1
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Warrell DA, Williams DJ. Clinical aspects of snakebite envenoming and its treatment in low-resource settings. Lancet 2023; 401:1382-1398. [PMID: 36931290 DOI: 10.1016/s0140-6736(23)00002-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 11/26/2022] [Accepted: 12/18/2022] [Indexed: 03/16/2023]
Abstract
There is increasing recognition of the public health importance of snakebite envenoming. Worldwide annual incidence is likely to be 5 million bites, with mortality exceeding 150 000 deaths, and the resulting physical and psychological morbidity leads to substantial social and economic repercussions. Prevention through community education by trained health workers is the most effective and economically viable strategy for reducing risk of bites and envenoming. Clinical challenges to effective treatment are most substantial in rural areas of low-resource settings, where snakebites are most common. Classic skills of history taking, physical examination, and use of affordable point-of-care tests should be followed by monitoring of evolving local and systemic envenoming. Despite the profusion of new ideas for interventions, hyperimmune equine or ovine plasma-derived antivenoms remain the only specific treatment for snakebite envenoming. The enormous interspecies and intraspecies complexity and diversity of snake venoms, revealed by modern venomics, demands a radical redesign of many current antivenoms.
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Affiliation(s)
- David A Warrell
- Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK; Experimental Medicine Division, John Radcliffe Hospital, Headington, UK.
| | - David J Williams
- Regulation and Prequalification Department, World Health Organization, Geneva, Switzerland
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2
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Brás-Costa C, Chaves AFA, Cajado-Carvalho D, da Silva Pires D, Andrade-Silva D, Serrano SMT. Profilings of subproteomes of lectin-binding proteins of nine Bothrops venoms reveal variability driven by different glycan types. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2022; 1870:140795. [PMID: 35662639 DOI: 10.1016/j.bbapap.2022.140795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 05/23/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
Snake venom proteomes have long been investigated to explore a multitude of biologically active components that are used for prey capture and defense, and are involved in the pathological effects observed upon mammalian envenomation. Glycosylation is a major protein post-translational modification in venoms and contributes to the diversification of proteomes. We have shown that Bothrops venoms are markedly defined by their content of glycoproteins, and that most N-glycan structures of eight Bothrops venoms contain sialic acid, while bisected N-acetylglucosamine was identified in Bothrops cotiara venom. To further investigate the mechanisms involved in the generation of different venoms by related snakes, here the glycoproteomes of nine Bothrops venoms (Bothrops atrox, B. cotiara, Bothrops erythromelas, Bothrops fonsecai, B. insularis, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni and Bothrops neuwiedi) were comparatively analyzed by enrichment with three lectins of different specificities, recognizing bisecting N-acetylglucosamine- and sialic acid-containing glycoproteins, and mass spectrometry. The lectin capture strategy generated venom fractions enriched with several glycoproteins, including metalloprotease, serine protease, and L- amino acid oxidase, in addition to various types of low abundant enzymes. The different contents of lectin-enriched proteins underscore novel aspects of the variability of the glycoprotein subproteomes of Bothrops venoms and point to the role of distinct types of glycan chains in generating different venoms by closely related snake species.
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Affiliation(s)
- Carolina Brás-Costa
- Laboratory of Applied Toxinology, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Alison Felipe Alencar Chaves
- Laboratory of Applied Toxinology, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Daniela Cajado-Carvalho
- Laboratory of Applied Toxinology, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - David da Silva Pires
- Laboratory of Cell Cycle, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Débora Andrade-Silva
- Laboratory of Applied Toxinology, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil
| | - Solange M T Serrano
- Laboratory of Applied Toxinology, Center of Toxins, Immune-Response and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, Brazil.
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3
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Márquez Y, Mantica F, Cozzuto L, Burguera D, Hermoso-Pulido A, Ponomarenko J, Roy SW, Irimia M. ExOrthist: a tool to infer exon orthologies at any evolutionary distance. Genome Biol 2021; 22:239. [PMID: 34416914 PMCID: PMC8379844 DOI: 10.1186/s13059-021-02441-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/26/2021] [Indexed: 12/14/2022] Open
Abstract
Several bioinformatic tools have been developed for genome-wide identification of orthologous and paralogous genes. However, no corresponding tool allows the detection of exon homology relationships. Here, we present ExOrthist, a fully reproducible Nextflow-based software enabling inference of exon homologs and orthogroups, visualization of evolution of exon-intron structures, and assessment of conservation of alternative splicing patterns. ExOrthist evaluates exon sequence conservation and considers the surrounding exon-intron context to derive genome-wide multi-species exon homologies at any evolutionary distance. We demonstrate its use in different evolutionary scenarios: whole genome duplication in frogs and convergence of Nova-regulated splicing networks (https://github.com/biocorecrg/ExOrthist).
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Affiliation(s)
- Yamile Márquez
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain.
| | - Federica Mantica
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain
| | - Luca Cozzuto
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain
| | - Demian Burguera
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain.,Department of Zoology, Charles University, Vinicna 7, 12844, Prague, Czech Republic
| | - Antonio Hermoso-Pulido
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain
| | - Julia Ponomarenko
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain.,Universitat Pompeu Fabra, Barcelona, Spain
| | - Scott W Roy
- San Francisco State University, 1600 Holloway Ave, San Francisco, CA, 94132, USA
| | - Manuel Irimia
- Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Dr. Aiguader, 88, 08003, Barcelona, Spain. .,Universitat Pompeu Fabra, Barcelona, Spain. .,ICREA, Barcelona, Spain.
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4
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Almeida DD, Viala VL, Nachtigall PG, Broe M, Gibbs HL, Serrano SMDT, Moura-da-Silva AM, Ho PL, Nishiyama-Jr MY, Junqueira-de-Azevedo ILM. Tracking the recruitment and evolution of snake toxins using the evolutionary context provided by the Bothrops jararaca genome. Proc Natl Acad Sci U S A 2021; 118:e2015159118. [PMID: 33972420 PMCID: PMC8157943 DOI: 10.1073/pnas.2015159118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Venom is a key adaptive innovation in snakes, and how nonvenom genes were co-opted to become part of the toxin arsenal is a significant evolutionary question. While this process has been investigated through the phylogenetic reconstruction of toxin sequences, evidence provided by the genomic context of toxin genes remains less explored. To investigate the process of toxin recruitment, we sequenced the genome of Bothrops jararaca, a clinically relevant pitviper. In addition to producing a road map with canonical structures of genes encoding 12 toxin families, we inferred most of the ancestral genes for their loci. We found evidence that 1) snake venom metalloproteinases (SVMPs) and phospholipases A2 (PLA2) have expanded in genomic proximity to their nonvenomous ancestors; 2) serine proteinases arose by co-opting a local gene that also gave rise to lizard gilatoxins and then expanded; 3) the bradykinin-potentiating peptides originated from a C-type natriuretic peptide gene backbone; and 4) VEGF-F was co-opted from a PGF-like gene and not from VEGF-A. We evaluated two scenarios for the original recruitment of nontoxin genes for snake venom: 1) in locus ancestral gene duplication and 2) in locus ancestral gene direct co-option. The first explains the origins of two important toxins (SVMP and PLA2), while the second explains the emergence of a greater number of venom components. Overall, our results support the idea of a locally assembled venom arsenal in which the most clinically relevant toxin families expanded through posterior gene duplications, regardless of whether they originated by duplication or gene co-option.
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Affiliation(s)
- Diego Dantas Almeida
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Vincent Louis Viala
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Pedro Gabriel Nachtigall
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Michael Broe
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210
| | - H Lisle Gibbs
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210
| | - Solange Maria de Toledo Serrano
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Ana Maria Moura-da-Silva
- Laboratório de Imunopatologia, Instituto Butantan, São Paulo 05503-900, Brazil
- Programa de Pós-Graduação em Medicina Tropical, Universidade do Estado do Amazonas (UEA), Manaus 69040-000, Brazil
| | - Paulo Lee Ho
- Serviço de Bacteriologia, Divisão BioIndustrial, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Milton Yutaka Nishiyama-Jr
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil
| | - Inácio L M Junqueira-de-Azevedo
- Laboratório de Toxinologia Aplicada, Center of Toxins, Immune-Response and Cell Signaling, Instituto Butantan, São Paulo 05503-900, Brazil;
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5
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Bayona-Serrano JD, Viala VL, Rautsaw RM, Schramer TD, Barros-Carvalho GA, Nishiyama MY, Freitas-de-Sousa LA, Moura-da-Silva AM, Parkinson CL, Grazziotin FG, Junqueira-de-Azevedo ILM. Replacement and Parallel Simplification of Nonhomologous Proteinases Maintain Venom Phenotypes in Rear-Fanged Snakes. Mol Biol Evol 2020; 37:3563-3575. [PMID: 32722789 PMCID: PMC8525196 DOI: 10.1093/molbev/msaa192] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023] Open
Abstract
Novel phenotypes are commonly associated with gene duplications and neofunctionalization, less documented are the cases of phenotypic maintenance through the recruitment of novel genes. Proteolysis is the primary toxic character of many snake venoms, and ADAM metalloproteinases, named snake venom metalloproteinases (SVMPs), are largely recognized as the major effectors of this phenotype. However, by investigating original transcriptomes from 58 species of advanced snakes (Caenophidia) across their phylogeny, we discovered that a different enzyme, matrix metalloproteinase (MMP), is actually the dominant venom component in three tribes (Tachymenini, Xenodontini, and Conophiini) of rear-fanged snakes (Dipsadidae). Proteomic and functional analyses of these venoms further indicate that MMPs are likely playing an "SVMP-like" function in the proteolytic phenotype. A detailed look into the venom-specific sequences revealed a new highly expressed MMP subtype, named snake venom MMP (svMMP), which originated independently on at least three occasions from an endogenous MMP-9. We further show that by losing ancillary noncatalytic domains present in its ancestors, svMMPs followed an evolutionary path toward a simplified structure during their expansion in the genomes, thus paralleling what has been proposed for the evolution of their Viperidae counterparts, the SVMPs. Moreover, we inferred an inverse relationship between the expression of svMMPs and SVMPs along the evolutionary history of Xenodontinae, pointing out that one type of enzyme may be substituting for the other, whereas the general (metallo)proteolytic phenotype is maintained. These results provide rare evidence on how relevant phenotypic traits can be optimized via natural selection on nonhomologous genes, yielding alternate biochemical components.
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Affiliation(s)
| | - Vincent Louis Viala
- Laboratório Especial de Toxinologia Aplicada, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune-Response and Cell Signaling (CeTICS), São Paulo, Brazil
| | - Rhett M Rautsaw
- Department of Biological Sciences, Clemson University, Clemson, SC
| | | | | | - Milton Yutaka Nishiyama
- Laboratório Especial de Toxinologia Aplicada, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune-Response and Cell Signaling (CeTICS), São Paulo, Brazil
| | | | - Ana Maria Moura-da-Silva
- Laboratório de Imunopatologia, Instituto Butantan, São Paulo, Brazil
- Instituto de Pesquisa Clínica Carlos Borborema, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Christopher L Parkinson
- Department of Biological Sciences, Clemson University, Clemson, SC
- Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC
| | | | - Inácio L M Junqueira-de-Azevedo
- Laboratório Especial de Toxinologia Aplicada, Instituto Butantan, São Paulo, Brazil
- Center of Toxins, Immune-Response and Cell Signaling (CeTICS), São Paulo, Brazil
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6
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Calvete JJ, Bonilla F, Granados-Martínez S, Sanz L, Lomonte B, Sasa M. Venomics of the Duvernoy's gland secretion of the false coral snake Rhinobothryum bovallii (Andersson, 1916) and assessment of venom lethality towards synapsid and diapsid animal models. J Proteomics 2020; 225:103882. [DOI: 10.1016/j.jprot.2020.103882] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/16/2020] [Accepted: 06/16/2020] [Indexed: 11/30/2022]
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7
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Olaoba OT, Karina dos Santos P, Selistre-de-Araujo HS, Ferreira de Souza DH. Snake Venom Metalloproteinases (SVMPs): A structure-function update. Toxicon X 2020; 7:100052. [PMID: 32776002 PMCID: PMC7399193 DOI: 10.1016/j.toxcx.2020.100052] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Snake venom metalloproteinases (SVMPs) represent a diverse group of multi-domain proteins with several biological activities such as the ability to induce hemorrhage, proteolytic degradation of fibrinogen and fibrin, induction of apoptosis and inhibition of platelet aggregation. Due to these activities, SVMPs are responsible for many of the well-known pathological phenotypes in snake envenomations caused particularly by species from the Viperidae family and the Crotalinae subfamily. These proteins have been classified based on their size and domain structure into P–I, P-II and P-III classes. Comparatively, members of the P–I SVMPs possess the simplest structures, formed by the catalytic metalloproteinase domain only; the P-II SVMPs are moderately more complex, having the canonical disintegrin domain in addition to the metalloproteinase domain; members of the P-III class are more structurally varied, comprising the metalloproteinase, disintegrin-like, and cysteine-rich domains. Proteolytic cleavage, repeated domain loss and presence of other ancillary domains are responsible for structural diversities in the P-III class. However, studies continue to unveil the relationship between the structure and function of these proteins. In this review, we recovered evidences from literature on the structural peculiarities and functional classification of Snake Venom Metalloproteinases. In addition, we reflect on diversities that exist among each class while taking into account specific and up-to-date class-based activities.
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Affiliation(s)
- Olamide Tosin Olaoba
- Departamento de Química, Universidade Federal de São Carlos, Rodovia Washington Luís, Km 235, São Carlos, São Paulo, Brazil
| | - Patty Karina dos Santos
- Departamento de Ciências Fisiológicas, Universidade Federal de São Carlos, Rodovia Washington Luís, Km 235, São Carlos, São Paulo, Brazil
| | | | - Dulce Helena Ferreira de Souza
- Departamento de Química, Universidade Federal de São Carlos, Rodovia Washington Luís, Km 235, São Carlos, São Paulo, Brazil
- Corresponding author.
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8
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Abstract
The genetic origins of novelty are a central interest of evolutionary biology. Most new proteins evolve from preexisting proteins but the evolutionary path from ancestral gene to novel protein is challenging to trace, and therefore the requirements for and order of coding sequence changes, expression changes, or gene duplication are not clear. Snake venoms are important novel traits that are comprised of toxins derived from several distinct protein families, but the genomic and evolutionary origins of most venom components are not understood. Here, we have traced the origin and diversification of one prominent family, the snake venom metalloproteinases (SVMPs) that play key roles in subduing prey in many vipers. Genomic analyses of several rattlesnake (Crotalus) species revealed the SVMP family massively expanded from a single, deeply conserved adam28 disintegrin and metalloproteinase gene, to as many as 31 tandem genes in the Western Diamondback rattlesnake (Crotalus atrox) through a number of single gene and multigene duplication events. Furthermore, we identified a series of stepwise intragenic deletions that occurred at different times in the course of gene family expansion and gave rise to the three major classes of secreted SVMP toxins by sequential removal of a membrane-tethering domain, the cysteine-rich domain, and a disintegrin domain, respectively. Finally, we show that gene deletion has further shaped the SVMP complex within rattlesnakes, creating both fusion genes and substantially reduced gene complexes. These results indicate that gene duplication and intragenic deletion played essential roles in the origin and diversification of these novel biochemical weapons.
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9
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Beta-defensin genes of the Colubridae snakes Phalotris mertensi , Thamnodynastes hypoconia , and T. strigatus. Toxicon 2018; 146:124-128. [DOI: 10.1016/j.toxicon.2018.02.048] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 02/22/2018] [Accepted: 02/26/2018] [Indexed: 01/16/2023]
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10
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Andrade-Silva D, Ashline D, Tran T, Lopes AS, Travaglia Cardoso SR, Reis MDS, Zelanis A, Serrano SMT, Reinhold V. Structures of N-Glycans of Bothrops Venoms Revealed as Molecular Signatures that Contribute to Venom Phenotype in Viperid Snakes. Mol Cell Proteomics 2018; 17:1261-1284. [PMID: 29716988 DOI: 10.1074/mcp.ra118.000748] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/26/2018] [Indexed: 11/06/2022] Open
Abstract
The complexity of snake venoms has long been investigated to explore a myriad of biologically active proteins and peptides that are used for immobilizing or killing prey, and are responsible for the pathological effects observed on envenomation. Glycosylation is the main post-translational modification (PTM) of viperid venoms but currently there is little understanding of how protein glycosylation impacts the variation of venom proteomes. We have previously reported that Bothrops venom glycoproteomes contain a core of components that markedly define their composition and parallel their phylogenetic classification. Here we extend those observations to eight Bothrops species evaluating the N-glycomes by LC-MS as assigned cartoon structures and detailing those structures separately as methylated analogs using ion-trap mass spectrometry (MSn). Following ion disassembly through multiple steps provided sequence and linkage isomeric details that characterized 52 unique compositions in Bothrops venoms. These occurred as 60 structures, of which 26 were identified in the venoms of the Jararaca Complex (B. alcatraz, B. insularis, and B. jararaca), 20 in B. erythromelas, B. jararacussu, B. moojeni and B. neuwiedi venoms, and 22 in B. cotiara venom. Further, quantitative analysis of these N-glycans showed variable relative abundances in the venoms. For the first time a comprehensive set of N-glycan structures present in snake venoms are defined. Despite the fact that glycosylation is not template-defined, the N-glycomes of these venoms mirror the phylogeny cladograms of South American bothropoid snakes reported in studies on morphological, molecular data and feeding habits, exhibiting distinct molecular signatures for each venom. Considering the complexity of N-glycan moieties generally found in glycoproteins, characterized by different degrees of branching, isomer structures, and variable abundances, our findings point to these factors as another level of complexity in Bothrops venoms, features that could dramatically contribute to their distinct biological activities.
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Affiliation(s)
| | - David Ashline
- §The Glycomics Center, University of New Hampshire, Durham, NH 03824
| | - Thuy Tran
- §The Glycomics Center, University of New Hampshire, Durham, NH 03824
| | - Aline Soriano Lopes
- ‖Departamento de Química, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Diadema, 09913-030 Brazil
| | | | - Marcelo da Silva Reis
- ¶Laboratório Especial de Ciclo Celular, Center of Toxins, Immune-Response, and Cell Signaling (CeTICS), Instituto Butantan, São Paulo, 05503-900, Brazil
| | - André Zelanis
- ‡‡Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo (ICT-UNIFESP), São José dos Campos, 12231-280, Brazil
| | | | - Vernon Reinhold
- §The Glycomics Center, University of New Hampshire, Durham, NH 03824;
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11
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Kini RM. Accelerated evolution of toxin genes: Exonization and intronization in snake venom disintegrin/metalloprotease genes. Toxicon 2018; 148:16-25. [PMID: 29634956 DOI: 10.1016/j.toxicon.2018.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/21/2018] [Accepted: 04/01/2018] [Indexed: 12/20/2022]
Abstract
Toxin genes in animals undergo accelerated evolution compared to non-toxin genes to be effective and competitive in prey capture, as well as to enhance their predator defense. Several mechanisms have been proposed to explain this unusual phenomenon. These include (a) frequent mutations in exons compared to introns and nonsynonymous substitutions in exons; (b) high frequency of point mutations are due to the presence of more unstable triplets in exons compared to introns; (c) Accelerated Segment Switch in Exons to alter Targeting (ASSET); (d) Rapid Accumulation of Variations in Exposed Residues (RAVERs); (e) alteration in intron-exon boundary; (f) deletion of exon; and (g) loss/gain of domains through recombination. By systematic analyses of snake venom disintegrin/metalloprotease genes, I describe a new mechanism in the evolution of these genes through exonization and intronization. In the evolution of RTS/KTS disintegrins, a new exon (10a) is formed in intron 10 of the disintegrin/metalloprotease gene. Unlike more than 90% new exons that are from repetitive elements in introns, exon 10a originated from a non-repetitive element. To incorporate exon 10a, part of the exon 11 is intronized to retain the open reading frame. This is the first case of simultaneous exonization and intronization within a single gene. This new mechanism alters the function of toxins through drastic changes to the molecular surface via insertion of new exons and deletion of exons.
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Affiliation(s)
- R Manjunatha Kini
- Protein Science Laboratory, Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.
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12
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Abstract
Snakebite envenoming is a neglected tropical disease that kills >100,000 people and maims >400,000 people every year. Impoverished populations living in the rural tropics are particularly vulnerable; snakebite envenoming perpetuates the cycle of poverty. Snake venoms are complex mixtures of proteins that exert a wide range of toxic actions. The high variability in snake venom composition is responsible for the various clinical manifestations in envenomings, ranging from local tissue damage to potentially life-threatening systemic effects. Intravenous administration of antivenom is the only specific treatment to counteract envenoming. Analgesics, ventilator support, fluid therapy, haemodialysis and antibiotic therapy are also used. Novel therapeutic alternatives based on recombinant antibody technologies and new toxin inhibitors are being explored. Confronting snakebite envenoming at a global level demands the implementation of an integrated intervention strategy involving the WHO, the research community, antivenom manufacturers, regulatory agencies, national and regional health authorities, professional health organizations, international funding agencies, advocacy groups and civil society institutions.
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Affiliation(s)
- José María Gutiérrez
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, PO Box 11501-2060, San José, Costa Rica
| | - Juan J Calvete
- Instituto de Biomedicina de Valencia, Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain
| | | | - Robert A Harrison
- Alistair Reid Venom Research Unit, Liverpool School of Tropical Medicine, Liverpool, UK
| | - David J Williams
- Charles Campbell Toxinology Centre, School of Medicine &Health Sciences, University of Papua New Guinea, Boroko, National Capital District, Papua New Guinea
- Australian Venom Research Unit, Department of Pharmacology and Therapeutics, University of Melbourne, Parkville, Victoria, Australia
| | - David A Warrell
- Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK
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13
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Venomics: integrative venom proteomics and beyond*. Biochem J 2017; 474:611-634. [DOI: 10.1042/bcj20160577] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 12/31/2016] [Accepted: 01/03/2017] [Indexed: 01/15/2023]
Abstract
Venoms are integrated phenotypes that evolved independently in, and are used for predatory and defensive purposes by, a wide phylogenetic range of organisms. The same principles that contribute to the evolutionary success of venoms, contribute to making the study of venoms of great interest in such diverse fields as evolutionary ecology and biotechnology. Evolution is profoundly contingent, and nature also reinvents itself continuosly. Changes in a complex phenotypic trait, such as venom, reflect the influences of prior evolutionary history, chance events, and selection. Reconstructing the natural history of venoms, particularly those of snakes, which will be dealt with in more detail in this review, requires the integration of different levels of knowledge into a meaningful and comprehensive evolutionary framework for separating stochastic changes from adaptive evolution. The application of omics technologies and other disciplines have contributed to a qualitative and quantitative advance in the road map towards this goal. In this review we will make a foray into the world of animal venoms, discuss synergies and complementarities of the different approaches used in their study, and identify current bottlenecks that prevent inferring the evolutionary mechanisms and ecological constraints that molded snake venoms to their present-day variability landscape.
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14
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Snake Genome Sequencing: Results and Future Prospects. Toxins (Basel) 2016; 8:toxins8120360. [PMID: 27916957 PMCID: PMC5198554 DOI: 10.3390/toxins8120360] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 12/16/2022] Open
Abstract
Snake genome sequencing is in its infancy—very much behind the progress made in sequencing the genomes of humans, model organisms and pathogens relevant to biomedical research, and agricultural species. We provide here an overview of some of the snake genome projects in progress, and discuss the biological findings, with special emphasis on toxinology, from the small number of draft snake genomes already published. We discuss the future of snake genomics, pointing out that new sequencing technologies will help overcome the problem of repetitive sequences in assembling snake genomes. Genome sequences are also likely to be valuable in examining the clustering of toxin genes on the chromosomes, in designing recombinant antivenoms and in studying the epigenetic regulation of toxin gene expression.
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