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Hiremath K, Dodakallanavar J, Sampat GH, Patil VS, Harish DR, Chavan R, Hegde HV, Roy S. Three finger toxins of elapids: structure, function, clinical applications and its inhibitors. Mol Divers 2023:10.1007/s11030-023-10734-3. [PMID: 37749455 DOI: 10.1007/s11030-023-10734-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 09/18/2023] [Indexed: 09/27/2023]
Abstract
The WHO lists snakebite as a "neglected tropical disease". In tropical and subtropical areas, envenoming is an important public health issue. This review article describes the structure, function, chemical composition, natural inhibitors, and clinical applications of Elapids' Three Finger Toxins (3FTX) using scientific research data. The primary venomous substance belonging to Elapidae is 3FTX, that targets nAChR. Three parallel β-sheets combine to create 3FTX, which has four or five disulfide bonds. The three primary types of 3FTX are short-chain, long-chain, and nonconventional 3FTX. The functions of 3FTX depend on the specific toxin subtype and the target receptor or ion channel. The well-known effect of 3FTX is probably neurotoxicity because of the severe consequences of muscular paralysis and respiratory failure in snakebite victims. 3FTX have also been studied for their potential clinical applications. α-bungarotoxin has been used as a molecular probe to study the structure and function of nAChRs (Nicotinic Acetylcholine Receptors). Acid-sensing ion channel (ASIC) isoforms 1a and 1b are inhibited by Mambalgins, derived from Black mamba venom, which hinders their function and provide an analgesic effect. α- Cobra toxin is a neurotoxin purified from Chinese cobra (Naja atra) binds to nAChR at the neuronal junction and causes an analgesic effect for moderate to severe pain. Some of the plants and their compounds have been shown to inhibit the activity of 3FTX, and their mechanisms of action are discussed.
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Affiliation(s)
- Kashinath Hiremath
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
- KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590010, India
| | - Jagadeesh Dodakallanavar
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
- KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590010, India
| | - Ganesh H Sampat
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
- KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590010, India
| | - Vishal S Patil
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
- KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590010, India
| | - Darasaguppe R Harish
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India.
| | - Rajashekar Chavan
- KLE College of Pharmacy, Belagavi, KLE Academy of Higher Education and Research, Belagavi, Karnataka, 590010, India.
| | - Harsha V Hegde
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
| | - Subarna Roy
- ICMR-National Institute of Traditional Medicine, Belagavi, Karnataka, 590010, India
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Tasoulis T, Isbister GK. A current perspective on snake venom composition and constituent protein families. Arch Toxicol 2023; 97:133-53. [PMID: 36437303 DOI: 10.1007/s00204-022-03420-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 11/09/2022] [Indexed: 11/28/2022]
Abstract
Snake venoms are heterogeneous mixtures of proteins and peptides used for prey subjugation. With modern proteomics there has been a rapid expansion in our knowledge of snake venom composition, resulting in the venom proteomes of 30% of vipers and 17% of elapids being characterised. From the reasonably complete proteomic coverage of front-fanged snake venom composition (179 species-68 species of elapids and 111 species of vipers), the venoms of vipers and elapids contained 42 different protein families, although 18 were only reported in < 5% of snake species. Based on the mean abundance and occurrence of the 42 protein families, they can be classified into 4 dominant, 6 secondary, 14 minor, and 18 rare protein families. The dominant, secondary and minor categories account for 96% on average of a snake's venom composition. The four dominant protein families are: phospholipase A2 (PLA2), snake venom metalloprotease (SVMP), three-finger toxins (3FTx), and snake venom serine protease (SVSP). The six secondary protein families are: L-amino acid oxidase (LAAO), cysteine-rich secretory protein (CRiSP), C-type lectins (CTL), disintegrins (DIS), kunitz peptides (KUN), and natriuretic peptides (NP). Venom variation occurs at all taxonomic levels, including within populations. The reasons for venom variation are complex, as variation is not always associated with geographical variation in diet. The four dominant protein families appear to be the most important toxin families in human envenomation, being responsible for coagulopathy, neurotoxicity, myotoxicity and cytotoxicity. Proteomic techniques can be used to investigate the toxicological profile of a snake venom and hence identify key protein families for antivenom immunorecognition.
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Palasuberniam P, Tan KY, Tan CH. De novo venom gland transcriptomics of Calliophis bivirgata flaviceps: uncovering the complexity of toxins from the Malayan blue coral snake. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20210024. [PMID: 34616441 PMCID: PMC8476087 DOI: 10.1590/1678-9199-jvatitd-2021-0024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/12/2021] [Indexed: 03/03/2023] Open
Abstract
Background: The Malayan blue coral snake, Calliophis bivirgata
flaviceps, is a medically important venomous snake in Southeast
Asia. However, the complexity and diversity of its venom genes remain little
explored. Methods: To address this, we applied high-throughput next-generation sequencing to
profile the venom gland cDNA libraries of C. bivirgata
flaviceps. The transcriptome was de novo
assembled, followed by gene annotation, multiple sequence alignment and
analyses of the transcripts. Results: A total of 74 non-redundant toxin-encoding genes from 16 protein families
were identified, with 31 full-length toxin transcripts. Three-finger toxins
(3FTx), primarily delta-neurotoxins and cardiotoxin-like/cytotoxin-like
proteins, were the most diverse and abundantly expressed. The major 3FTx
(Cb_FTX01 and Cb_FTX02) are highly similar to calliotoxin, a
delta-neurotoxin previously reported in the venom of C.
bivirgata. This study also revealed a conserved tyrosine
residue at position 4 of the cardiotoxin-like/cytotoxin-like protein genes
in the species. These variants, proposed as Y-type CTX-like proteins, are
similar to the H-type CTX from cobras. The substitution is conservative
though, preserving a less toxic form of elapid CTX-like protein, as
indicated by the lack of venom cytotoxicity in previous laboratory and
clinical findings. The ecological role of these toxins, however, remains
unclear. The study also uncovered unique transcripts that belong to
phospholipase A2 of Groups IA and IB, and snake venom
metalloproteinases of PIII subclass, which show sequence variations from
those of Asiatic elapids. Conclusion: The venom gland transcriptome of C. bivirgata flaviceps from
Malaysia was de novo assembled and annotated. The diversity
and expression profile of toxin genes provide insights into the biological
and medical importance of the species.
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Affiliation(s)
- Praneetha Palasuberniam
- Venom Research and Toxicology Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya. Kuala Lumpur, Malaysia.,Department of Biomedical Sciences, University Malaysia Sabah, Faculty of Medicine and Health Sciences, Kota Kinabalu, Sabah, Malaysia
| | - Kae Yi Tan
- Protein and Interactomics Laboratory, Department of Molecular Medicine, Faculty of Medicine, University of Malaya. Kuala Lumpur, Malaysia
| | - Choo Hock Tan
- Venom Research and Toxicology Laboratory, Department of Pharmacology, Faculty of Medicine, University of Malaya. Kuala Lumpur, Malaysia
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Beraldo E, Coelho GR, Sciani JM, Pimenta DC. Proteomic characterization of Naja mandalayensis venom. J Venom Anim Toxins Incl Trop Dis 2021; 27:e20200125. [PMID: 34394208 PMCID: PMC8331017 DOI: 10.1590/1678-9199-jvatitd-2020-0125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 03/31/2021] [Indexed: 12/24/2022] Open
Abstract
Background Naja mandalayensis is a spitting cobra from Myanmar. To the
best of our knowledge, no studies on this venom composition have been
conducted so far. On the other hand, few envenomation descriptions state
that it elicits mainly local inflammation in the victims’ eyes, the
preferred target of this spiting cobra. Symptoms would typically include
burning and painful sensation, conjunctivitis, edema and temporary loss of
vision. Methods We have performed a liquid-chromatography (C18-RP-HPLC) mass spectrometry
(ESI-IT-TOF/MS) based approach in order to biochemically characterize
N. mandalayensis venom. Results A wide variety of three-finger toxins (cardiotoxins) and metallopeptidases
were detected. Less abundant, but still representative, were cysteine-rich
secretory proteins, L-amino-acid oxidases, phospholipases A2,
venom 5'-nucleotidase and a serine peptidase inhibitor. Other proteins were
present, but were detected in a relatively small concentration. Conclusion The present study set the basis for a better comprehension of the
envenomation from a molecular perspective and, by increasing the interest
and information available for this species, allows future venom comparisons
among cobras and their diverse venom proteins.
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Affiliation(s)
- Emídio Beraldo
- Laboratory of Biochemistry and Biophysics, Butantan Institute, São Paulo, SP, Brazil.,Graduation Program in Science - Toxinology, Butantan Institute, São Paulo, SP, Brazil
| | | | - Juliana Mozer Sciani
- Multidisciplinary Research Laboratory, São Francisco University, Bragança Paulista, SP, Brazil
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Bénard-Valle M, Neri-Castro E, Elizalde-Morales N, Olvera-Rodríguez A, Strickland J, Acosta G, Alagón A. Protein composition and biochemical characterization of venom from Sonoran Coral Snakes (Micruroides euryxanthus). Biochimie 2021; 182:206-216. [PMID: 33485932 DOI: 10.1016/j.biochi.2021.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 11/16/2022]
Abstract
The elapid genus, Micruroides, is considered the sister clade of all New World coral snakes (Genus Micrurus), is monotypic, and is represented by Sonoran Coral Snakes, Micruroides euryxanthus. Coral snakes of the genus Micrurus have been reported to have venoms that are predominantly composed of phospholipases A2 (PLA2) or three finger toxins (3FTx), but the venoms of the genus Micruroides are almost completely unstudied. Here, we present the first description of the venom of M. euryxanthus including identification of some proteins as well as transcriptomic, and biological activity assays. The most abundant components within M. euryxanthus venom are 3FTxs (62.3%) and there was relatively low proportion of PLA2s (14.2%). The venom phenotype supports the hypothesis that the common ancestor of Micrurus and Micruroides had a 3FTx-dominated venom. Within the venom, there were two nearly identical α-neurotoxins (α-Ntx), one of which was designated Eurytoxin, that account for approximately 60% of the venom's lethality to mice. Eurytoxin was cloned, expressed in a soluble and active form, and used to produce rabbit hyperimmune serum. This allowed the analysis of its immunochemical properties, showing them to be different from the recombinant αNTx D.H., present in the venoms of some species of Micrurus. Finally, we observed that the commercial antivenom produced in Mexico for coral snake envenomation is unable to neutralize the lethality from M. euryxanthus venom. This work allowed the classification of Micruroides venom into the 3FTx-predominant group and identified the main components responsible for toxicity to mice.
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Affiliation(s)
- Melisa Bénard-Valle
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Edgar Neri-Castro
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Nicolás Elizalde-Morales
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Alejandro Olvera-Rodríguez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico
| | - Jason Strickland
- Department of Biological Sciences, Clemson University, Clemson, SC, 29632, USA; Department of Biology, University of South Alabama, Mobile, AL, 36688, USA
| | - Gerardo Acosta
- MIVIA. Museo Itinerante de Vida Animal, Hermosillo, Sonora, Mexico
| | - Alejandro Alagón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad # 2001, Colonia Chamilpa, CP: 62210, Cuernavaca, Morelos, Mexico.
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Kini RM, Koh CY. Snake venom three-finger toxins and their potential in drug development targeting cardiovascular diseases. Biochem Pharmacol 2020; 181:114105. [PMID: 32579959 DOI: 10.1016/j.bcp.2020.114105] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/13/2020] [Accepted: 06/17/2020] [Indexed: 12/15/2022]
Abstract
Cardiovascular diseases such as coronary and peripheral artery diseases, venous thrombosis, stroke, hypertension, and heart failure are enormous burden to health and economy globally. Snake venoms have been the sources of discovery of successful therapeutics targeting cardiovascular diseases. For example, the first-in-class angiotensin-converting enzyme inhibitor captopril was designed largely based on bradykinin-potentiating peptides from Bothrops jararaca venom. In the recent years, sensitive and high throughput approaches drive discovery and cataloging of new snake venom toxins. As one of the largest class of snake venom toxin, there are now>700 sequences of three-finger toxins (3FTxs) available, many of which are yet to be studied. While the function of 3FTxs are normally associated with neurotoxicity, increasingly more 3FTxs have been characterized to have pharmacological effects on cardiovascular systems. Here we focus on this family of snake venom toxins and their potential in developing therapeutics against cardiovascular diseases.
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Affiliation(s)
- R Manjunatha Kini
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 117558, Singapore; Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 117600, Singapore
| | - Cho Yeow Koh
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 119228, Singapore.
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Conlon JM, Attoub S, Musale V, Leprince J, Casewell NR, Sanz L, Calvete JJ. Isolation and characterization of cytotoxic and insulin-releasing components from the venom of the black-necked spitting cobra Naja nigricollis (Elapidae). Toxicon X 2020; 6:100030. [PMID: 32550585 PMCID: PMC7285909 DOI: 10.1016/j.toxcx.2020.100030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/18/2020] [Accepted: 03/09/2020] [Indexed: 01/09/2023] Open
Abstract
Four peptides with cytotoxic activity against BRIN-BD11 rat clonal β-cells were purified from the venom of the black-necked spitting cobra Naja nigricollis using reversed-phase HPLC. The peptides were identified as members of the three-finger superfamily of snake toxins by ESI-MS/MS sequencing of tryptic peptides. The most potent peptide (cytotoxin-1N) showed strong cytotoxic activity against three human tumor-derived cell lines (LC50 = 0.8 ± 0.2 μM for A549 non-small cell lung adenocarcinoma cells; LC50 = 7 ± 1 μM for MDA-MB-231 breast adenocarcinoma cells; and LC50 = 9 ± 1 μM for HT-29 colorectal adenocarcinoma cells). However, all the peptides were to varying degrees cytotoxic against HUVEC human umbilical vein endothelial cells (LC50 in the range 2–22 μM) and cytotoxin-2N was moderately hemolytic (LC50 = 45 ± 3 μM against mouse erythrocytes). The lack of differential activity against cells derived from non-neoplastic tissue limits their potential for development into anti-cancer agents. In addition, two proteins in the venom, identified as isoforms of phospholipase A2, effectively stimulated insulin release from BRIN-BD11 cells (an approximately 6-fold increase in rate compared with 5.6 mM glucose alone) at a concentration (1 μM) that was not cytotoxic to the cells suggesting possible application in therapy for Type 2 diabetes. Four members of the three-finger superfamily of toxins were isolated from N. nigricollis venom. All peptides were cytotoxic to human tumor-derived cells. The peptides were also cytotoxic to non-neoplastic HUVEC cells. Two isoforms of phospholipase A2 effectively stimulated insulin release from rat clonal β-cells.
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Affiliation(s)
- J M Conlon
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Coleraine, Ireland
| | - Samir Attoub
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Vishal Musale
- Diabetes Research Group, School of Biomedical Sciences, Ulster University, Coleraine, Ireland
| | - Jérôme Leprince
- Inserm U1239, PRIMACEN, Institute for Research and Innovation in Biomedicine (IRIB), Normandy University, 76000, Rouen, France
| | - Nicholas R Casewell
- Centre for Snakebite Research & Interventions, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, Merseyside, UK
| | - Libia Sanz
- Laboratorio de Venómica Evolutiva y Traslacional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Juan J Calvete
- Laboratorio de Venómica Evolutiva y Traslacional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
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Utkin YN. Last decade update for three-finger toxins: Newly emerging structures and biological activities. World J Biol Chem 2019; 10:17-27. [PMID: 30622682 PMCID: PMC6314878 DOI: 10.4331/wjbc.v10.i1.17] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/20/2018] [Accepted: 12/05/2018] [Indexed: 02/05/2023] Open
Abstract
Three-finger toxins (TFTs) comprise one of largest families of snake venom toxins. While they are principal to and the most toxic components of the venoms of the Elapidae snake family, their presence has also been detected in the venoms of snakes from other families. The first TFT, α-bungarotoxin, was discovered almost 50 years ago and has since been used widely as a specific marker of the α7 and muscle-type nicotinic acetylcholine receptors. To date, the number of TFT amino acid sequences deposited in the UniProt Knowledgebase free-access database is more than 700, and new members are being added constantly. Although structural variations among the TFTs are not numerous, several new structures have been discovered recently; these include the disulfide-bound dimers of TFTs and toxins with nonstandard pairing of disulfide bonds. New types of biological activities have also been demonstrated for the well-known TFTs, and research on this topic has become a hot topic of TFT studies. The classic TFTs α-bungarotoxin and α-cobratoxin, for example, have now been shown to inhibit ionotropic receptors of γ-aminobutyric acid, and some muscarinic toxins have been shown to interact with adrenoceptors. New, unexpected activities have been demonstrated for some TFTs as well, such as toxin interaction with interleukin or insulin receptors and even TFT-activated motility of sperm. This minireview provides a summarization of the data that has emerged in the last decade on the TFTs and their activities.
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Affiliation(s)
- Yuri N Utkin
- Laboratory of Molecular Toxinology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
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Abstract
Three-finger toxins (TFTs) are well-recognized non-enzymatic venom proteins found in snakes. However, although TFTs exhibit accelerated evolution, the drivers of this evolution remain poorly understood. The structural complexes between long-chain α-neurotoxins, a subfamily of TFTs, and their nicotinic acetylcholine receptor targets have been determined in previous research, providing an opportunity to address such questions. In the current study, we observed several previously identified positively selected sites (PSSs) and the highly variable C-terminal loop of these toxins at the toxin/receptor interface. Of interest, analysis of the molecular adaptation of the toxin-recognition regions in the corresponding receptors provided no statistical evidence for positive selection. However, these regions accumulated abundant amino acid variations in the receptors from the prey of snakes, suggesting that accelerated substitution of TFTs could be a consequence of adaptation to these variations. To the best of our knowledge, this atypical evolution, initially discovered in scorpions, is reported in snake toxins for the first time and may be applicable for the evolution of toxins from other venomous animals.
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Affiliation(s)
- Xian-Hong Ji
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; E-mail:.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shang-Fei Zhang
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; E-mail:.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin Gao
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; E-mail:
| | - Shun-Yi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China; E-mail:
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Pla D, Petras D, Saviola AJ, Modahl CM, Sanz L, Pérez A, Juárez E, Frietze S, Dorrestein PC, Mackessy SP, Calvete JJ. Transcriptomics-guided bottom-up and top-down venomics of neonate and adult specimens of the arboreal rear-fanged Brown Treesnake, Boiga irregularis, from Guam. J Proteomics 2017; 174:71-84. [PMID: 29292096 DOI: 10.1016/j.jprot.2017.12.020] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/18/2017] [Accepted: 12/26/2017] [Indexed: 12/11/2022]
Abstract
The Brown Treesnake (Boiga irregularis) is an arboreal, nocturnal, rear-fanged venomous snake native to northern and eastern regions of Australia, Papua New Guinea and the Solomon Islands. It was inadvertently introduced onto the island of Guam during the late 1940's to early 1950's, and it has caused massive declines and extirpations of the native bird, lizard, and mammal populations. In the current study, we report the characterization of the venom proteome of an adult and a neonate B. irregularis specimens from Guam by a combination of venom gland transcriptomic and venomic analyses. Venom gland transcriptomic analysis of an adult individual identified toxins belonging to 18 protein families, with three-finger toxin isoforms being the most abundantly expressed transcripts, comprising 94% of all venom protein transcript reads. Transcripts for PIII-metalloproteinases, C-type lectins, cysteine-rich secretory proteins, acetylcholinesterases, natriuretic peptides, ficolins, phospholipase A2 (PLA2) inhibitors, PLA2s, vascular endothelial growth factors, Kunitz-type protease inhibitors, cystatins, phospholipase Bs, cobra venom factors, waprins, SVMP inhibitors, matrix metalloproteinases, and hyaluronidases were also identified, albeit, at very low abundances ranging from 0.05% to 1.7% of the transcriptome. The venom proteomes of neonate and adult B. irregularis were also both overwhelmingly (78 and 84%, respectively) dominated by monomeric and dimeric 3FTxs, followed by moderately abundant (21% (N) and 13% (A)) CRISPs, low abundance (1% (N), 3% (A)) PIII-SVMPs, and very low abundance (<0.01%) PLA2 and SVMP inhibitors. The differences in relative toxin abundances identified between neonate and adult snakes likely correlates to shifts in prey preference between the two age classes, from nearly-exclusively lizards to lizards, birds and small mammals. Immunoaffinity antivenomics with experimentally designed rabbit anti-Brown Treesnake (anti-BTS) venom IgGs against homologous venom from adult snakes demonstrated that CRISPs, PIII-SVMPs, and 60-70% of 3FTxs were effectively immunocaptured. Western blot analysis showed that all venom proteins were recognized by anti-BTS IgGs, and cross-reactivity with other rear-fanged snake venoms was also observed. Incubation of anti-BTS venom IgGs with crude B. irregularis venom resulted in a significant decrease in proteolytic (SVMP) activity against azocasein. These results provide the first comparative venomic and anti-venomic analysis of neonate and adult B. irregularis from Guam, further highlighting evolutionary trends in venom composition among rear-fanged venomous snakes. SIGNIFICANCE PARAGRAPH The Brown Treesnake (Boiga irregularis) has caused extensive ecological and economic damage to the island of Guam where it has become a classic example of the negative impacts of invasive species. In the current study, we report the first combined transcriptomic and proteomic analysis of B. irregularis venom of Guam origin. The transcriptome of an adult snake contained toxin sequences belonging to 18 protein families, with three-finger toxin (3FTx) isoforms being the most abundant and representing 94% of all venom protein transcript reads. Our bottom-up and top-down venomic analyses confirmed that 3FTxs are the major components of B. irregularis venom, and a comparative analysis of neonate and adult venoms demonstrate a clear ontogenetic shift in toxin abundance, likely driven by dietary variation between the two age classes. Second-generation antivenomics and Western blot analysis using purified anti-Brown Treesnake rabbit serum IgGs (anti-BTS IgGs) showed strong immunoreactivity toward B. irregularis venom. Interestingly, our anti-BTS IgGs did not cross-react with 3FTxs found in several other rear-fanged snake venoms, or against 3FTxs in the venom of the elapid Ophiophagus hannah, indicating that epitopes in these 3FTx molecules are quite distinct.
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Affiliation(s)
- Davinia Pla
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Daniel Petras
- University of California San Diego, Skaggs School of Pharmacy & Pharmaceutical Sciences, 9500 Gilman Dr, La Jolla, CA 92093, USA
| | - Anthony J Saviola
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain; School of Biological Sciences, University of Northern Colorado, 501 20th Street, CB 92, Greeley, CO 80639, USA
| | - Cassandra M Modahl
- School of Biological Sciences, University of Northern Colorado, 501 20th Street, CB 92, Greeley, CO 80639, USA
| | - Libia Sanz
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Alicia Pérez
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Elena Juárez
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain
| | - Seth Frietze
- School of Biological Sciences, University of Northern Colorado, 501 20th Street, CB 92, Greeley, CO 80639, USA
| | - Pieter C Dorrestein
- University of California San Diego, Skaggs School of Pharmacy & Pharmaceutical Sciences, 9500 Gilman Dr, La Jolla, CA 92093, USA
| | - Stephen P Mackessy
- School of Biological Sciences, University of Northern Colorado, 501 20th Street, CB 92, Greeley, CO 80639, USA.
| | - Juan J Calvete
- Laboratorio de Venómica Estructural y Funcional, Consejo Superior de Investigaciones Científicas, Valencia, Spain.
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Tan KY, Tan CH, Chanhome L, Tan NH. Comparative venom gland transcriptomics of Naja kaouthia (monocled cobra) from Malaysia and Thailand: elucidating geographical venom variation and insights into sequence novelty. PeerJ 2017; 5:e3142. [PMID: 28392982 PMCID: PMC5384570 DOI: 10.7717/peerj.3142] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 03/03/2017] [Indexed: 11/20/2022] Open
Abstract
Background The monocled cobra (Naja kaouthia) is a medically important venomous snake in Southeast Asia. Its venom has been shown to vary geographically in relation to venom composition and neurotoxic activity, indicating vast diversity of the toxin genes within the species. To investigate the polygenic trait of the venom and its locale-specific variation, we profiled and compared the venom gland transcriptomes of N. kaouthia from Malaysia (NK-M) and Thailand (NK-T) applying next-generation sequencing (NGS) technology. Methods The transcriptomes were sequenced on the Illumina HiSeq platform, assembled and followed by transcript clustering and annotations for gene expression and function. Pairwise or multiple sequence alignments were conducted on the toxin genes expressed. Substitution rates were studied for the major toxins co-expressed in NK-M and NK-T. Results and discussion The toxin transcripts showed high redundancy (41–82% of the total mRNA expression) and comprised 23 gene families expressed in NK-M and NK-T, respectively (22 gene families were co-expressed). Among the venom genes, three-finger toxins (3FTxs) predominated in the expression, with multiple sequences noted. Comparative analysis and selection study revealed that 3FTxs are genetically conserved between the geographical specimens whilst demonstrating distinct differential expression patterns, implying gene up-regulation for selected principal toxins, or alternatively, enhanced transcript degradation or lack of transcription of certain traits. One of the striking features that elucidates the inter-geographical venom variation is the up-regulation of α-neurotoxins (constitutes ∼80.0% of toxin’s fragments per kilobase of exon model per million mapped reads (FPKM)), particularly the long-chain α-elapitoxin-Nk2a (48.3%) in NK-T but only 1.7% was noted in NK-M. Instead, short neurotoxin isoforms were up-regulated in NK-M (46.4%). Another distinct transcriptional pattern observed is the exclusively and abundantly expressed cytotoxin CTX-3 in NK-T. The findings suggested correlation with the geographical variation in proteome and toxicity of the venom, and support the call for optimising antivenom production and use in the region. Besides, the current study uncovered full and partial sequences of numerous toxin genes from N. kaouthia which have not been reported hitherto; these include N. kaouthia-specific l-amino acid oxidase (LAAO), snake venom serine protease (SVSP), cystatin, acetylcholinesterase (AChE), hyaluronidase (HYA), waprin, phospholipase B (PLB), aminopeptidase (AP), neprilysin, etc. Taken together, the findings further enrich the snake toxin database and provide deeper insights into the genetic diversity of cobra venom toxins.
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Affiliation(s)
- Kae Yi Tan
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya , Kuala Lumpur , Malaysia
| | - Choo Hock Tan
- Department of Pharmacology, Faculty of Medicine, University of Malaya , Kuala Lumpur , Malaysia
| | | | - Nget Hong Tan
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya , Kuala Lumpur , Malaysia
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12
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de la Rosa G, Pastor N, Alagón A, Corzo G. Synthetic peptide antigens derived from long-chain alpha-neurotoxins: Immunogenicity effect against elapid venoms. Peptides 2017; 88:80-86. [PMID: 28010961 DOI: 10.1016/j.peptides.2016.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 12/12/2016] [Accepted: 12/13/2016] [Indexed: 10/20/2022]
Abstract
Three-finger toxins (3FTXs), especially α-neurotoxins, are the most poorly neutralized elapid snake toxins by current antivenoms. In this work, the conserved structural similarity and motif arrangements of long-chain α-neurotoxins led us to design peptides with consensus sequences. Eight long-chain α-neurotoxins (also known as Type II) were used to generate a consensus sequence from which two peptides were chemically synthesized, LCP1 and LCP2. Rabbit sera raised against them were able to generate partially-neutralizing antibodies, which delayed mice mortality in neutralization assays against Naja haje, Dendrospis polylepis and Ophiophagus hannah venoms.
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Affiliation(s)
- Guillermo de la Rosa
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, Cuernavaca Morelos 61500, Mexico
| | - Nina Pastor
- Centro de Investigación en Dinámica Celular, IICBA, UAEM, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos 62209, Mexico
| | - Alejandro Alagón
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, Cuernavaca Morelos 61500, Mexico
| | - Gerardo Corzo
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, Cuernavaca Morelos 61500, Mexico.
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13
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Dutta S, Chanda A, Kalita B, Islam T, Patra A, Mukherjee AK. Proteomic analysis to unravel the complex venom proteome of eastern India Naja naja: Correlation of venom composition with its biochemical and pharmacological properties. J Proteomics 2017; 156:29-39. [PMID: 28062377 DOI: 10.1016/j.jprot.2016.12.018] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/27/2016] [Accepted: 12/29/2016] [Indexed: 12/29/2022]
Abstract
The complex venom proteome of the eastern India (EI) spectacled cobra (Naja naja) was analyzed using tandem mass spectrometry of cation-exchange venom fractions. About 75% of EI N. naja venom proteins were <18kDa and cationic at physiological pH of blood. SDS-PAGE (non-reduced) analysis indicated that in the native state venom proteins either interacted with each-other or self-aggregated resulting in the formation of higher molecular mass complexes. Proteomic analysis revealed that 43 enzymatic and non-enzymatic proteins in EI N. naja venom with a percent composition of about 28.4% and 71.6% respectively were distributed over 15 venom protein families. The three finger toxins (63.8%) and phospholipase A2s (11.4%) were the most abundant families of non-enzymatic and enzymatic proteins, respectively. nanoLC-ESI-MS/MS analysis demonstrated the occurrence of acetylcholinesterase, phosphodiesterase, cholinesterase and snake venom serine proteases in N. naja venom previously not detected by proteomic analysis. ATPase, ADPase, hyaluronidase, TAME, and BAEE-esterase activities were detected by biochemical analysis; however, due to a limitation in the protein database depository they were not identified in EI N. naja venom by proteomic analysis. The proteome composition of EI N. naja venom was well correlated with its in vitro and in vivo pharmacological properties in experimental animals and envenomed human. BIOLOGICAL SIGNIFICANCE Proteomic analysis reveals the complex and diverse protein profile of EI N. naja venom which collectively contributes to the severe pathophysiological manifestation upon cobra envenomation. The study has also aided in comprehending the compositional variation in venom proteins of N. naja within the Indian sub-continent. In addition, this study has also identified several enzymes in EI N. naja venom which were previously uncharacterized by proteomic analysis of Naja venom.
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McCleary RJR, Sridharan S, Dunstan NL, Mirtschin PJ, Kini RM. Proteomic comparisons of venoms of long-term captive and recently wild-caught Eastern brown snakes (Pseudonaja textilis) indicate venom does not change due to captivity. J Proteomics 2016; 144:51-62. [PMID: 27240975 DOI: 10.1016/j.jprot.2016.05.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/16/2016] [Accepted: 05/24/2016] [Indexed: 01/31/2023]
Abstract
UNLABELLED Snake venom is a highly variable phenotypic character, and its variation and rapid evolution are important because of human health implications. Because much snake antivenom is produced from captive animals, understanding the effects of captivity on venom composition is important. Here, we have evaluated toxin profiles from six long-term (LT) captive and six recently wild-caught (RC) eastern brown snakes, Pseudonaja textilis, utilizing gel electrophoresis, HPLC-MS, and shotgun proteomics. We identified proteins belonging to the three-finger toxins, group C prothrombin activators, Kunitz-type serine protease inhibitors, and phospholipases A2, among others. Although crude venom HPLC analysis showed LT snakes to be higher in some small molecular weight toxins, presence/absence patterns showed no correlation with time in captivity. Shotgun proteomics indicated the presence of similar toxin families among individuals but with variation in protein species. Although no venom sample contained all the phospholipase A2 subunits that form the textilotoxin, all did contain both prothrombin activator subunits. This study indicates that captivity has limited effects on venom composition, that venom variation is high, and that venom composition may be correlated to geographic distribution. BIOLOGICAL SIGNIFICANCE Through proteomic comparisons, we show that protein variation within LT and RC groups of snakes (Pseudonaja textilis) is high, thereby resulting in no discernible differences in venom composition between groups. We utilize complementary techniques to characterize the venom proteomes of 12 individual snakes from our study area, and indicate that individuals captured close to one another have more similar venom gel electrophoresis patterns than those captured at more distant locations. These data are important for understanding natural variation in and potential effects of captivity on venom composition.
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Affiliation(s)
- Ryan J R McCleary
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore; Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA
| | - Sindhuja Sridharan
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore
| | - Nathan L Dunstan
- Venom Supplies Pty. Ltd., P.O. Box 547, Tanunda, South Australia 5352, Australia
| | - Peter J Mirtschin
- Venom Supplies Pty. Ltd., P.O. Box 547, Tanunda, South Australia 5352, Australia
| | - R Manjunatha Kini
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore 117543, Singapore; Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, Singapore 169856, Singapore.
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15
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Modahl CM, Mukherjee AK, Mackessy SP. An analysis of venom ontogeny and prey-specific toxicity in the Monocled Cobra (Naja kaouthia). Toxicon 2016; 119:8-20. [PMID: 27163885 DOI: 10.1016/j.toxicon.2016.04.049] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 04/25/2016] [Accepted: 04/28/2016] [Indexed: 10/21/2022]
Abstract
Venoms of snakes of the family Elapidae (cobras, kraits, mambas, and relatives) are predominantly composed of numerous phospholipases A2 (PLA2s) and three-finger toxins (3FTxs), some of which are lethal while others are not significantly toxic. Currently, the only identified prey-specific toxins are several nonconventional 3FTxs, and given the large diversity of 3FTxs within Monocled Cobra (Naja kaouthia) venom, it was hypothesized that several 3FTxs, previously found to be non-toxic or weakly toxic 3FTxs in murine models, could potentially be toxic towards non-murine prey. Additionally, it was hypothesized that ontogenetic dietary shifts will be correlated with observable changes in specific 3FTx isoform abundance. Adult and juvenile N. kaouthia venom composition was investigated using ion-exchange FPLC, 1D and 2D SDS-PAGE, mass spectrometry, and various enzymatic and LD50 assays. Alpha-cobratoxin (α-elapitoxin) was the only significantly toxic (LD50 < 1 μg/g) 3FTx found in N. kaouthia venom and was equally toxic toward both lizard and mouse models. The abundance and diversity of 3FTxs and most enzyme activities did not vary between adult and juvenile cobra venoms; however, total venom PLA2 activity and specific PLA2 isoforms did vary, with juveniles lacking several of the least acidic PLA2s, and these differences could have both biological (related to predation) and clinical (antivenom efficacy) implications. Nevertheless, the ubiquitous presence of α-cobratoxin in both adult and juvenile cobra venoms, with high toxicity toward both reptiles and mammals, represents a venom compositional strategy wherein a single potent toxin effectively immobilizes a variety of prey types encountered across life history stages.
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Affiliation(s)
- Cassandra M Modahl
- School of Biological Sciences, University of Northern Colorado, 501 20th St., Greeley, CO 80639-0017, USA
| | - Ashis K Mukherjee
- School of Biological Sciences, University of Northern Colorado, 501 20th St., Greeley, CO 80639-0017, USA; Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, 784028 Assam, India
| | - Stephen P Mackessy
- School of Biological Sciences, University of Northern Colorado, 501 20th St., Greeley, CO 80639-0017, USA.
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Tan KY, Tan CH, Fung SY, Tan NH. Venomics, lethality and neutralization of Naja kaouthia (monocled cobra) venoms from three different geographical regions of Southeast Asia. J Proteomics 2015; 120:105-25. [PMID: 25748141 DOI: 10.1016/j.jprot.2015.02.012] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 02/18/2015] [Accepted: 02/24/2015] [Indexed: 01/15/2023]
Abstract
UNLABELLED Previous studies showed that venoms of the monocled cobra, Naja kaouthia from Thailand and Malaysia are substantially different in their median lethal doses. The intraspecific venom variations of N. kaouthia, however, have not been fully elucidated. Here we investigated the venom proteomes of N. kaouthia from Malaysia (NK-M), Thailand (NK-T) and Vietnam (NK-V) through reverse-phase HPLC, SDS-PAGE and tandem mass spectrometry. The venom proteins comprise 13 toxin families, with three-finger toxins being the most abundant (63-77%) and the most varied (11-18 isoforms) among the three populations. NK-T has the highest content of neurotoxins (50%, predominantly long neurotoxins), followed by NK-V (29%, predominantly weak neurotoxins and some short neurotoxins), while NK-M has the least (18%, some weak neurotoxins but less short and long neurotoxins). On the other hand, cytotoxins constitute the main bulk of toxins in NK-M and NK-V venoms (up to 45% each), but less in NK-T venom (27%). The three venoms show different lethal potencies that generally reflect the proteomic findings. Despite the proteomic variations, the use of Thai monovalent and Neuro polyvalent antivenoms for N. kaouthia envenomation in the three regions is appropriate as the different venoms were neutralized by the antivenoms albeit at different degrees of effectiveness. BIOLOGICAL SIGNIFICANCE Biogeographical variations were observed in the venom proteome of monocled cobra (Naja kaouthia) from Malaysia, Thailand and Vietnam. The Thai N. kaouthia venom is particularly rich in long neurotoxins, while the Malaysian and Vietnamese specimens were predominated with cytotoxins. The differentially expressed toxin profile accounts for the discrepancy in the lethal dose of the venom from different populations. Commercially available Thai antivenoms (monovalent and polyvalent) were able to neutralize the three venoms at different effective doses, hence supporting their uses in the three regions. While dose adjustment according to geographical region seems possible, changes to standard recommended dosage should only be made if further study validates that the monocled cobras within a population do not exhibit remarkable inter-individual venom variation.
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Affiliation(s)
- Kae Yi Tan
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Choo Hock Tan
- Department of Pharmacology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; University of Malaya Centre for Proteomics Research (UMPCR), University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Shin Yee Fung
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; University of Malaya Centre for Proteomics Research (UMPCR), University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Nget Hong Tan
- Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia; University of Malaya Centre for Proteomics Research (UMPCR), University of Malaya, 50603 Kuala Lumpur, Malaysia
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Chang HC, Tsai TS, Tsai IH. Functional proteomic approach to discover geographic variations of king cobra venoms from Southeast Asia and China. J Proteomics 2013; 89:141-53. [PMID: 23796489 DOI: 10.1016/j.jprot.2013.06.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/10/2013] [Accepted: 06/13/2013] [Indexed: 11/21/2022]
Abstract
UNLABELLED This study deciphers the geographic variations of king cobra (Ophiophagus hannah) venom using functional proteomics. Pooled samples of king cobra venom (abbreviated as Ohv) were obtained from Indonesia, Malaysia, Thailand, and two provinces of China, namely Guangxi and Hainan. Using two animal models to test and compare the lethal effects, we found that the Chinese Ohvs were more fatal to mice, while the Southeast Asian Ohvs were more fatal to lizards (Eutropis multifasciata). Various phospholipases A2 (PLA2s), three-finger toxins (3FTxs) and Kunitz-type inhibitors were purified from these Ohvs and compared. Besides the two Chinese Ohv PLA2s with known sequences, eight novel PLA2s were identified from the five Ohv samples and their antiplatelet activities were compared. While two 3FTxs (namely oh-55 and oh-27) were common in all the Ohvs, different sets of 3FTx markers were present in the Chinese and Southeast Asian Ohvs. All the Ohvs contain the Kunitz inhibitor, OH-TCI, while only the Chinese Ohvs contain the inhibitor variant, Oh11-1. Relative to the Chinese Ohvs which contained more phospholipases, the Southeast Asian Ohvs had higher metalloproteinase, acetylcholine esterase, and alkaline phosphatase activities. BIOLOGICAL SIGNIFICANCE Remarkable variations in five king cobra geographic samples reveal fast evolution and dynamic translational regulation of the venom which probably adapted to different prey ecology as testified by the lethal tests on mice and lizards. Our results predict possible variations of the king cobra envenoming to human and the importance of using local antivenin for snakebite treatment.
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