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Silva-Magalhães R, Silva-Araújo AL, Peres-Damásio P, Teixeira Pereira EH, de Oliveira Souza R, Varela LSDRN, Tomé LMR, de Melo Iani FC, Silveira AL, Borges MH, Medina-Santos R, Chavez-Olórtegui C, Vasconcelos Diniz MR, Paiva ALB, Guerra-Duarte C. Loxosceles amazonica Brown Spider venom: Insights into enzymatic activities, immunorecognition, and novel phospholipase D isoforms. Biochimie 2024:S0300-9084(24)00156-1. [PMID: 38944106 DOI: 10.1016/j.biochi.2024.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/04/2024] [Accepted: 06/26/2024] [Indexed: 07/01/2024]
Abstract
The Loxosceles genus represents one of the main arachnid genera of medical importance in Brazil. Despite the gravity of Loxosceles-related accidents, just a handful of species are deemed medically important and only a few have undergone comprehensive venom characterization. Loxosceles amazonica is a notable example of a potentially dangerous yet understudied Loxosceles species. While there have been limited reports of accidents involving L. amazonica to date, accidents related to Loxosceles are increasing in the North and Northeast regions of Brazil, where L. amazonica has been reported. In this work, we provide a complementary biochemical and immunological characterization of L. amazonica venom, considering its most relevant enzymatic activities and its immunorecognition and neutralization by current therapeutic antivenoms. Additionally, a cDNA library enriched with phospholipase D (PLD) sequences from L. amazonica venom glands was built and subsequently sequenced. The results showed that L. amazonica venom is well immunorecognised by all the tested antibodies. Its venom also displayed proteolytic, hyaluronidase, and sphingomyelinase activities. These activities were at least partially inhibited by available antivenoms. With cDNA sequencing of PLDs, seven new putative isoforms were identified in the venom of L. amazonica. These results contribute to a better knowledge of the venom content and activities of a synanthropic, yet understudied, Loxosceles species. In vivo assays are essential to confirm the medical relevance of L. amazonica, as well as to assess its true toxic potential and elucidate its related pathophysiology.
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Affiliation(s)
- Rafaela Silva-Magalhães
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil; Biochemistry and Immunology Department, Biological Sciences Institute, Federal University of Minas Gerais - UFMG, Belo Horizonte, MG, Brazil
| | - Ana Luiza Silva-Araújo
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | - Pamella Peres-Damásio
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | | | - Ramon de Oliveira Souza
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | | | - Luiz Marcelo Ribeiro Tomé
- Central Laboratory of Public Health of Minas Gerais, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | - Felipe Campos de Melo Iani
- Central Laboratory of Public Health of Minas Gerais, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | | | - Márcia Helena Borges
- Arachnid Proteomics Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | - Raíssa Medina-Santos
- Biochemistry and Immunology Department, Biological Sciences Institute, Federal University of Minas Gerais - UFMG, Belo Horizonte, MG, Brazil
| | - Carlos Chavez-Olórtegui
- Biochemistry and Immunology Department, Biological Sciences Institute, Federal University of Minas Gerais - UFMG, Belo Horizonte, MG, Brazil
| | | | - Ana Luiza Bittencourt Paiva
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil
| | - Clara Guerra-Duarte
- Molecular Toxinology Lab, Research and Development Department, Ezequiel Dias Foundation - Funed, Belo Horizonte, MG, Brazil.
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Lopes PH, Fukushima CS, Shoji R, Bertani R, Tambourgi DV. Searching for the toxic potential of Loxosceles amazonica and Loxosceles willianilsoni spiders' venoms. Toxicon 2020; 191:1-8. [PMID: 33347860 DOI: 10.1016/j.toxicon.2020.12.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 11/25/2020] [Accepted: 12/13/2020] [Indexed: 11/16/2022]
Abstract
The Loxosceles genus belongs to the Sicariidae family and it comprises species whose venom can cause accidents with potentially fatal consequences. We have previously shown that SMase D is the enzyme responsible for the main pathological effects of Loxosceles venom. Despite the severity of accidents with Loxosceles, few species are considered to be of medical importance. Little is known about the venom of non-synanthropic species that live in natural environments. To contribute to a better understanding about the venom's toxicity of Loxosceles genus, the aim of this study was to (i) characterize the toxic properties of Loxosceles amazonica from two different localities and a recent described cave species Loxosceles willianilsoni and (ii) compare these venoms with that from Loxosceles laeta, which is among the most toxic ones. We show here that both L. amazonica venoms (from the two studied locations) and L. willianilsoni presented SMase D activity similar to that exhibited by L. laeta venom. Although L. amazonica and L. willianilsoni venoms were able to induce complement dependent human erythrocytes lysis, they were not able to induce cell death of human keratinocytes, as promoted by L. laeta venom, in the concentrations tested. These results indicate that other species of Loxosceles, in addition to those classified as medically important, have toxic potential to cause accidents in humans, despite interspecific variations that denote possible less toxicity.
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Affiliation(s)
| | - Caroline Sayuri Fukushima
- Special Laboratory of Ecology and Evolution, Butantan Institute, São Paulo, Brazil; Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - Rosana Shoji
- Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil
| | - Rogério Bertani
- Special Laboratory of Ecology and Evolution, Butantan Institute, São Paulo, Brazil
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3
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Lopes PH, Squaiella-Baptistão CC, Marques MOT, Tambourgi DV. Clinical aspects, diagnosis and management of Loxosceles spider envenomation: literature and case review. Arch Toxicol 2020; 94:1461-1477. [PMID: 32232511 DOI: 10.1007/s00204-020-02719-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/12/2020] [Indexed: 01/10/2023]
Abstract
The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.
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Affiliation(s)
- Priscila Hess Lopes
- Laboratório de Imunoquímica, Instituto Butantan, Av. Vital Brazil, 1500, São Paulo, SP, 05503-900, Brazil
| | | | | | - Denise V Tambourgi
- Laboratório de Imunoquímica, Instituto Butantan, Av. Vital Brazil, 1500, São Paulo, SP, 05503-900, Brazil.
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4
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Gremski LH, da Justa HC, da Silva TP, Polli NLC, Antunes BC, Minozzo JC, Wille ACM, Senff-Ribeiro A, Arni RK, Veiga SS. Forty Years of the Description of Brown Spider Venom Phospholipases-D. Toxins (Basel) 2020; 12:toxins12030164. [PMID: 32155765 PMCID: PMC7150852 DOI: 10.3390/toxins12030164] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 02/28/2020] [Accepted: 03/02/2020] [Indexed: 01/24/2023] Open
Abstract
Spiders of the genus Loxosceles, popularly known as Brown spiders, are considered a serious public health issue, especially in regions of hot or temperate climates, such as parts of North and South America. Although the venoms of these arachnids are complex in molecular composition, often containing proteins with distinct biochemical characteristics, the literature has primarily described a family of toxins, the Phospholipases-D (PLDs), which are highly conserved in all Loxosceles species. PLDs trigger most of the major clinical symptoms of loxoscelism i.e., dermonecrosis, thrombocytopenia, hemolysis, and acute renal failure. The key role played by PLDs in the symptomatology of loxoscelism was first described 40 years ago, when researches purified a hemolytic toxin that cleaved sphingomyelin and generated choline, and was referred to as a Sphingomyelinase-D, which was subsequently changed to Phospholipase-D when it was demonstrated that the enzyme also cleaved other cellular phospholipids. In this review, we present the information gleaned over the last 40 years about PLDs from Loxosceles venoms especially with regard to the production and characterization of recombinant isoforms. The history of obtaining these toxins is discussed, as well as their molecular organization and mechanisms of interaction with their substrates. We will address cellular biology aspects of these toxins and how they can be used in the development of drugs to address inflammatory processes and loxoscelism. Present and future aspects of loxoscelism diagnosis will be discussed, as well as their biotechnological applications and actions expected for the future in this field.
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Affiliation(s)
- Luiza Helena Gremski
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
| | - Hanna Câmara da Justa
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
| | - Thaís Pereira da Silva
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
| | - Nayanne Louise Costacurta Polli
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
| | - Bruno César Antunes
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
- Centro de Produção e Pesquisa de Imunobiológicos (CPPI), Piraquara 83302-200, PR, Brazil;
| | - João Carlos Minozzo
- Centro de Produção e Pesquisa de Imunobiológicos (CPPI), Piraquara 83302-200, PR, Brazil;
| | - Ana Carolina Martins Wille
- Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa, Ponta Grossa 84030-900, PR, Brazil;
| | - Andrea Senff-Ribeiro
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
| | - Raghuvir Krishnaswamy Arni
- Centro Multiusuário de Inovação Biomolecular, Departamento de Física, Universidade Estadual Paulista (UNESP), São José do Rio Preto 15054-000, SP, Brazil;
| | - Silvio Sanches Veiga
- Departamento de Biologia Celular, Universidade Federal do Paraná (UFPR), Curitiba 81531-980, PR, Brazil; (L.H.G.); (H.C.d.J.); (T.P.d.S.); (N.L.C.P.); (B.C.A.); (A.S.-R.)
- Correspondence: ; Tel.: +55-(41)-3361-1776
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From taxonomy to molecular characterization of brown spider venom: An overview focused on Loxosceles similis. Toxicon 2020; 173:5-19. [DOI: 10.1016/j.toxicon.2019.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/31/2019] [Accepted: 11/11/2019] [Indexed: 11/22/2022]
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6
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Spider's venom phospholipases D: A structural review. Int J Biol Macromol 2017; 107:1054-1065. [PMID: 28951301 DOI: 10.1016/j.ijbiomac.2017.09.081] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/25/2017] [Accepted: 09/20/2017] [Indexed: 12/28/2022]
Abstract
Spider venoms are complex mixtures of proteins, peptides and small organic and inorganic molecules. Among the proteins, phospholipases D (PLDs) present the major portion, and till now they are the most studied enzymes in spider venom. These PLDs have been divided into two classes, I and II, based on their primary and tertiary structure. Currently, crystal structures of both classes of these enzymes are available in the Protein Data Bank (PDB). Their three-dimensional structure is composed of eight α-helices and eight β-strands forming the ubiquitous fold called triosephosphate isomerase (TIM) barrel. These enzymes use general acid-base catalysis to hydrolyzes their substrate. In this review, we have described the structural features, structure-based mechanisms of catalysis, maturation, and inhibition of these enzymes using the synthetic inhibitor.
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Not as docile as it looks? Loxosceles venom variation and loxoscelism in the Mediterranean Basin and the Canary Islands. Toxicon 2014; 93:11-9. [PMID: 25449105 DOI: 10.1016/j.toxicon.2014.10.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/23/2014] [Accepted: 10/01/2014] [Indexed: 01/26/2023]
Abstract
The medical importance of Loxosceles spiders has promoted extensive research on different aspects of their venoms. Most of the reported cases of loxoscelism have occurred in the Americas, and thus, much work has focused on North and South American Loxosceles species. Interestingly, loxoscelism cases are rare in the Mediterranean Basin although Loxosceles rufescens, endemic to the Mediterranean, is an abundant spider even in human-altered areas. Thus, it has been suggested that the venom of L. rufescens could be of less medical relevance than that of its congeners. In this study, we challenge this hypothesis by using multiple approaches to study venom variation in selected species and lineages from the Mediterranean Basin and the Canary Islands. We found that SMase D activity, the key bioactive component of Loxosceles venom, is comparable to American species that are confirmed to have medically relevant bites. The venom protein composition using SDS-PAGE presents some differences among regional Loxosceles taxa in banding pattern and intensity, mostly between the Canarian and L. rufescens lineages. Differences between these species also exist in the expression of different paralogs of the SicTox gene family, with the Canarian species being less diverse. In conclusion, our results do not support the challenged hypothesis, and suggest that venom of these species may indeed be as potent as other Loxosceles species. Pending confirmation of loxoscelism with direct evidence of Loxosceles bites with species identification by professionals, Loxosceles in the Mediterranean region should conservatively be considered medically relevant taxa.
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8
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Recent advances in the understanding of brown spider venoms: From the biology of spiders to the molecular mechanisms of toxins. Toxicon 2014; 83:91-120. [DOI: 10.1016/j.toxicon.2014.02.023] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 12/19/2013] [Accepted: 02/27/2014] [Indexed: 11/22/2022]
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Zobel-Thropp PA, Correa SM, Garb JE, Binford GJ. Spit and venom from scytodes spiders: a diverse and distinct cocktail. J Proteome Res 2013; 13:817-35. [PMID: 24303891 DOI: 10.1021/pr400875s] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spiders from the family Scytodidae have a unique prey capturing technique: they spit a zig-zagged silken glue to tether prey to a surface. Effectiveness of this sticky mixture is based on a combination of contraction and adhesion, trapping prey until the spider immobilizes it by envenomation and then feeds. We identify components expressed in Scytodes thoracica venom glands using combined transcriptomic and proteomic analyses. These include homologues of toxic proteins astacin metalloproteases and potentially toxic proteins including venom allergen, longistatin, and translationally controlled tumor protein (TCTP). We classify 19 distinct groups of candidate peptide toxins; 13 of these were detected in the venom, making up 35% of the proteome. Six have significant similarity to toxins from spider species spanning mygalomorph and nonhaplogyne araneomorph lineages, suggesting their expression in venom is phylogenetically widespread. Twelve peptide toxin groups have homologues in venom gland transcriptomes of other haplogynes. Of the transcripts, approximately 50% encode glycine-rich peptides that may contribute to sticky fibers in Scytodes spit. Fifty-one percent of the identified venom proteome is a family of proteins that is homologous to sequences from Drosophila sp. and Latrodectus hesperus with uncharacterized function. Characterization of these components holds promise for discovering new functional activity.
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Affiliation(s)
- Pamela A Zobel-Thropp
- Department of Biology, Lewis & Clark College , Portland, Oregon 97219, United States
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10
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Biochemical and immunological characteristics of Peruvian Loxosceles laeta spider venom: neutralization of its toxic effects by anti-loxoscelic antivenoms. Toxicon 2013; 70:90-7. [PMID: 23648420 DOI: 10.1016/j.toxicon.2013.04.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Revised: 04/16/2013] [Accepted: 04/18/2013] [Indexed: 11/21/2022]
Abstract
This manuscript describes the general biochemical properties and immunological characteristics of Peruvian spider Loxosceles laeta venom (PLlv), which is responsible for the largest number of accidents involving venomous animals in Peru. In this work, we observed that the venom of this spider is more lethal to mice when compared with L. laeta venom from Brazil (BLlv). The LD₅₀ of PLlv was 1.213 mg/kg when the venom was intradermally injected. The venom displayed sphingomyelinase activity and produced dermonecrotic, hemorrhagic and edema effects in rabbits. 2-D SDS-PAGE separation of the soluble venoms resulted in a protein profile ranging from 20 to 205 kDa. Anti-PLlv and anti-BLlv sera produced in rabbits and assayed by ELISA showed that rabbit antibodies cross-reacted with PLlv and BLlv and also with other Brazilian Loxosceles venoms. Western blotting analysis showed that bands corresponding to 25-35 kDa are the proteins best recognized in every Loxosceles spp venoms analyzed. The immunized rabbits displayed protective effect after challenge with PLlv and BLlv. In vitro assays with horse anti-loxoscelic antivenoms produced in Brazil and Peru demonstrated that these commercial antivenoms were efficient to inhibit the sphingomyelinase activity of PLlv and BLlv.
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11
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Sphingomyelinase D in sicariid spider venom is a potent insecticidal toxin. Toxicon 2012; 60:265-71. [PMID: 22561243 DOI: 10.1016/j.toxicon.2012.04.350] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 04/17/2012] [Accepted: 04/24/2012] [Indexed: 02/06/2023]
Abstract
Spider venoms have evolved over hundreds of millions of years with a primary role of immobilizing prey. Sphingomyelinase D (SMase D) and homologs in the SicTox gene family are the most abundantly expressed toxic protein in venoms of Loxosceles and Sicarius spiders (Sicariidae). While SMase D is well known to cause dermonecrotic lesions in mammals, little work has investigated the bioactivity of this enzyme in its presumed natural role of immobilizing insect prey. We expressed and purified recombinant SMase D from Loxosceles arizonica (Laz-SMase D) and compared its enzymatic and insecticidal activity to that of crude venom. SMase D enzymatic activities of purified protein and crude venom from the same species were indistinguishable. In addition, SMase D and crude venom have comparable and high potency in immobilization assays on crickets. These data indicate that SMase D is a potent insecticidal toxin, the role for which it presumably evolved.
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12
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Tambourgi DV, Gonçalves-de-Andrade RM, van den Berg CW. Loxoscelism: From basic research to the proposal of new therapies. Toxicon 2010; 56:1113-9. [DOI: 10.1016/j.toxicon.2010.01.021] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 01/26/2010] [Accepted: 01/29/2010] [Indexed: 11/27/2022]
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Zobel-Thropp PA, Bodner MR, Binford GJ. Comparative analyses of venoms from American and African Sicarius spiders that differ in sphingomyelinase D activity. Toxicon 2010; 55:1274-82. [DOI: 10.1016/j.toxicon.2010.01.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 01/14/2010] [Accepted: 01/27/2010] [Indexed: 10/19/2022]
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14
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Binford GJ, Bodner MR, Cordes MHJ, Baldwin KL, Rynerson MR, Burns SN, Zobel-Thropp PA. Molecular evolution, functional variation, and proposed nomenclature of the gene family that includes sphingomyelinase D in sicariid spider venoms. Mol Biol Evol 2008; 26:547-66. [PMID: 19042943 DOI: 10.1093/molbev/msn274] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The venom enzyme sphingomyelinase D (SMase D) in the spider family Sicariidae (brown or fiddleback spiders [Loxosceles] and six-eyed sand spiders [Sicarius]) causes dermonecrosis in mammals. SMase D is in a gene family with multiple venom-expressed members that vary in functional specificity. We analyze molecular evolution of this family and variation in SMase D activity among crude venoms using a data set that represents the phylogenetic breadth of Loxosceles and Sicarius. We isolated a total of 190 nonredundant nucleotide sequences encoding 168 nonredundant amino acid sequences of SMase D homologs from 21 species. Bayesian phylogenies support two major clades that we name alpha and beta, within which we define seven and three subclades, respectively. Sequences in the alpha clade are exclusively from New World Loxosceles and Loxosceles rufescens and include published genes for which expression products have SMase D and dermonecrotic activity. The beta clade includes paralogs from New World Loxosceles that have no, or reduced, SMase D and no dermonecrotic activity and also paralogs from Sicarius and African Loxosceles of unknown activity. Gene duplications are frequent, consistent with a birth-and-death model, and there is evidence of purifying selection with episodic positive directional selection. Despite having venom-expressed SMase D homologs, venoms from New World Sicarius have reduced, or no, detectable SMase D activity, and Loxosceles in the Southern African spinulosa group have low SMase D activity. Sequence conservation mapping shows >98% conservation of proposed catalytic residues of the active site and around a plug motif at the opposite end of the TIM barrel, but alpha and beta clades differ in conservation of key residues surrounding the apparent substrate binding pocket. Based on these combined results, we propose an inclusive nomenclature for the gene family, renaming it SicTox, and discuss emerging patterns of functional diversification.
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Affiliation(s)
- Greta J Binford
- Department of Biology, Lewis and Clark College, Portland, OR, USA.
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15
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Kalapothakis E, Chatzaki M, Gonçalves-Dornelas H, de Castro CS, Silvestre FG, Laborne FV, de Moura JF, Veiga SS, Chávez-Olórtegui C, Granier C, Barbaro KC. The Loxtox protein family in Loxosceles intermedia (Mello-Leitão) venom. Toxicon 2007; 50:938-46. [PMID: 17825864 DOI: 10.1016/j.toxicon.2007.07.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 07/02/2007] [Accepted: 07/03/2007] [Indexed: 11/23/2022]
Abstract
We isolated cDNA sequences coding for dermonecrotic/sphingomyelinases factor proteins from the brown spider Loxosceles intermedia, here named Loxtox proteins. The amino acid sequences based on cloned cDNA of several Loxtox proteins revealed at least six distinct groups of proteins expressed in the venom gland. The level of similarity among the toxins varied from 99% to 55%. The finding of several isoforms of Loxtox in the venom of this spider may reflect an evolutionary adaptation for different prey types and reinforces the idea of an efficient mutational mechanism in the venom gland of spiders.
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Affiliation(s)
- E Kalapothakis
- Departamento de Biologia Geral Instituto de Ciências Biológicas; Universidade Federal de Minas Gerais, CEP 31270901 Belo Horizonte, MG, Brazil.
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16
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Silvestre FG, de Castro CS, de Moura JF, Giusta MS, De Maria M, Alvares ESS, Lobato FCF, Assis RA, Gonçalves LA, Gubert IC, Chávez-Olórtegui C, Kalapothakis E. Characterization of the venom from the Brazilian Brown Spider Loxosceles similis Moenkhaus, 1898 (Araneae, Sicariidae). Toxicon 2005; 46:927-36. [PMID: 16289643 DOI: 10.1016/j.toxicon.2005.09.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 09/14/2005] [Accepted: 09/22/2005] [Indexed: 11/29/2022]
Abstract
Accidents caused by brown spiders (Loxosceles genus) are frequent in Brazil and are associated with dermonecrotic lesions and, eventually, systemic reactions that may be lethal. The major species implicated with human envenoming have been: L. intermedia, L. gaucho and L. laeta. In this study we characterized the venom from Loxosceles similis, a species of spider normally found inside caves. L. similis venom was characterized by two-dimensional gel electrophoresis and enzymatic activity (dermonecrosis and haemolysis). The lethal dose to mice and the capacity of commercial anti-serum to neutralize this venom were also analysed. The cross-reactivity with anti-venoms against L. intermedia, L. laeta and L. gaucho were studied. Our results showed that this venom was able to induce severe dermonecrotic lesions and showed the presence of the bacteria Clostridium septicum in association with the fangs. In addition, we have cloned the DNA coding for a dermonecrotic protein (LsD1), using the genomic DNA of L. similis. The deduced amino acid sequence showed a toxin of approximately 31.2 kDa with an estimated pI of 7.37 and sequence similar to LiD1, a protein from the dermonecrotic family of Loxosceles intermedia spider venom, a synanthropic species of medical importance.
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Affiliation(s)
- F G Silvestre
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, ICB, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, CEP 31270901, Brazil
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