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Trento MVC, Sales TA, de Abreu TS, Braga MA, Cesar PHS, Marques TR, Marcussi S. Exploring the structural and functional aspects of the phospholipase A 2 from Naja spp. Int J Biol Macromol 2019; 140:49-58. [PMID: 31421173 DOI: 10.1016/j.ijbiomac.2019.08.125] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 01/22/2023]
Abstract
Naja spp. venom is a natural source of active compounds with therapeutic application potential. Phospholipase A2 (PLA2) is abundant in the venom of Naja spp. and can perform neurotoxicity, cytotoxicity, cardiotoxicity, and hematological disorders. The PLA2s from Naja spp. venoms are Asp 49 isoenzymes with the exception of PLA2 Cys 49 from Naja sagittifera. When looking at the functional aspects, the neurotoxicity occurs by PLA2 called β-toxins that have affinity for phosphatidylcholine in nerve endings and synaptosomes membranes, and by α-toxins that block the nicotinic acetylcholine receptors in the neuromuscular junctions. In addition, these neurotoxins may inhibit K+ and Ca++ channels or even interfere with the Na+/K+/ATPase enzyme. The disturbance in the membrane fluidity also results in inhibition of the release of acetylcholine. The PLA2 can act as anticoagulants or procoagulant. The cytotoxicity exerted by PLA2s result from changes in the cardiomyocyte membranes, triggering cardiac failure and hemolysis. The antibacterial activity, however, is the result of alterations that decrease the stability of the lipid bilayer. Thus, the understanding of the structural and functional aspects of PLA2s can contribute to studies on the toxic and therapeutic mechanisms involved in the envenomation by Naja spp. and in the treatment of pathologies.
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Affiliation(s)
- Marcus Vinícius Cardoso Trento
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil.
| | - Thais Aparecida Sales
- Computational Chemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Tatiane Silva de Abreu
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Mariana Aparecida Braga
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Pedro Henrique Souza Cesar
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Tamara Rezende Marques
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
| | - Silvana Marcussi
- Biochemistry Laboratory, Department of Chemistry, Universidade Federal de Lavras (UFLA), Lavras, Minas Gerais 37200-000, Brazil
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Sanz L, de Freitas-Lima LN, Quesada-Bernat S, Graça-de-Souza VK, Soares AM, Calderón LDA, Calvete JJ, Caldeira CA. Comparative venomics of Brazilian coral snakes: Micrurus frontalis, Micrurus spixii spixii, and Micrurus surinamensis. Toxicon 2019; 166:39-45. [DOI: 10.1016/j.toxicon.2019.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/23/2019] [Accepted: 05/08/2019] [Indexed: 12/12/2022]
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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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Casais-E-Silva LL, Teixeira CFP, Lebrun I, Lomonte B, Alape-Girón A, Gutiérrez JM. Lemnitoxin, the major component of Micrurus lemniscatus coral snake venom, is a myotoxic and pro-inflammatory phospholipase A2. Toxicol Lett 2016; 257:60-71. [PMID: 27282409 DOI: 10.1016/j.toxlet.2016.06.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2016] [Revised: 05/14/2016] [Accepted: 06/04/2016] [Indexed: 12/28/2022]
Abstract
The venom of Micrurus lemniscatus, a coral snake of wide geographical distribution in South America, was fractionated by reverse-phase HPLC and the fractions screened for phospholipase A2 (PLA2) activity. The major component of the venom, a PLA2, here referred to as 'Lemnitoxin', was isolated and characterized biochemically and toxicologically. It induces myotoxicity upon intramuscular or intravenous injection into mice. The amino acid residues Arg15, Ala100, Asn108, and a hydrophobic residue at position 109, which are characteristic of myotoxic class I phospholipases A2, are present in Lemnitoxin. This PLA2 is antigenically related to M. nigrocinctus nigroxin, Notechis scutatus notexin, Pseudechis australis mulgotoxin, and Pseudonaja textilis textilotoxin, as demonstrated with monoclonal and polyclonal antibodies. Lemnitoxin is highly selective in its targeting of cells, being cytotoxic for differentiated myotubes in vitro and muscle fibers in vivo, but not for undifferentiated myoblasts or endothelial cells. Lemnitoxin is not lethal after intravenous injection at doses up to 2μg/g in mice, evidencing its lack of significant neurotoxicity. Lemnitoxin displays anticoagulant effect on human plasma and proinflammatory activity also, as it induces paw edema and mast cell degranulation. Thus, the results of this work demonstrate that Lemnitoxin is a potent myotoxic and proinflammatory class I PLA2.
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Affiliation(s)
- Luciana L Casais-E-Silva
- Laboratory of Neuroimmunoendocrinology and Toxinology, Department of Bioregulation, Institute of Health Sciences (ICS), Federal University of Bahia, Salvador, Bahia, Brazil.
| | | | - Ivo Lebrun
- Laboratory of Biochemistry and Biophysics, Butantan Institute, São Paulo, Brazil
| | - Bruno Lomonte
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - Alberto Alape-Girón
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
| | - José María Gutiérrez
- Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica
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Structural and evolutionary insights into endogenous alpha-phospholipase A 2 inhibitors of Latin American pit vipers. Toxicon 2016; 112:35-44. [DOI: 10.1016/j.toxicon.2016.01.058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 01/16/2016] [Accepted: 01/20/2016] [Indexed: 11/18/2022]
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Aird SD, Aggarwal S, Villar-Briones A, Tin MMY, Terada K, Mikheyev AS. Snake venoms are integrated systems, but abundant venom proteins evolve more rapidly. BMC Genomics 2015; 16:647. [PMID: 26315097 PMCID: PMC4552096 DOI: 10.1186/s12864-015-1832-6] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 08/07/2015] [Indexed: 12/19/2022] Open
Abstract
Background While many studies have shown that extracellular proteins evolve rapidly, how selection acts on them remains poorly understood. We used snake venoms to understand the interaction between ecology, expression level, and evolutionary rate in secreted protein systems. Venomous snakes employ well-integrated systems of proteins and organic constituents to immobilize prey. Venoms are generally optimized to subdue preferred prey more effectively than non-prey, and many venom protein families manifest positive selection and rapid gene family diversification. Although previous studies have illuminated how individual venom protein families evolve, how selection acts on venoms as integrated systems, is unknown. Results Using next-generation transcriptome sequencing and mass spectrometry, we examined microevolution in two pitvipers, allopatrically separated for at least 1.6 million years, and their hybrids. Transcriptomes of parental species had generally similar compositions in regard to protein families, but for a given protein family, the homologs present and concentrations thereof sometimes differed dramatically. For instance, a phospholipase A2 transcript comprising 73.4 % of the Protobothrops elegans transcriptome, was barely present in the P. flavoviridis transcriptome (<0.05 %). Hybrids produced most proteins found in both parental venoms. Protein evolutionary rates were positively correlated with transcriptomic and proteomic abundances, and the most abundant proteins showed positive selection. This pattern holds with the addition of four other published crotaline transcriptomes, from two more genera, and also for the recently published king cobra genome, suggesting that rapid evolution of abundant proteins may be generally true for snake venoms. Looking more broadly at Protobothrops, we show that rapid evolution of the most abundant components is due to positive selection, suggesting an interplay between abundance and adaptation. Conclusions Given log-scale differences in toxin abundance, which are likely correlated with biosynthetic costs, we hypothesize that as a result of natural selection, snakes optimize return on energetic investment by producing more of venom proteins that increase their fitness. Natural selection then acts on the additive genetic variance of these components, in proportion to their contributions to overall fitness. Adaptive evolution of venoms may occur most rapidly through changes in expression levels that alter fitness contributions, and thus the strength of selection acting on specific secretome components. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1832-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Steven D Aird
- Okinawa Institute of Science and Technology Graduate University, Tancha 1919-1, Onna-son, Kunigami-gun, Okinawa-ken, 904-0412, Japan.
| | - Shikha Aggarwal
- Okinawa Institute of Science and Technology Graduate University, Tancha 1919-1, Onna-son, Kunigami-gun, Okinawa-ken, 904-0412, Japan. .,University School of Environment Management, Guru Gobind Singh Indraprastha University, Sector 16C, Dwarka, New Delhi, 110078, India.
| | - Alejandro Villar-Briones
- Okinawa Institute of Science and Technology Graduate University, Tancha 1919-1, Onna-son, Kunigami-gun, Okinawa-ken, 904-0412, Japan.
| | - Mandy Man-Ying Tin
- Okinawa Institute of Science and Technology Graduate University, Tancha 1919-1, Onna-son, Kunigami-gun, Okinawa-ken, 904-0412, Japan.
| | - Kouki Terada
- Okinawa Prefectural Institute of Health and the Environment, Biology and Ecology Group, 2003 Ozato, Ozato, Nanjo-shi, Okinawa, 901-1202, Japan.
| | - Alexander S Mikheyev
- Okinawa Institute of Science and Technology Graduate University, Tancha 1919-1, Onna-son, Kunigami-gun, Okinawa-ken, 904-0412, Japan. .,Research School of Biology, Australian National University, Canberra, ACT 0200, Australia.
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Laustsen AH, Gutiérrez JM, Lohse B, Rasmussen AR, Fernández J, Milbo C, Lomonte B. Snake venomics of monocled cobra (Naja kaouthia) and investigation of human IgG response against venom toxins. Toxicon 2015; 99:23-35. [DOI: 10.1016/j.toxicon.2015.03.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 02/28/2015] [Accepted: 03/10/2015] [Indexed: 11/27/2022]
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Calvete JJ, Sanz L, Pérez A, Borges A, Vargas AM, Lomonte B, Angulo Y, Gutiérrez JM, Chalkidis HM, Mourão RH, Furtado MFD, Moura-Da-Silva AM. Snake population venomics and antivenomics of Bothrops atrox: Paedomorphism along its transamazonian dispersal and implications of geographic venom variability on snakebite management. J Proteomics 2011; 74:510-27. [DOI: 10.1016/j.jprot.2011.01.003] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 12/28/2010] [Accepted: 01/10/2011] [Indexed: 11/25/2022]
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Doley R, Mackessy SP, Kini RM. Role of accelerated segment switch in exons to alter targeting (ASSET) in the molecular evolution of snake venom proteins. BMC Evol Biol 2009; 9:146. [PMID: 19563684 PMCID: PMC2711939 DOI: 10.1186/1471-2148-9-146] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 06/30/2009] [Indexed: 11/19/2022] Open
Abstract
Background Snake venom toxins evolve more rapidly than other proteins through accelerated changes in the protein coding regions. Previously we have shown that accelerated segment switch in exons to alter targeting (ASSET) might play an important role in its functional evolution of viperid three-finger toxins. In this phenomenon, short sequences in exons are radically changed to unrelated sequences and hence affect the folding and functional properties of the toxins. Results Here we analyzed other snake venom protein families to elucidate the role of ASSET in their functional evolution. ASSET appears to be involved in the functional evolution of three-finger toxins to a greater extent than in several other venom protein families. ASSET leads to replacement of some of the critical amino acid residues that affect the biological function in three-finger toxins as well as change the conformation of the loop that is involved in binding to specific target sites. Conclusion ASSET could lead to novel functions in snake venom proteins. Among snake venom serine proteases, ASSET contributes to changes in three surface segments. One of these segments near the substrate binding region is known to affect substrate specificity, and its exchange may have significant implications for differences in isoform catalytic activity on specific target protein substrates. ASSET therefore plays an important role in functional diversification of snake venom proteins, in addition to accelerated point mutations in the protein coding regions. Accelerated point mutations lead to fine-tuning of target specificity, whereas ASSET leads to large-scale replacement of multiple functionally important residues, resulting in change or gain of functions.
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Affiliation(s)
- Robin Doley
- Department of Biological Sciences, National University of Singapore, Singapore.
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Accelerated evolution of small serum proteins (SSPs)—The PSP94 family proteins in a Japanese viper. Gene 2008; 426:7-14. [DOI: 10.1016/j.gene.2008.08.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 08/19/2008] [Accepted: 08/26/2008] [Indexed: 11/18/2022]
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Doley R, Pahari S, Mackessy SP, Kini RM. Accelerated exchange of exon segments in Viperid three-finger toxin genes (Sistrurus catenatus edwardsii; Desert Massasauga). BMC Evol Biol 2008; 8:196. [PMID: 18606022 PMCID: PMC2474615 DOI: 10.1186/1471-2148-8-196] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Accepted: 07/08/2008] [Indexed: 11/10/2022] Open
Abstract
Background Snake venoms consist primarily of proteins and peptides showing a myriad of potent biological activities which have been shaped by both adaptive and neutral selective forces. Venom proteins are encoded by multigene families that have evolved through a process of gene duplication followed by accelerated evolution in the protein coding region. Results Here we report five gene structures of three-finger toxins from a viperid snake, Sistrurus catenatus edwardsii. These toxin genes are structured similarly to elapid and hydrophiid three-finger toxin genes, with two introns and three exons. Both introns and exons show distinct patterns of segmentation, and the insertion/deletion of segments may define their evolutionary history. The segments in introns, when present, are highly similar to their corresponding segments in other members of the gene family. In contrast, some segments in the exons show high similarity, while others are often distinctly different among corresponding regions of the isoforms. Conclusion Ordered, conserved exon structure strongly suggests that segments in corresponding regions in exons have been exchanged with distinctly different ones during the evolution of these genes. Such a "switching" of segments in exons may result in drastically altering the molecular surface topology and charge, and hence the molecular targets of these three-finger toxins. Thus the phenomenon of accelerated segment switch in exons to alter targeting (ASSET) may play an important role in the evolution of three-finger toxins, resulting in a family of toxins with a highly conserved structural fold but widely varying biological activities.
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Affiliation(s)
- Robin Doley
- Protein Science Laboratory, Department of Biological Sciences, National University of Singapore, 117543, Singapore.
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Snake venomics of the South and Central American Bushmasters. Comparison of the toxin composition of Lachesis muta gathered from proteomic versus transcriptomic analysis. J Proteomics 2008; 71:46-60. [DOI: 10.1016/j.jprot.2007.10.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2007] [Revised: 10/17/2007] [Accepted: 10/19/2007] [Indexed: 11/19/2022]
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Lynch VJ. Inventing an arsenal: adaptive evolution and neofunctionalization of snake venom phospholipase A2 genes. BMC Evol Biol 2007; 7:2. [PMID: 17233905 PMCID: PMC1783844 DOI: 10.1186/1471-2148-7-2] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 01/18/2007] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Gene duplication followed by functional divergence has long been hypothesized to be the main source of molecular novelty. Convincing examples of neofunctionalization, however, remain rare. Snake venom phospholipase A2 genes are members of large multigene families with many diverse functions, thus they are excellent models to study the emergence of novel functions after gene duplications. RESULTS Here, I show that positive Darwinian selection and neofunctionalization is common in snake venom phospholipase A2 genes. The pattern of gene duplication and positive selection indicates that adaptive molecular evolution occurs immediately after duplication events as novel functions emerge and continues as gene families diversify and are refined. Surprisingly, adaptive evolution of group-I phospholipases in elapids is also associated with speciation events, suggesting adaptation of the phospholipase arsenal to novel prey species after niche shifts. Mapping the location of sites under positive selection onto the crystal structure of phospholipase A2 identified regions evolving under diversifying selection are located on the molecular surface and are likely protein-protein interactions sites essential for toxin functions. CONCLUSION These data show that increases in genomic complexity (through gene duplications) can lead to phenotypic complexity (venom composition) and that positive Darwinian selection is a common evolutionary force in snake venoms. Finally, regions identified under selection on the surface of phospholipase A2 enzymes are potential candidate sites for structure based antivenin design.
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Affiliation(s)
- Vincent J Lynch
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA.
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Soto JG, Powell RL, Reyes SR, Wolana L, Swanson LJ, Sanchez EE, Perez JC. Genetic variation of a disintegrin gene found in the American copperhead snake (Agkistrodon contortrix). Gene 2006; 373:1-7. [PMID: 16546330 DOI: 10.1016/j.gene.2005.11.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2005] [Accepted: 11/09/2005] [Indexed: 10/24/2022]
Abstract
Disintegrins are small, non-enzymatic proteins produced in snake venom. PCR and DNA sequencing analysis of genomic DNA for all subspecies of the copperhead snake (Agkistrodon contortrix) were analyzed for the presence of a disintegrin gene. Four samples each of the subspecies: A. c. contortrix, A. c. laticinctus, A. c. mokasen, A. c. phaeogaster, and A. c. pictigaster were collected from different locations across their geographic range and analyzed. A single PCR fragment from each sample was obtained, containing exon and intron sequences. The disintegrins identified in this study shared the highest amino acid identity to contortrostatin and acostatin b chain. Neighbor joining analysis of the disintegrin haplotypes and bootstrap tests of significance grouped the A. contortrix subspecies into two clades. The A. c. mokasen samples collected in Kentucky were grouped in one clade, while the A. c. contortrix, A. c. laticinctus, A. c. phaeogaster, and A. c. pictigaster samples collected in Texas, Louisiana, and Missouri were grouped in a different clade. Analysis of molecular variance (AMOVA) and PhiST pairwise comparisons showed significant genetic variation between subspecies. Nucleotide substitution analysis suggests the rapid evolution of disintegrin genes in A. contortrix subspecies.
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Affiliation(s)
- Julio G Soto
- Biological Sciences Department, San Jose State University, One Washington Square, Duncan Hall 254, San Jose, CA 95192-0100, United States.
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Furtado MFD. Biological and immunological properties of the venom of Bothrops alcatraz, an endemic species of pitviper from Brazil. Comp Biochem Physiol C Toxicol Pharmacol 2005; 141:117-23. [PMID: 16002343 DOI: 10.1016/j.cca.2004.09.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Revised: 09/19/2004] [Accepted: 09/20/2004] [Indexed: 11/19/2022]
Abstract
Bothrops alcatraz is a new pitviper species derived from the Bothrops jararaca group, whose natural habitat is situated in Alcatrazes Archipelago, a group of marine islands near São Paulo State coast in Brazil. Herein, the biological and biochemical properties of venoms of four adult specimens of B. alcatraz were examined comparatively to a reference pool of Bothrops jararaca venom. Both venoms showed similar activities and electrophoretic patterns, but B. alcatraz venom showed three protein bands of molecular masses of 97, 80 and 38 kDa that were not present in B. jararaca reference venom. The i.p. median lethal dose of B. alcatraz venom ranged from 5.1 to 6.6 mg/kg, while it was 1.5 mg/kg for B. jararaca venom. The minimum hemorrhagic dose of B. jararaca venom was 0.63, whereas 2.28 mug/mouse for B. alcatraz venom. In contrast, B. alcatraz venom was more potent in regard to procoagulant and proteolytic activities. These differences were supported by western blotting and neutralization tests, employing commercial bothropic antivenom, which showed that hemorrhagic and lethal activities of B. alcatraz venom were less effectively inhibited than B. jararaca venom. Such results evidence that B. alcatraz shows quantitative and qualitative differences in venom composition in comparison with its B. jararaca relatives, which might represent an optimization of venom towards a specialized diet.
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Affiliation(s)
- M F D Furtado
- Laboratório de Herpetologia, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900, São Paulo, SP, Brazil.
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Li M, Fry BG, Kini RM. Putting the brakes on snake venom evolution: the unique molecular evolutionary patterns of Aipysurus eydouxii (Marbled sea snake) phospholipase A2 toxins. Mol Biol Evol 2005; 22:934-41. [PMID: 15635056 DOI: 10.1093/molbev/msi077] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Accelerated evolution of toxins is a unique feature of venoms, with the toxins evolving via the birth-and-death mode of molecular evolution. The venoms of sea snakes, however, are remarkably simple in comparison to those of land snakes, which contain highly complex venoms. Aipysurus eydouxii (Marbled sea snake) is a particularly unique sea snake, feeding exclusively upon fish eggs. Secondary to this ecological change, the fangs have been lost and the venom glands greatly atrophied. We recently showed that the only neurotoxin (a three-finger toxin) gene found in the sea snake A. eydouxii has a dinucleotide deletion, resulting in the loss of neurotoxic activity. During these studies, we isolated and identified a number of cDNA clones encoding isozymes of phospholipase A(2) (PLA(2)) toxins from its venom gland. Sixteen unique PLA(2) clones were sequenced from the cDNA library and TA cloning of reverse transcription-polymerase chain reaction products. Phylogenetic analysis of these clones revealed that less diversification of the PLA(2) toxins has occurred in the A. eydouxii venom gland in comparison to equivalent terrestrial and other marine snakes. As there is no longer a positive selection pressure acting upon the venom, mutations have accumulated in the toxin-coding regions that would have otherwise had a deleterious effect upon the ability to use the venom for prey capture. Such mutations include substitutions of highly conserved residues; in one clone, the active site His(48) is replaced by Arg, and in two other clones, highly conserved cysteine residues are replaced. These mutations significantly affect the functional and structural properties of these PLA(2) enzymes, respectively. Thus, in A. eydouxii, the loss of the main neurotoxin is accompanied by a much slower rate of molecular evolution of the PLA(2) toxins as a consequence of the snake's shift in ecological niche. This is the first case of decelerated evolution of toxins in snake venom.
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Affiliation(s)
- Min Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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Abstract
Venom phospholipase A2 (PLA2) enzymes share similarity in structure and catalytic function with mammalian enzymes. However, in contrast to mammalian enzymes, many are toxic and induce a wide spectrum of pharmacological effects. Thus structure-function relationship of this group of small proteins is subtle, but complex puzzle to protein biochemists, molecular biologists, toxinologists, pharmacologists and physiologists. This review describes the present status of our understanding of their structure, function and mechanism. It was proposed that their unique ability to 'target' themselves to a specific organ or tissue is due to their high affinity binding to specific proteins which act as receptors (more precisely, acceptors). This specific binding of PLA2 is conferred by the presence of a 'pharmacological site' on its surface which is independent of the catalytic site. The high affinity interaction of PLA2 with its acceptor (or target protein) is probably due to the complementarity, in terms of charges, hydrophobicity and van der Waal's contact surfaces, between the pharmacological site and the binding site on the surface of the acceptor protein. Upon binding to the target, the PLA2 can induce its pharmacological effects by mechanisms either dependent on or independent of its catalytic activity. Because of the unprecedented wide spectrum of specific targeting to various tissues and organs, identification of the pharmacological sites has potential for exploitation in development of novel systems useful for 'delivering' specific proteins to a particular target tissue or organ. Thus research in this field will provide a lot of exciting opportunities.
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Affiliation(s)
- R Manjunatha Kini
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543.
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Ohno M, Chijiwa T, Oda-Ueda N, Ogawa T, Hattori S. Molecular evolution of myotoxic phospholipases A2 from snake venom. Toxicon 2004; 42:841-54. [PMID: 15019486 DOI: 10.1016/j.toxicon.2003.11.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
After two decades of study, we draw the conclusion that venom-gland phospholipase A2 (PLA2) isozymes, including PLA2 myotoxins of Crotalinae snakes, have evolved in an accelerated manner to acquire their diverse physiological activities. In this review, we describe how accelerated evolution of venom PLA2 isozymes was discovered. This type of evolution is fundamental for other venom isozyme systems. Accelerated evolution of venom PLA2 isozyme genes is due to rapid change in exons, but not in introns and the flanking regions, being completely opposite to the case of the ordinary isozyme genes. The molecular mechanism by which proper base substitutions had occurred in the particular sites of venom isozyme genes is a puzzle to be solved in future studies. It should be noted that accelerated evolution occurred until the isozymes had acquired their particular function and, since then, they have evolved with less frequent mutation, possibly for functional conservation. We also found that interisland mutations occurred in venom PLA2 isozymes. The relationships between mutation and its driving force are speculative and the real mechanism remains a mystery.
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Affiliation(s)
- Motonori Ohno
- Department of Applied Life Science, Faculty of Engineering, Sojo University, Kumamoto 860-0082, Japan.
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Kuch U, Molles BE, Omori-Satoh T, Chanhome L, Samejima Y, Mebs D. Identification of alpha-bungarotoxin (A31) as the major postsynaptic neurotoxin, and complete nucleotide identity of a genomic DNA of Bungarus candidus from Java with exons of the Bungarus multicinctus alpha-bungarotoxin (A31) gene. Toxicon 2003; 42:381-90. [PMID: 14505938 DOI: 10.1016/s0041-0101(03)00168-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The Malayan krait (Bungarus candidus) is one of the most medically significant snake species in Southeast Asia. No specific antivenom exists to treat envenoming by this species. Death within 30 min after its bite has been reported from Java, suggesting the presence of highly lethal postsynaptic neurotoxins in the venom of these snakes. We purified and identified the major postsynaptic toxin in the venom of B. candidus from Java. The toxin was indistinguishable from alpha-bungarotoxin (A31), a toxin originally isolated from Bungarus multicinctus, in its mass (7983.75 Da), LD50 (0.23 microg/g in mice i.p.), affinity to nicotinic acetylcholine receptors, and by its 40 N-terminal amino acid residues as determined by Edman degradation. Identity with alpha-bungarotoxin was confirmed by cloning and sequencing a genomic DNA from B. candidus which encodes the 74 amino acid sequence of alpha-bungarotoxin (A31) and part of its signal peptide, revealing complete identity to the alpha-bungarotoxin (A31) gene in exon and 98.9% identity in intron sequences. The entire mitochondrial cytochrome b gene of the krait species B. candidus from Java and B. multicinctus from Taiwan was sequenced for comparison, suggesting that these snakes are phylogenetically closely related. alpha-Bungarotoxin appears to be widely present and conserved in Southeast and East Asian black-and-white kraits across populations and taxa.
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Affiliation(s)
- Ulrich Kuch
- Zentrum der Rechtsmedizan, Klinikum der Johann Wolfgang Goethe-Universität, Kennedyallee 104, 60596 Frankfurt am Main, Germany.
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Tsai IH, Hsu HY, Wang YM. A novel phospholipase A(2) from the venom glands of Bungarus candidus: cloning and sequence-comparison. Toxicon 2002; 40:1363-7. [PMID: 12220723 DOI: 10.1016/s0041-0101(02)00150-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The presence of phospholipase A(2) (PLA(2)) in the venom of Malayan krait (Bungarus candidus) and its structure were studied. The PLA(2) cDNAs from the venom gland of B. candidus (Indonesia origin) were amplified by the polymerase chain reactions (PCR) and cloned. The primers used were based on the cDNA sequences of several homologous B. multicinctus venom PLA(2)s. In addition to the A-chains of beta-bungarotoxins, a novel B. candidus PLA(2) was cloned and its full amino acid sequence deduced. Having totally 125 amino acid residues, the PLA(2) contains a pancreatic loop and is 61% identical to the acidic PLA(2) of king cobra venom. However, the enzyme was not detected from the venom sample. Its structural relationships to other elapid venom PLA(2)s were analyzed with a phylogenetic tree and discussed.
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Affiliation(s)
- Inn-Ho Tsai
- Institute of Biological Chemistry, Academia Sinica, and College of Sciences, National Taiwan University, PO Box 23-106, 106, Taipei, Taiwan, ROC.
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Tsai IH, Chen YH, Wang YM, Liau MY, Lu PJ. Differential Expression and Geographic Variation of the Venom Phospholipases A2 of Calloselasma rhodostoma and Trimeresurus mucrosquamatus. Arch Biochem Biophys 2001; 387:257-64. [PMID: 11370849 DOI: 10.1006/abbi.2000.2229] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the geographic variations in venoms of two medically important pitvipers, we have purified and characterized the phospholipases A2 (PLA2s) from the pooled venoms of Calloselasma rhodostoma from Malaysia, Thailand, Indonesia, and Vietnam, as well as the individual venom of Trimeresurus mucrosquamatus collected from both North and South Taiwan. Enzymatic and pharmacological activities of the purified PLA2s were also investigated. The complete amino acid sequences of the purified PLA2s were determined by sequencing the corresponding cDNAs from the venom gland and shown to be consistent with their molecular weight data and the N-terminal sequences. All the geographic venom samples of C. rhodostoma contain a major noncatalytic basic PLA2-homolog and two or three acidic PLA2s in different proportions. These acidic PLA2s contain Glu6-substitutions and show distinct inhibiting specificities toward the platelets from human and rabbit. We also found that the T. mucrosquamatus venoms from North Taiwan but not those from South Taiwan contain an Arg6-PLA2 designated as TmPL-III. Its amino acid sequence is reported for the first time. This enzyme is structurally almost identical to the low- or nonexpressed Arg6-PLA2 from C. rhodostoma venom gland, and thus appears to be a regressing venom component in both of the Asian pitvipers.
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Affiliation(s)
- I H Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan, Republic of China.
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Wu PF, Chang LS. Genetic organization of A chain and B chain of beta-bungarotoxin from Taiwan banded krait (Bungarus multicinctus). A chain genes and B chain genes do not share a common origin. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:4668-75. [PMID: 10903499 DOI: 10.1046/j.1432-1327.2000.01518.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
beta-Bungarotoxin, the main presynaptic neurotoxin purified from the venom of Bungarus multicinctus, consists of two dissimilar polypeptide chains, the A chain and the B chain, cross-linked by an interchain disulfide bond. In this study, A and B chain genes isolated from the liver of B. multicinctus encoded the A and B chain precursors, respectively. Analyses of the coding regions of the A and B chain genes revealed that both consist of three exons and two introns. The sequences of all exon/intron junctions agree with the GT/AG rule. However, sequence alignment and phylogenetic analysis did not support that the evolution of A and B chain genes are closely related. Comparative analysis of A chain genes with Viperinae and Crotalinae phospholipase A2 genes indicated that genetic divergence of the A chain and phospholipase A2s was in accordance with their family. Moreover, evolutionary divergence of the intron and exon regions of the A chain, as observed for phospholipase A2 genes, was not consistent. Noticeably, the transcription of A and B chain genes may be regulated under different transcription factors as revealed by analyses of their promoter sequences. In terms of the finding that A and B chains are encoded separately by different genes, this strongly supports the view that the intact beta-bungarotoxin molecules should be derived from the pairing of A and B chains after their mRNAs are translated.
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Affiliation(s)
- P F Wu
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Taiwan
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