant quantities needed for sequence and structural analyses. Presented here is a strategy for the structural characterization of venom peptide toxins from sample limited (4 ng) specimens via direct mass spectrometry sequencing, chemical synthesis and NMR structure elucidation. Using this integrated approach, venom peptide Tv1 from Terebra variegata was discovered. Tv1 displays a unique fold not witnessed in prior snail neuropeptides. The novel structural features found for Tv1 suggest that the terebrid pool of peptide toxins may target different neuronal agents with varying specificities compared to previously characterized snail neuropeptides.

Miniaturized bioaffinity assessment coupled to mass spectrometry for guided purification of bioactives from toad and cone snail

A nano-flow high-resolution screening platform, featuring a parallel chip-based microfluidic bioassay and mass spectrometry coupled to nano-liquid chromatography, was applied to screen animal venoms for nicotinic acetylcholine receptor like (nAChR) affinity by using the acetylcholine binding protein, a mimic of the nAChR. The potential of this microfluidic platform is demonstrated by profiling the Conus textile venom proteome, consisting of over 1,000 peptides. Within one analysis (<90 min, 500 ng venom injected), ligands are detected and identified. To show applicability for non-peptides, small molecular ligands such as steroidal ligands were identified in skin secretions from two toad species (Bufo alvarius and Bufo marinus). Bioactives from the toad samples were subsequently isolated by MS-guided fractionation. The fractions analyzed by NMR and a radioligand binding assay with α7-nAChR confirmed the identity and bioactivity of several new ligands.

Peptide diversity in the venom of the social wasp Polybia paulista (Hymenoptera): a comparison of the intra- and inter-colony compositions

The venoms of the social wasps evolved to be used as defensive tools to protect the colonies of these insects against the attacks of predators. Previous studies estimated the presence of a dozen peptide components in the venoms of each species of these insects, which altogether comprise up to 70% of the weight of freeze-dried venoms. In the present study, an optimized experimental protocol is reported that utilizes liquid chromatography coupled to electrospray ionization mass spectrometry for the detection of peptides in the venom of the social wasp Polybia paulista; peptide profiles for both intra- and inter-colonial comparisons were obtained using this protocol. The results of our study revealed a surprisingly high level of intra- and inter-colonial variability for the same wasp species. We detected 78-108 different peptides in the venom of different colonies of P. paulista in the molar mass range from 400 to 3000Da; among those, only 36 and 44 common peptides were observed in the inter- and intra-colony comparisons, respectively.

Strategies in mass spectrometry for the assignment of Cys-Cys disulfide connectivities in proteins

Elucidating disulfide linkage patterns is a crucial part of protein characterization, for which mass spectrometry (MS) is now an indispensable analytical tool. In many cases, MS-based disulfide connectivity assignment is straightforwardly achieved using one-step protein fragmentation in the unreduced form followed by mass measurement of bridged fragments. By contrast, venom proteins, which are receiving increasing interest as potential therapeutics, are a challenge for MS-based disulfide assignment due to their numerous closely spaced cysteines and knotted disulfide structure, requiring creative strategies to determine their connectivity. Today, these include the use of an array of reagents for enzymatic and/or chemical cleavage, partial reduction, differential cysteine labeling and tandem MS. This review aims to describe the toolkit of techniques available to MS users approaching both straightforward and complex disulfide bridge assignments, with a particular focus on strategies utilizing standard instrumentation found in a well-equipped analytical or proteomics laboratory.

Two peptides, TsAP-1 and TsAP-2, from the venom of the Brazilian yellow scorpion, Tityus serrulatus: evaluation of their antimicrobial and anticancer activities

Here we report two novel 17-mer amidated linear peptides (TsAP-1 and TsAP-2) whose structures were deduced from cDNAs cloned from a venom-derived cDNA library of the Brazilian yellow scorpion, Tityus serrulatus. Both mature peptides were structurally-characterised following their location in chromatographic fractions of venom and synthetic replicates of each were subjected to a range of biological assays. The peptides were each active against model test micro-organisms but with different potencies. TsAP-1 was of low potency against all three test organisms (MICs 120-160 μM), whereas TsAP-2 was of high potency against the Gram-positive bacterium, Staphylococcus aureus (MIC 5 μM) and the yeast, Candida albicans (10 μM). Haemolytic activity of TsAP-1 was low (4% at 160 μM) and in contrast, that of TsAP-2 was considerably higher (18% at 20 μM). Substitution of four neutral amino acid residues with Lys residues in each peptide had dramatic effects on their antimicrobial potencies and haemolytic activities, particularly those of TsAP-1. The MICs of the enhanced cationic analogue (TsAP-S1) were 2.5 μM for S. aureus/C. albicans and 5 μM for E. coli but with an associated large increase in haemolytic activity (30% at 5 μM). The same Lys residue substitutions in TsAP-2 produced a dramatic effect on its MIC for E. coli lowering this from >320 μM to 5 μM. TsAP-1 was ineffective against three of the five human cancer cell lines tested while TsAP-2 inhibited the growth of all five. Lys residue substitution of both peptides enhanced their potency against all five cell lines with TsAp-S2 being the most potent with IC50 values ranging between 0.83 and 2.0 μM. TsAP-1 and TsAP-2 are novel scorpion venom peptides with broad spectrum antimicrobial and anticancer cell activities the potencies of which can be significantly enhanced by increasing their cationicity.

Towards an integrated venomics approach for accelerated conopeptide discovery

Conopeptides and conotoxins are small peptides produced by cone snails as a part of their predatory/defense strategies that target key ion channels and receptors in the nervous system. Some of these peptides also potently target mammalian ion channels involved in pain pathways. As a result, these venoms are a source of valuable pharmacological and therapeutic agents. The traditional approach towards conopeptide discovery relied on activity-guided fractionation, which is time consuming and resource-intensive. In this review, we discuss the advances in the fields of transcriptomics, proteomics and bioinformatics that now allow researchers to integrate these three platforms towards a more efficient discovery strategy. In this review, we also highlight the challenges associated with the wealth of data generated with this integrated approach and briefly discuss the impact these methods could have on the field of toxinology.

Venoms as a platform for human drugs: translating toxins into therapeutics

INTRODUCTION

An extraordinarily diverse range of animals have evolved venoms for predation, defence, or competitor deterrence. The major components of most venoms are peptides and proteins that are often protease-resistant due to their disulfide-rich architectures. Some of these toxins have become valuable as pharmacological tools and/or therapeutics due to their extremely high specificity and potency for particular molecular targets. There are currently six FDA-approved drugs derived from venom peptides or proteins.

AREAS COVERED

This article surveys the current pipeline of venom-derived therapeutics and critically examines the potential of peptide and protein drugs derived from venoms. Emerging trends are identified, including an increasing industry focus on disulfide-rich venom peptides and the use of a broader array of molecular targets in order to develop venom-based therapeutics for treating a wider range of clinical conditions.

EXPERT OPINION

Key technical advances in combination with a renewed industry-wide focus on biologics have converged to provide a larger than ever pipeline of venom-derived therapeutics. Disulfide-rich venom peptides obviate some of the traditional disadvantages of therapeutic peptides and some may be suitable for oral administration. Moreover, some venom peptides can breach the blood brain barrier and translocate across cell membranes, which opens up the possibility of exploiting molecular targets not previously accessible to peptide drugs.

Molecular diversity of toxic components from the scorpion Heterometrus petersii venom revealed by proteomic and transcriptome analysis

Scorpion venoms contain a vast untapped reservoir of natural products, which have the potential for medicinal value in drug discovery. In this study, toxin components from the scorpion Heterometrus petersii venom were evaluated by transcriptome and proteome analysis.Ten known families of venom peptides and proteins were identified, which include: two families of potassium channel toxins, four families of antimicrobial and cytolytic peptides,and one family from each of the calcium channel toxins, La1-like peptides, phospholipase A2,and the serine proteases. In addition, we also identified 12 atypical families, which include the acid phosphatases, diuretic peptides, and ten orphan families. From the data presented here, the extreme diversity and convergence of toxic components in scorpion venom was uncovered. Our work demonstrates the power of combining transcriptomic and proteomic approaches in the study of animal venoms.

Dramatic intraspecimen variations within the injected venom of Conus consors: an unsuspected contribution to venom diversity

With the advent of highly sensitive mass spectrometry techniques, the minute amount of various secretions produced by living animals can be studied to a level of details never attained before. In this study, we used LC-ESI-MS to analyse the injected venom of an indo-pacific piscivorous cone snail, Conus consors. While long-term follow up of several captive specimens have revealed a typical "venom fingerprint" for this species, dramatic variations were also observed. In the most extreme case, a single cone snail unexpectedly produced two very distinct venom profiles containing completely different sets of peptides with no overlap of detected masses. Surprisingly, there was no correlation between the peptides produced in the venom duct and those obtained after milking live cone snails, implying yet unknown mechanisms of selection and regulation. Our study defines the notion of intraspecimen variation and demonstrates how this phenomenon contributes to the overall venom diversity.

Fusion and retrotransposition events in the evolution of the sea anemone Anemonia viridis neurotoxin genes

Sea anemones are sessile predators that use a variety of toxins to paralyze prey and foe. Among these toxins, Types I, II and III are short peptides that affect voltage-gated sodium channels. Anemonia viridis is the only sea anemone species that produces both Types I and III neurotoxin. Although the two toxin types are unrelated in sequence and three-dimensional structure, cloning and comparative analysis of their loci revealed a highly similar sequence at the 5' region, which encodes a signal peptide. This similarity was likely generated by gene fusion and could be advantageous in transcript stability and intracellular trafficking and secretion. In addition, these analyses identified the processed pseudogenes of the two gene families in the genome of A. viridis, probably resulting from retrotransposition events. As presence of processed pseudogenes in the genome requires transcription in germ-line cells, we analyzed oocyte-rich ovaries and found that indeed they contain Types I and III transcripts. This result raises questions regarding the role of toxin transcripts in these tissues. Overall, the retrotransposition and gene fusion events suggest that the genes of both Types I and III neurotoxins evolved in a similar fashion and share a partial common ancestry.

Structural biology of allergens from stinging and biting insects

PURPOSE OF REVIEW

Modern techniques in genomic and protein research are applied to the study of stinging and biting insect allergens.

RECENT FINDINGS

Three-dimensional structures of additional insect venom and salivary allergens have been determined. An approach to determining B-cell epitopes has been used for hyaluronidase. A number of new venom and salivary allergens have been characterized. The structures and significance of several insect allergens have been updated. Investigations continue into distinguishing venom crossreactivity from multiple sensitization. Further studies are clarifying the significance of carbohydrate epitopes. Genomic and proteomic techniques are being used in the investigation of proteins and peptides in insect venom and saliva.

SUMMARY

The nature of venom crossreactivity and the B-cell and T-cell epitope structures of insect venom and salivary allergens are beginning to be elucidated.