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Song YF, Yu LC, Yang MF, Ye S, Yan B, Li LT, Wu C, Liu JF. A Long-Read Genome Assembly of a Native Mite in China Pyemotes zhonghuajia Yu, Zhang & He (Prostigmata: Pyemotidae) Reveals Gene Expansion in Toxin-Related Gene Families. Toxins (Basel) 2022; 14:toxins14080571. [PMID: 36006233 PMCID: PMC9415403 DOI: 10.3390/toxins14080571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/16/2022] [Accepted: 08/17/2022] [Indexed: 11/16/2022] Open
Abstract
Pyemotes zhonghuajia Yu, Zhang & He (Prostigmata: Pyemotidae), discovered in China, has been demonstrated as a high-efficient natural enemy in controlling many agricultural and forestry pests. This mite injects toxins into the host (eggs, larvae, pupae, and adults), resulting in its paralyzation and then gets nourishment for reproductive development. These toxins have been approved to be mammal-safe, which have the potential to be used as biocontrol pesticides. Toxin proteins have been identified from many insects, especially those from the orders Scorpions and Araneae, some of which are now widely used as efficient biocontrol pesticides. However, toxin proteins in mites are not yet understood. In this study, we assembled the genome of P. zhonghuajia using PacBio technology and then identified toxin-related genes that are likely to be responsible for the paralytic process of P. zhonghuajia. The genome assembly has a size of 71.943 Mb, including 20 contigs with a N50 length of 21.248 Mb and a BUSCO completeness ratio of 90.6% (n = 1367). These contigs were subsequently assigned to three chromosomes. There were 11,183 protein coding genes annotated, which were assessed with 91.2% BUSCO completeness (n = 1066). Neurotoxin and dermonecrotic toxin gene families were significantly expanded within the genus of Pyemotes and they also formed several gene clusters on the chromosomes. Most of the genes from these two families and all of the three agatoxin genes were shown with higher expression in the one-day-old mites compared to the seven-day-pregnant mites, supporting that the one-day-old mites cause paralyzation and even death of the host. The identification of these toxin proteins may provide insights into how to improve the parasitism efficiency of this mite, and the purification of these proteins may be used to develop new biological pesticides.
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Affiliation(s)
- Yan-Fei Song
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University, Guiyang 550025, China
- Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Scientific Observing and Experiment Station of Crop Pest Guiyang, Ministry of Agriculture, Guiyang 550025, China
| | - Li-Chen Yu
- Changli Institute of Pomology, Hebei Academy of Agriculture and Forestry Sciences, Changli 066600, China
| | - Mao-Fa Yang
- Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Scientific Observing and Experiment Station of Crop Pest Guiyang, Ministry of Agriculture, Guiyang 550025, China
- College of Tobacco Science, Guizhou University, Guiyang 550025, China
| | - Shuai Ye
- Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Scientific Observing and Experiment Station of Crop Pest Guiyang, Ministry of Agriculture, Guiyang 550025, China
| | - Bin Yan
- Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Scientific Observing and Experiment Station of Crop Pest Guiyang, Ministry of Agriculture, Guiyang 550025, China
| | - Li-Tao Li
- Changli Institute of Pomology, Hebei Academy of Agriculture and Forestry Sciences, Changli 066600, China
| | - Chen Wu
- The New Zealand Institute for Plant and Food Research Limited, Auckland 1142, New Zealand
| | - Jian-Feng Liu
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University, Guiyang 550025, China
- Institute of Entomology, Guizhou University, Guizhou Provincial Key Laboratory for Agricultural Pest Management of the Mountainous Region, Scientific Observing and Experiment Station of Crop Pest Guiyang, Ministry of Agriculture, Guiyang 550025, China
- Correspondence:
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Das B, Saviola AJ, Mukherjee AK. Biochemical and Proteomic Characterization, and Pharmacological Insights of Indian Red Scorpion Venom Toxins. Front Pharmacol 2021; 12:710680. [PMID: 34650430 PMCID: PMC8505525 DOI: 10.3389/fphar.2021.710680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/16/2021] [Indexed: 12/16/2022] Open
Abstract
The Indian red scorpion (Mesobuthus tamulus) is one of the world's deadliest scorpions, with stings representing a life-threatening medical emergency. This species is distributed throughout the Indian sub-continent, including eastern Pakistan, eastern Nepal, and Sri Lanka. In India, Indian red scorpions are broadly distributed in western Maharashtra, Saurashtra, Kerala, Andhra Pradesh, Tamil Nadu, and Karnataka; however, fatal envenomations have been recorded primarily in the Konkan region of Maharashtra. The Indian red scorpion venom proteome comprises 110 proteins belonging to 13 venom protein families. The significant pharmacological activity is predominantly caused by the low molecular mass non-enzymatic Na+ and K+ ion channel toxins. Other minor toxins comprise 15.6% of the total venom proteome. Indian red scorpion stings induce the release of catecholamine, which leads to pathophysiological abnormalities in the victim. A strong correlation has been observed between venom proteome composition and local (swelling, redness, heat, and regional lymph node involvement) and systemic (tachycardia, mydriasis, hyperglycemia, hypertension, toxic myocarditis, cardiac failure, and pulmonary edema) manifestations. Immediate administration of antivenom is the preferred treatment for Indian red scorpion stings. However, scorpion-specific antivenoms have exhibited poor immunorecognition and neutralization of the low molecular mass toxins. The proteomic analysis also suggests that Indian red scorpion venom is a rich source of pharmacologically active molecules that may be envisaged as drug prototypes. The following review summarizes the progress made towards understanding the venom proteome of the Indian red scorpion and addresses the current understanding of the pathophysiology associated with its sting.
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Affiliation(s)
- Bhabana Das
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
| | - Anthony J. Saviola
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Ashis K. Mukherjee
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
- Institute of Advanced Study in Science and Technology, Guwahati, India
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Zhu S, Gao B, Peigneur S, Tytgat J. How a Scorpion Toxin Selectively Captures a Prey Sodium Channel: The Molecular and Evolutionary Basis Uncovered. Mol Biol Evol 2021; 37:3149-3164. [PMID: 32556211 DOI: 10.1093/molbev/msaa152] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The growing resistance of insects to chemical pesticides is reducing the effectiveness of conventional methods for pest control and thus, the development of novel insecticidal agents is imperative. Scorpion toxins specific for insect voltage-gated sodium channels (Navs) have been considered as one of the most promising insecticide alternatives due to their host specificity, rapidly evoked toxicity, biodegradability, and the lack of resistance. However, they have not been developed for uses in agriculture and public health, mainly because of a limited understanding of their molecular and evolutionary basis controlling their phylogenetic selectivity. Here, we show that the traditionally defined insect-selective scorpion toxin LqhIT2 specifically captures a prey Nav through a conserved trapping apparatus comprising a three-residue-formed cavity and a structurally adjacent leucine. The former serves as a detector to recognize and bind a highly exposed channel residue conserved in insects and spiders, two major prey items for scorpions; and the latter subsequently seizes the "moving" voltage sensor via hydrophobic interactions to reduce activation energy for channel opening, demonstrating its action in an enzyme-like manner. Based on the established toxin-channel interaction model in combination with toxicity assay, we enlarged the toxic spectrum of LqhIT2 to spiders and certain other arthropods. Furthermore, we found that genetic background-dependent cavity shapes determine the species selectivity of LqhIT2-related toxins. We expect that the discovery of the trapping apparatus will improve our understanding of the evolution and design principle of Nav-targeted toxins from a diversity of arthropod predators and accelerate their uses in pest control.
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Affiliation(s)
- Shunyi Zhu
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Bin Gao
- Group of Peptide Biology and Evolution, State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Steve Peigneur
- Department of Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Jan Tytgat
- Department of Toxicology and Pharmacology, University of Leuven (KU Leuven), Leuven, Belgium
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Li H, Xia Y. High-level expression and purification of active scorpion long-chain neurotoxin BjαIT from Pichia pastoris. Protein Expr Purif 2018; 152:77-83. [PMID: 30071250 DOI: 10.1016/j.pep.2018.07.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/06/2018] [Accepted: 07/27/2018] [Indexed: 12/13/2022]
Abstract
As an insect-selective neurotoxin, scorpion long-chain BjαIT is a promising prospect for insecticidal application; however, the difficulty of obtaining natural BjαIT represents the major obstacle preventing analysis of its insecticidal activity against agricultural insect pests. Here, we screened recombinant Pichia pastoris transformants showing high levels of secretory recombinant (r)BjαIT. Secreted rBjαIT was expressed at levels as high as 340 mg/L following methanol induction in a fed-batch reactor, with ∼21 mg of pure rBjαIT obtained from 200-mL fed-batch culture supernatant by Ni2+-nitriloacetic acid affinity chromatography and CM Sepharose ion-exchange chromatography. Injection of purified rBjαIT induced neurotoxicity symptoms in locust (Locusta migratoria) larvae, and the half-lethal dose of rBjαIT for locusts at 24-h post-injection ranged from 11 to 14 μg/g body weight. These results demonstrated that large amounts of active rBjαIT were efficiently prepared from P. pastoris, suggesting this system as efficacious for determining rBjαIT insecticidal activity against other agricultural insect pests.
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Affiliation(s)
- Hongbo Li
- Postdoctoral Mobile Station of Biology, Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing, 400030, China; The Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, College of Biological and Food Engineering, Huaihua University, Huaihua, 418008, China
| | - Yuxian Xia
- Postdoctoral Mobile Station of Biology, Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing, 400030, China.
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Li H, Xia Y. Improving the secretory expression of active recombinant AaIT in Pichia pastoris by changing the expression strain and plasmid. World J Microbiol Biotechnol 2018; 34:104. [PMID: 29951705 DOI: 10.1007/s11274-018-2484-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/16/2018] [Indexed: 11/28/2022]
Abstract
Scorpion long-chain insect selective neurotoxin AaIT has the potential to be used against agricultural insect pests. However, there is still a lack of a heterologous gene expression system that can express AaIT efficiently. Here, using X33 as the host strain and pPICZαA as the expression vector, one transformant had the highest expression of recombinant AaIT (rAaIT) was obtained, and secreted as high as 240 mg/l rAaIT in fed-batch fermentation. Secretory rAaIT was purified by Ni2+-nitriloacetic affinity and CM chromatography, and 8 mg of high purity rAaIT were purified from 200 ml fed-batch fermentation cultures. Injecting silkworm (Bombyx mori Linnaeus) and Galleria mellonella larvae with rAaIT resulted in obvious neurotoxin symptoms and led to death. These results demonstrate that a large amount of anti-insect active rAaIT could be prepared efficiently.
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Affiliation(s)
- Hongbo Li
- Postdoctoral Mobile Station of Biology, Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing, 400030, China. .,The Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, College of Biological and Food Engineering, Huaihua University, Huaihua, 418008, China.
| | - Yuxian Xia
- Postdoctoral Mobile Station of Biology, Genetic Engineering Research Center, College of Life Sciences, Chongqing University, Chongqing, 400030, China.
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Abstract
Voltage-gated sodium channels (VGSCs) are critical in generation and conduction of electrical signals in multiple excitable tissues. Natural toxins, produced by animal, plant, and microorganisms, target VGSCs through diverse strategies developed over millions of years of evolutions. Studying of the diverse interaction between VGSC and VGSC-targeting toxins has been contributing to the increasing understanding of molecular structure and function, pharmacology, and drug development potential of VGSCs. This chapter aims to summarize some of the current views on the VGSC-toxin interaction based on the established receptor sites of VGSC for natural toxins.
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Affiliation(s)
- Yonghua Ji
- Laboratory of Neuropharmacology and Neurotoxicology, Shanghai University, Shanghai, China.
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β/δ-PrIT1, a highly insecticidal toxin from the venom of the Brazilian spider Phoneutria reidyi (F.O. Pickard-Cambridge, 1897). Toxicon 2015. [DOI: 10.1016/j.toxicon.2015.07.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Trancriptomic approach reveals the molecular diversity of Hottentotta conspersus (Buthidae) venom. Toxicon 2015; 99:73-9. [DOI: 10.1016/j.toxicon.2015.03.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 03/20/2015] [Accepted: 03/25/2015] [Indexed: 11/21/2022]
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Tianpei X, Li D, Qiu P, Luo J, Zhu Y, Li S. Scorpion peptide LqhIT2 activates phenylpropanoid pathways via jasmonate to increase rice resistance to rice leafrollers. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2015; 230:1-11. [PMID: 25480003 DOI: 10.1016/j.plantsci.2014.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 10/07/2014] [Accepted: 10/09/2014] [Indexed: 05/09/2023]
Abstract
LqhIT2 is an insect-specific toxin peptide identified in Leiurus quinquestriatus hebraeus that can be toxic to lepidoptera pests. However, whether LqhIT2 induces insect resistance in rice, and how the LqhIT2 influences the biochemical metabolism of rice plants remains unknown. Here, purified LqhIT2-GST fusion protein had toxicity to rice leafrollers. Meanwhile, in vitro and field trials showed that LqhIT2 transgenic rice plants were less damaged by rice leafrollers compared to the wild type plants. Introducing LqhIT2 primed the elevated expression of lipoxygenase, a key component of the jasmonic acid biosynthetic pathway, together with enhanced linolenic acid, cis-(+)-12-oxophytodienoic acid, jasmonic acid, and jasmonic acid-isoleucine levels. In addition, phenylalanine ammonia-lyase, a key gene of the phenylpropanoid pathway, was up-regulated. Correspondingly, the contents of downstream products of the phenylpropanoid pathway such as flavonoids and lignins, were also increased in LqhIT2 transgenic plants. These changes were paralleled by decreased starch, glucose, and glucose-6-phosphate accumulation, the key metabolites of glycolysis pathway that supplies the raw material and intermediate carbon products for phenylpropanoids biosyntheses. These findings suggest that, in addition to its own toxicity against pests, LqhIT2 activate the phenylpropanoid pathway via jasmonate-mediated priming, which subsequently increases flavonoid and lignin content and improves insect resistance in rice.
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Affiliation(s)
- Xiuzi Tianpei
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of the Ministry of Agriculture, Engineering Research Center for Plant Biotechology and Germplasm Utilization of the Ministry of Education, College of Life Science, Wuhan University, Wuhan 430072, China
| | - Dong Li
- National Key Laboratory of Genetic Crop Improvement, Huazhong Agriculture University, Wuhan 430070, China
| | - Ping Qiu
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of the Ministry of Agriculture, Engineering Research Center for Plant Biotechology and Germplasm Utilization of the Ministry of Education, College of Life Science, Wuhan University, Wuhan 430072, China
| | - Jie Luo
- National Key Laboratory of Genetic Crop Improvement, Huazhong Agriculture University, Wuhan 430070, China.
| | - Yingguo Zhu
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of the Ministry of Agriculture, Engineering Research Center for Plant Biotechology and Germplasm Utilization of the Ministry of Education, College of Life Science, Wuhan University, Wuhan 430072, China
| | - Shaoqing Li
- State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of the Ministry of Agriculture, Engineering Research Center for Plant Biotechology and Germplasm Utilization of the Ministry of Education, College of Life Science, Wuhan University, Wuhan 430072, China.
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Peng G, Xia Y. Expression of scorpion toxin LqhIT2 increases the virulence of Metarhizium acridum towards Locusta migratoria manilensis. J Ind Microbiol Biotechnol 2014; 41:1659-66. [PMID: 25168679 DOI: 10.1007/s10295-014-1497-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 08/12/2014] [Indexed: 01/24/2023]
Abstract
LqhIT2 is an insect-specific neurotoxin from the venom of scorpion. In this study, the LqhIT2 gene was introduced into the entomopathogenic fungus, Metarhizium acridum. The virulence of the genetically modified strain MaLqhIT2 was then evaluated against locusts (Locusta migratoria manilensis). Compared with the wild-type strain, the median lethal cell density (LC50) for MaLqhIT2 was a 22.6-fold lower, and the median times to death (LT50) for MaLqhIT2 were reduced by 30.3 and 29.6 %, respectively, after topical inoculation and injection. MaLqhIT2 also grew significantly faster in the hemolymph than wild-type strain. There were no significant differences in germination, appressorium formation and sporulation in locust carcasses between the MaLqhIT2 and wild-type strain. These results indicate that LqhIT2 increased the virulence of M. acridum towards locusts by shortening the in vivo infection period, without affecting cuticle penetration or conidia formation in the carcasses. LqhIT2 thus shows considerable potential for increasing fungal virulence against locusts.
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Affiliation(s)
- Guoxiong Peng
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, 174# shazheng st., Shangpingba District, Chongqing, 400030, China,
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Arzamasov AA, Vassilevski AA, Grishin EV. Chlorotoxin and related peptides: Short insect toxins from scorpion venom. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2014; 40:387-98. [DOI: 10.1134/s1068162014040013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Tianpei X, Zhu Y, Li S. Optimized scorpion polypeptide LMX: a pest control protein effective against rice leaf folder. PLoS One 2014; 9:e100232. [PMID: 24964088 PMCID: PMC4070919 DOI: 10.1371/journal.pone.0100232] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 05/24/2014] [Indexed: 11/25/2022] Open
Abstract
Lepidopteran insect pests are the main class of pests causing significant damage to crop plant yields. Insecticidal scorpion peptides exhibit toxicity specific for insects. Here, we report that a peptide LMX, optimized from the insect-specific scorpion neurotoxin LqhIT2, showed high levels of activity against rice leaf folder in vitro and in planta. Oral ingestion of LMX protein led to a significant decrease in feeding on rice leaves, repression of larval growth and development, delay in molting, and increase in larval lethality. Compared with LqhIT2 protein, the stability and insecticidal efficacy of LMX was better. Meanwhile, biochemical analysis showed that LMX protein ingestion dramatically decreased ecdysone content in rice leaf folder larvae, and down-regulated enzymatic activities of the detoxification system (α-naphthyl acetate esterase and glutathione S-transferase), the digestive system (tryptase and chymotrypsin), and the antioxidant system (catalase). These changes were tightly correlated with the dosage of LMX protein. Transgene analysis showed that the rate of leaf damage, and the number of damaged tillers and leaves in the transgenic line were greatly reduced relative to wild type plants and empty vector plants. Based on these observations, we propose that the insect-specific scorpion neurotoxin peptide LMX is an attractive and effective alternative molecule for the protection of rice from rice leaf folder.
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Affiliation(s)
- Xiuzi Tianpei
- State Key Laboratory of Hybrid Rice; Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture; Engineering Research Center for Plant Biotechology and Germplasm Utilization of Ministry of Education; College of Life Sciences, Wuhan University, Wuhan, China
| | - Yingguo Zhu
- State Key Laboratory of Hybrid Rice; Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture; Engineering Research Center for Plant Biotechology and Germplasm Utilization of Ministry of Education; College of Life Sciences, Wuhan University, Wuhan, China
| | - Shaoqing Li
- State Key Laboratory of Hybrid Rice; Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture; Engineering Research Center for Plant Biotechology and Germplasm Utilization of Ministry of Education; College of Life Sciences, Wuhan University, Wuhan, China
- * E-mail:
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Mille BG, Peigneur S, Diego-García E, Predel R, Tytgat J. Partial transcriptomic profiling of toxins from the venom gland of the scorpion Parabuthus stridulus. Toxicon 2014; 83:75-83. [DOI: 10.1016/j.toxicon.2014.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 02/05/2014] [Accepted: 03/04/2014] [Indexed: 01/02/2023]
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Two peptides, TsAP-1 and TsAP-2, from the venom of the Brazilian yellow scorpion, Tityus serrulatus: evaluation of their antimicrobial and anticancer activities. Biochimie 2013; 95:1784-94. [PMID: 23770440 DOI: 10.1016/j.biochi.2013.06.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/05/2013] [Indexed: 11/21/2022]
Abstract
Here we report two novel 17-mer amidated linear peptides (TsAP-1 and TsAP-2) whose structures were deduced from cDNAs cloned from a venom-derived cDNA library of the Brazilian yellow scorpion, Tityus serrulatus. Both mature peptides were structurally-characterised following their location in chromatographic fractions of venom and synthetic replicates of each were subjected to a range of biological assays. The peptides were each active against model test micro-organisms but with different potencies. TsAP-1 was of low potency against all three test organisms (MICs 120-160 μM), whereas TsAP-2 was of high potency against the Gram-positive bacterium, Staphylococcus aureus (MIC 5 μM) and the yeast, Candida albicans (10 μM). Haemolytic activity of TsAP-1 was low (4% at 160 μM) and in contrast, that of TsAP-2 was considerably higher (18% at 20 μM). Substitution of four neutral amino acid residues with Lys residues in each peptide had dramatic effects on their antimicrobial potencies and haemolytic activities, particularly those of TsAP-1. The MICs of the enhanced cationic analogue (TsAP-S1) were 2.5 μM for S. aureus/C. albicans and 5 μM for E. coli but with an associated large increase in haemolytic activity (30% at 5 μM). The same Lys residue substitutions in TsAP-2 produced a dramatic effect on its MIC for E. coli lowering this from >320 μM to 5 μM. TsAP-1 was ineffective against three of the five human cancer cell lines tested while TsAP-2 inhibited the growth of all five. Lys residue substitution of both peptides enhanced their potency against all five cell lines with TsAp-S2 being the most potent with IC50 values ranging between 0.83 and 2.0 μM. TsAP-1 and TsAP-2 are novel scorpion venom peptides with broad spectrum antimicrobial and anticancer cell activities the potencies of which can be significantly enhanced by increasing their cationicity.
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Gurevitz M. Mapping of scorpion toxin receptor sites at voltage-gated sodium channels. Toxicon 2012; 60:502-11. [DOI: 10.1016/j.toxicon.2012.03.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 03/22/2012] [Accepted: 03/27/2012] [Indexed: 10/28/2022]
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Schwartz EF, Mourão CBF, Moreira KG, Camargos TS, Mortari MR. Arthropod venoms: A vast arsenal of insecticidal neuropeptides. Biopolymers 2012. [DOI: 10.1002/bip.22100] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Abstract
Synopsis:The diversity of biological functions that are exerted by toxins from snake and scorpion venoms is associated with a limited number of structural frameworks. At present, one predominant basic fold has been observed among scorpion toxins whereas six folds have been found among snake toxins. Most toxin folds have the capacity to accept multiple insertions, deletions and mutations and to exert various recognition functions. We suggest that such folds may serve as guides to engineer new protein functions.
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Stevens M, Peigneur S, Tytgat J. Neurotoxins and their binding areas on voltage-gated sodium channels. Front Pharmacol 2011; 2:71. [PMID: 22084632 PMCID: PMC3210964 DOI: 10.3389/fphar.2011.00071] [Citation(s) in RCA: 179] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 10/24/2011] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are large transmembrane proteins that conduct sodium ions across the membrane and by doing so they generate signals of communication between many kinds of tissues. They are responsible for the generation and propagation of action potentials in excitable cells, in close collaboration with other channels like potassium channels. Therefore, genetic defects in sodium channel genes can cause a wide variety of diseases, generally called “channelopathies.” The first insights into the mechanism of action potentials and the involvement of sodium channels originated from Hodgkin and Huxley for which they were awarded the Nobel Prize in 1963. These concepts still form the basis for understanding the function of VGSCs. When VGSCs sense a sufficient change in membrane potential, they are activated and consequently generate a massive influx of sodium ions. Immediately after, channels will start to inactivate and currents decrease. In the inactivated state, channels stay refractory for new stimuli and they must return to the closed state before being susceptible to a new depolarization. On the other hand, studies with neurotoxins like tetrodotoxin (TTX) and saxitoxin (STX) also contributed largely to our today’s understanding of the structure and function of ion channels and of VGSCs specifically. Moreover, neurotoxins acting on ion channels turned out to be valuable lead compounds in the development of new drugs for the enormous range of diseases in which ion channels are involved. A recent example of a synthetic neurotoxin that made it to the market is ziconotide (Prialt®, Elan). The original peptide, ω-MVIIA, is derived from the cone snail Conus magus and now FDA/EMA-approved for the management of severe chronic pain by blocking the N-type voltage-gated calcium channels in pain fibers. This review focuses on the current status of research on neurotoxins acting on VGSC, their contribution to further unravel the structure and function of VGSC and their potential as novel lead compounds in drug development.
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Affiliation(s)
- Marijke Stevens
- Lab of Toxicology, Katholieke Universiteit Leuven Leuven, Belgium
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19
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Abdel-Rahman MA, Omran MAA, Abdel-Nabi IM, Nassier OA, Schemerhorn BJ. Neurotoxic and cytotoxic effects of venom from different populations of the Egyptian Scorpio maurus palmatus. Toxicon 2009; 55:298-306. [PMID: 19682484 DOI: 10.1016/j.toxicon.2009.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 07/31/2009] [Accepted: 08/05/2009] [Indexed: 10/20/2022]
Abstract
Neurotoxic and cytotoxic effects of venoms from Scorpio maurus palmatus taken from different populations were assessed for geographic based variability in toxicity, and to evaluate their insecticidal potency. Scorpions were collected from four regions. Three locations were mutually isolated pockets in the arid area of Southern Sinai. The fourth sample was collected from a population inhabiting the semi-arid environment of Western Mediterranean Coastal Desert. The neurotoxic (paralytic) effect of the venom from each population was assayed by its ability to induce permanent disability in adult cockroaches within 3h. Venom was applied using microinjection techniques through an intersegmental membrane. Probit analysis was used to calculate the Paralytic Effective Dose (PED(50), ng/100mg). Levels of glutathione, lipid peroxidation, protein carbonyl content and nitric oxide, as well as the activities of superoxide dismutase, catalase and cholinesterase, were measured to assess the cytotoxicity of the venom. The results show that the injected venom from each population induced obvious spasticity, followed by flaccid paralysis. All the tested biochemical parameters, except glutathione content, revealed significant differences in toxicity in venom taken from the different scorpion populations. We conclude that (i) the venom of this scorpion has significant neurotoxic and cytotoxic effects on insect cells, (ii) its efficacy, as assessed by the PED(50) unit, exhibited variation across its geographic range, and (iii) components in the venom may have the potential for being developed into effective and environmentally friendly bioinsecticides.
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Affiliation(s)
- Mohamed A Abdel-Rahman
- Department of Zoology, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.
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Gordon D, Savarin P, Gurevitz M, Zinn-Justin S. Functional Anatomy of Scorpion Toxins Affecting Sodium Channels. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/15569549809009247] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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21
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Li H, Xia Y. High expression and rapid purification of recombinant scorpion anti-insect neurotoxin AaIT. World J Microbiol Biotechnol 2009. [DOI: 10.1007/s11274-009-0009-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Corzo G, Bernard C, Clement H, Villegas E, Bosmans F, Tytgat J, Possani LD, Darbon H, Alagón A. Insecticidal peptides from the theraposid spider Brachypelma albiceps: an NMR-based model of Ba2. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1190-6. [PMID: 19374957 DOI: 10.1016/j.bbapap.2009.04.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 04/01/2009] [Accepted: 04/06/2009] [Indexed: 11/16/2022]
Abstract
Soluble venom and purified fractions of the theraposid spider Brachypelma albiceps were screened for insecticidal peptides based on toxicity to crickets. Two insecticidal peptides, named Ba1 and Ba2, were obtained after the soluble venom was separated by high performance liquid chromatography and cation exchange chromatography. The two insecticidal peptides contain 39 amino acid residues and three disulfide bonds, and based on their amino acid sequence, they are highly identical to the insecticidal peptides from the theraposid spiders Aphonopelma sp. from the USA and Haplopelma huwenum from China indicating a relationship among these genera. Although Ba1 and Ba2 were not able to modify currents in insect and vertebrate cloned voltage-gated sodium ion channels, they have noteworthy insecticidal activities compared to classical arachnid insecticidal toxins indicating that they might target unknown receptors in insect species. The most abundant insecticidal peptide Ba2 was submitted to NMR spectroscopy to determine its 3-D structure; a remarkable characteristic of Ba2 is a cluster of basic residues, which might be important for receptor recognition.
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Affiliation(s)
- Gerardo Corzo
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Cuernavaca, Morelos, Mexico.
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23
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Zlotkin E, Eitan M, Pelhate M, Chejanovsky N, Gurevitz M, Gordon D. Insect Specific Neurotoxins from Scorpion Venom that Affect Sodium Current Inactivation. ACTA ACUST UNITED AC 2008. [DOI: 10.3109/15569549409006479] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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24
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Becerril B, Corona M, García C, Bolívar F, Possani LD. Cloning of Genes Encoding Scorpion Toxins: An Interpretative Review. ACTA ACUST UNITED AC 2008. [DOI: 10.3109/15569549509019468] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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25
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Jeffers LA, Michael Roe R. The movement of proteins across the insect and tick digestive system. JOURNAL OF INSECT PHYSIOLOGY 2008; 54:319-332. [PMID: 18177888 DOI: 10.1016/j.jinsphys.2007.10.009] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 10/20/2007] [Accepted: 10/22/2007] [Indexed: 05/25/2023]
Abstract
The movement of intact proteins across the digestive system was shown in a number of different blood-feeding and non-blood-feeding insects in the orders Blattaria, Coleoptera, Diptera, Hemiptera, Lepidoptera, Orthoptera, Neuroptera and Siphonaptera, as well as in two tick families Ixodidae and Argasidae. Protein movement was observed for both normal dietary and xenobiotic proteins, which suggest that the mechanism for transfer is not substrate specific. The number of studies on the mechanism of movement is limited. The research so far suggests that movement can occur by either a transcellular or an intercellular pathway in the ventriculus with most of the research describing the former. Transfer is by continuous diffusion with no evidence of pinocytosis or vesicular transport common in mammalian systems. Proteins can move across the digestive system without modification of their primary or multimeric structure and with retention of their functional characteristics. Accumulation in the hemolymph is the result of the protein degradation rate in the gut and hemolymph and transfer rate across the digestive system and can be highly variable depending on species. Research on the development of delivery systems to enhance protein movement across the insect digestive system is in its infancy. The approaches so far considered with some success include the use of lipophilic-polyethylene glycol (PEG) polymers, the development of fusion proteins with lectins, reduced gut protease activity and the development of amphiphilic peptidic analogs. Additional research on understanding the basic mechanisms of protein delivery across the insect digestive system, the importance of structure activity in this transfer and the development of technology to improve movement across the gut could be highly significant to the future of protein and nucleic acid-based insecticide development as well as traditional chemical insecticidal technologies.
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Affiliation(s)
- Laura A Jeffers
- Department of Entomology, Dearstyne Entomology Building, North Carolina State University, Raleigh, NC 27695-7647, USA
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26
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Cohen L, Troub Y, Turkov M, Gilles N, Ilan N, Benveniste M, Gordon D, Gurevitz M. Mammalian Skeletal Muscle Voltage-Gated Sodium Channels Are Affected by Scorpion Depressant “Insect-Selective” Toxins when Preconditioned. Mol Pharmacol 2007; 72:1220-7. [PMID: 17720763 DOI: 10.1124/mol.107.039057] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Among scorpion beta- and alpha-toxins that modify the activation and inactivation of voltage-gated sodium channels (Na(v)s), depressant beta-toxins have traditionally been classified as anti-insect selective on the basis of toxicity assays and lack of binding and effect on mammalian Na(v)s. Here we show that the depressant beta-toxins LqhIT2 and Lqh-dprIT3 from Leiurus quinquestriatus hebraeus (Lqh) bind with nanomolar affinity to receptor site 4 on rat skeletal muscle Na(v)s, but their effect on the gating properties can be viewed only after channel preconditioning, such as that rendered by a long depolarizing prepulse. This observation explains the lack of toxicity when depressant toxins are injected in mice. However, when the muscle channel rNa(v)1.4, expressed in Xenopus laevis oocytes, was modulated by the site 3 alpha-toxin LqhalphaIT, LqhIT2 was capable of inducing a negative shift in the voltage-dependence of activation after a short prepulse, as was shown for other beta-toxins. These unprecedented results suggest that depressant toxins may have a toxic impact on mammals in the context of the complete scorpion venom. To assess whether LqhIT2 and Lqh-dprIT3 interact with the insect and rat muscle channels in a similar manner, we examined the role of Glu24, a conserved "hot spot" at the bioactive surface of beta-toxins. Whereas substitutions E24A/N abolished the activity of both LqhIT2 and Lqh-dprIT3 at insect Na(v)s, they increased the affinity of the toxins for rat skeletal muscle channels. This result implies that depressant toxins interact differently with the two channel types and that substitution of Glu24 is essential for converting toxin selectivity.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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27
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De Lima ME, Figueiredo SG, Pimenta AMC, Santos DM, Borges MH, Cordeiro MN, Richardson M, Oliveira LC, Stankiewicz M, Pelhate M. Peptides of arachnid venoms with insecticidal activity targeting sodium channels. Comp Biochem Physiol C Toxicol Pharmacol 2007; 146:264-279. [PMID: 17218159 DOI: 10.1016/j.cbpc.2006.10.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 10/19/2006] [Accepted: 10/21/2006] [Indexed: 12/18/2022]
Abstract
Arachnids have a venom apparatus and secrete a complex chemical mixture of low molecular mass organic molecules, enzymes and polypeptide neurotoxins designed to paralyze or kill their prey. Most of these toxins are specific for membrane voltage-gated sodium channels, although some may also target calcium or potassium channels and other membrane receptors. Scorpions and spiders have provided the greatest number of the neurotoxins studied so far, for which, a good number of primary and 3D structures have been obtained. Structural features, comprising a folding that determines a similar spatial distribution of charged and hydrophobic side chains of specific amino acids, are strikingly common among the toxins from spider and scorpion venoms. Such similarities are, in turn, the key feature to target and bind these proteins to ionic channels. The search for new insecticidal compounds, as well as the study of their modes of action, constitutes a current approach to rationally design novel insecticides. This goal tends to be more relevant if the resistance to the conventional chemical products is considered. A promising alternative seems to be the biotechnological approach using toxin-expressing recombinant baculovirus. Spider and scorpion toxins having insecticidal activity are reviewed here considering their structures, toxicities and action mechanisms in sodium channels of excitable membranes.
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Affiliation(s)
- M E De Lima
- Lab. Venenos e Toxinas Animais, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil; Núcleo de Biomoléculas - Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil.
| | - S G Figueiredo
- Centro de Ciências Fisiológicas, CBM - Universidade Federal do Espírito Santo, Vitória, ES, Brasil
| | - A M C Pimenta
- Lab. Venenos e Toxinas Animais, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil; Núcleo de Biomoléculas - Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil
| | - D M Santos
- Lab. Venenos e Toxinas Animais, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil; Núcleo de Biomoléculas - Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil
| | - M H Borges
- Lab. Venenos e Toxinas Animais, Universidade Federal de Minas Gerais, 31.270-901, Belo Horizonte, MG, Brasil; Centro de Pesquisa Prof. Carlos R. Diniz, Fundação Ezequiel Dias, Belo Horizonte, MG, Brasil
| | - M N Cordeiro
- Centro de Pesquisa Prof. Carlos R. Diniz, Fundação Ezequiel Dias, Belo Horizonte, MG, Brasil
| | - M Richardson
- Centro de Pesquisa Prof. Carlos R. Diniz, Fundação Ezequiel Dias, Belo Horizonte, MG, Brasil
| | - L C Oliveira
- Departamento de Farmácia Bioquímica - Universidade Federal dos Vales do Jequitinhonha e Mucuri, 39100-000, Diamantina, MG, Brasil
| | - M Stankiewicz
- Laboratory of Biophysics - Institute of General and Molecular Biology, N. Copernicus University, 87-100, Torun, Poland
| | - M Pelhate
- Lab. Récepteurs et Canaux Ioniques Membranaires, Université d'Angers, 49045, Angers, France
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28
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Miyashita M, Otsuki J, Hanai Y, Nakagawa Y, Miyagawa H. Characterization of peptide components in the venom of the scorpion Liocheles australasiae (Hemiscorpiidae). Toxicon 2007; 50:428-37. [PMID: 17559900 DOI: 10.1016/j.toxicon.2007.04.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Revised: 04/09/2007] [Accepted: 04/10/2007] [Indexed: 11/25/2022]
Abstract
Scorpion venoms are composed of a number of neurotoxic peptides. A variety of toxins have been isolated from the venoms of scorpions of the family Buthidae, however, little interest has been paid to non-Buthidae scorpions. In this study, we examined the toxicity of the venom of Liocheles australasiae (Hemiscorpiidae) to mice and crickets, and characterized the peptide components by HPLC and mass spectrometry. Over 200 components were detected in the L. australasiae venom by LC/MS analysis, with components of molecular masses ranging from 500 to 5000 Da being particularly abundant. A number of peptides contained two to four disulfide bridges, which was estimated based on the mass difference after derivatization of Cys residues. A peptide having a monoisotopic molecular mass of 7781.6 Da and four disulfide bridges was isolated from the venom. The peptide has a primary structure similar in terms of the position of eight Cys residues to those observed in several peptides found from scorpions, ticks and insects, although biological roles of these peptides are unknown.
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Affiliation(s)
- Masahiro Miyashita
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
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29
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Gurevitz M, Karbat I, Cohen L, Ilan N, Kahn R, Turkov M, Stankiewicz M, Stühmer W, Dong K, Gordon D. The insecticidal potential of scorpion β-toxins. Toxicon 2007; 49:473-89. [PMID: 17197009 DOI: 10.1016/j.toxicon.2006.11.015] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 11/20/2006] [Indexed: 11/28/2022]
Abstract
Voltage-gated sodium channels are a major target for toxins and insecticides due to their central role in excitability, but due to the conservation of these channels in Animalia most insecticides do not distinguish between those of insects and mammals, thereby imposing risks to humans and livestock. Evidently, as long as modern agriculture depends heavily on the use of insecticides there is a great need for new substances capable of differentiating between sodium channel subtypes. Such substances exist in venomous animals, but ways for their exploitation have not yet been developed due to problems associated with manufacturing, degradation, and delivery to the target channels. Engineering of plants for expression of anti-insect toxins or use of natural vectors that express toxins near their target site (e.g. baculoviruses) are still problematic and raise public concern. In this problematic reality a rational approach might be to learn from nature how to design highly selective anti-insect compounds preferably in the form of peptidomimetics. This is a complex task that requires the elucidation of the face of interaction between insect-selective toxins and their sodium channel receptor sites. This review delineates current progress in: (i) elucidation of the bioactive surfaces of scorpion beta-toxins, especially the excitatory and depressant groups, which show high preference for insects and bind insect sodium channels with high affinity; (ii) studies of the mode of interaction of scorpion beta-toxins with receptor site-4 on voltage-gated sodium channels; and (iii) clarification of channel elements that constitute receptor site-4. This information may be useful in future attempts to mimic the bioactive surface of the toxins for the design of anti-insect selective peptidomimetics.
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Affiliation(s)
- Michael Gurevitz
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel.
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de la Vega RCR, Possani LD. Novel paradigms on scorpion toxins that affects the activating mechanism of sodium channels. Toxicon 2007; 49:171-80. [PMID: 17081580 DOI: 10.1016/j.toxicon.2006.09.016] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Scorpion toxins classified as beta-class are reviewed using a new paradigm. Four distinct sub types are recognized: "classical", "Tsgamma-like", "excitatory" and "depressant"beta-scorpion toxins. Recent experimental data have made possible to identify the interacting interfaces of the Na(+) channel-receptor site 4 with some of these toxins. The voltage-sensor trapping mechanism proposed for the action of these toxic peptides is analyzed in the context of what causes a modification of the activating mechanism of Na(+) channels. A cartoon model is presented with the purpose of summarizing the most current knowledge on the field. Finally, the recent advances on the knowledge of the specific interactions of beta-toxins and different sub types of Na(+) channels are also reviewed.
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Affiliation(s)
- Ricardo C Rodríguez de la Vega
- Department of Molecular Medicine and Bioprocesses, Institute of Biotechnology, National Autonomous University of Mexico, Av. Universidad 2001, Cuernavaca Morelos 62210, México.
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31
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Karbat I, Turkov M, Cohen L, Kahn R, Gordon D, Gurevitz M, Frolow F. X-ray structure and mutagenesis of the scorpion depressant toxin LqhIT2 reveals key determinants crucial for activity and anti-insect selectivity. J Mol Biol 2006; 366:586-601. [PMID: 17166514 DOI: 10.1016/j.jmb.2006.10.085] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Revised: 10/23/2006] [Accepted: 10/25/2006] [Indexed: 10/23/2022]
Abstract
Scorpion depressant beta-toxins show high preference for insect voltage-gated sodium channels (Na(v)s) and modulate their activation. Although their pharmacological and physiological effects were described, their three-dimensional structure and bioactive surface have never been determined. We utilized an efficient system for expression of the depressant toxin LqhIT2 (from Leiurus quinquestriatushebraeus), mutagenized its entire exterior, and determined its X-ray structure at 1.2 A resolution. The toxin molecule is composed of a conserved cysteine-stabilized alpha/beta-core (core-globule), and perpendicular to it an entity constituted from the N and C-terminal regions (NC-globule). The surface topology and overall hydrophobicity of the groove between the core and NC-globules (N-groove) is important for toxin activity and plays a role in selectivity to insect Na(v)s. The N-groove is flanked by Glu24 and Tyr28, which belong to the "pharmacophore" of scorpion beta-toxins, and by the side-chains of Trp53 and Asn58 that are important for receptor site recognition. Substitution of Ala13 by Trp in the N-groove uncoupled activity from binding, suggesting that this region of the molecule is also involved in "voltage-sensor trapping", the mode of action that typifies scorpion beta-toxins. The involvement of the N-groove in recognition of the receptor site, which seems to require a defined topology, as well as in sensor trapping, which involves interaction with a moving channel region, is puzzling. On the basis of the mutagenesis studies we hypothesize that following binding to the receptor site, the toxin undergoes a conformational change at the N-groove region that facilitates the trapping of the voltage-sensor in its activated position.
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Affiliation(s)
- Izhar Karbat
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, and The Daniella Rich Institute for Structural Biology, Tel-Aviv University, Tel-Aviv 69978, Israel
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Bosmans F, Martin-Eauclaire MF, Tytgat J. Differential effects of five 'classical' scorpion beta-toxins on rNav1.2a and DmNav1 provide clues on species-selectivity. Toxicol Appl Pharmacol 2006; 218:45-51. [PMID: 17118417 PMCID: PMC1868420 DOI: 10.1016/j.taap.2006.10.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 10/05/2006] [Accepted: 10/11/2006] [Indexed: 12/19/2022]
Abstract
In general, scorpion beta-toxins have been well examined. However, few in-depth studies have been devoted to species selectivity and affinity comparisons on the different voltage-activated Na(+) channels since they have become available as cloned channels that can be studied in heterologous expression systems. As a result, their classification is largely historical and dates from early in vivo experiments on mice and cockroach and fly larvae. In this study, we aimed to provide an updated overview of selectivity and affinity of scorpion beta-toxins towards voltage-activated Na(+) channels of vertebrates or invertebrates. As pharmacological tools, we used the classic beta-toxins AaHIT, Css II, Css IV, Css VI and Ts VII and tested them on the neuronal vertebrate voltage-activated Na(+) channel, rNa(v)1.2a. For comparison, its invertebrate counterpart, DmNav1, was also tested. Both these channels were expressed in Xenopus laevis oocytes and the currents measured with the two-electrode voltage-clamp technique. We supplemented this data with several binding displacement studies on rat brain synaptosomes. The results lead us to propose a general classification and a novel nomenclature of scorpion beta-toxins based on pharmacological activity.
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Affiliation(s)
- Frank Bosmans
- Laboratory of Toxicology, University of Leuven, O&N 2, Postbus 922, Herestraat 49, 3000 Leuven, Belgium
- * To whom correspondence should be addressed: J. Tytgat, Laboratory of Toxicology, University of Leuven, O&N 2, Postbus 922, Herestraat 49, 3000 Leuven, Belgium. Fax: +3216323405, Tel.: +3216323403. E-mail: ; http://www.toxicology.be
| | - Marie-France Martin-Eauclaire
- CNRS FRE 2732, Biologie des Interactions Moléculaires et Cellulaires, Faculté de Médecine secteur Nord, Institut Jean Roche, Université de la Méditerranée, Bd Pierre Dramard, 13916, Marseille, Cedex 20, France
| | - Jan Tytgat
- Laboratory of Toxicology, University of Leuven, O&N 2, Postbus 922, Herestraat 49, 3000 Leuven, Belgium
- * To whom correspondence should be addressed: J. Tytgat, Laboratory of Toxicology, University of Leuven, O&N 2, Postbus 922, Herestraat 49, 3000 Leuven, Belgium. Fax: +3216323405, Tel.: +3216323403. E-mail: ; http://www.toxicology.be
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Cohen L, Lipstein N, Gordon D. Allosteric interactions between scorpion toxin receptor sites on voltage‐gated Na channels imply a novel role for weakly active components in arthropod venom. FASEB J 2006; 20:1933-5. [PMID: 16877526 DOI: 10.1096/fj.05-5545fje] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Scorpion beta and alpha-toxins modify the activation and inactivation of voltage-gated sodium channels. Although the two types of toxin bind at two distinct receptor sites on the same sodium channel, they exhibit synergic effects when coinjected into insects. To clarify the basis of this synergism we examined the mutual effects of alpha and beta toxin representatives in radio-ligand binding assays. We found positive allosteric interactions between receptor site-4 of the excitatory Bj-xtrIT and the depressant LqhIT2 beta toxins and receptor site-3 of the alpha toxin LqhalphaIT, on locust neuronal membranes. Unexpectedly, a nontoxic mutant Bj-xtrIT-E15R, which binds with high affinity to receptor site-4, was able to enhance LqhalphaIT binding and toxicity similarly to the unmodified Bj-xtrIT. This result indicates that mere binding of a nontoxic ligand to receptor site-4 ("silent binding") induces a conformational change that does not alter channel gating, but influences toxin binding at receptor site-3 leading to enhanced toxicity. This finding suggests a new functional role for weakly toxic polypeptides in that they enhance the effect of other active neurotoxins in the arthropod venom. Such silent binding may have also valuable implications in attempts to improve drug efficacy by combining potent drugs with nonactive allosteric enhancers.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel
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Cohen L, Gilles N, Karbat I, Ilan N, Gordon D, Gurevitz M. Direct evidence that receptor site-4 of sodium channel gating modifiers is not dipped in the phospholipid bilayer of neuronal membranes. J Biol Chem 2006; 281:20673-20679. [PMID: 16720570 DOI: 10.1074/jbc.m603212200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In a recent note to Nature, R. MacKinnon has raised the possibility that potassium channel gating modifiers are able to partition in the phospholipid bilayer of neuronal membranes and that by increasing their partial concentration adjacent to their receptor, they affect channel function with apparent high affinity (Lee and MacKinnon (2004) Nature 430, 232-235). This suggestion was adopted by Smith et al. (Smith, J. J., Alphy, S., Seibert, A. L., and Blumenthal, K. M. (2005) J. Biol. Chem. 280, 11127-11133), who analyzed the partitioning of sodium channel modifiers in liposomes. They found that certain modifiers were able to partition in these artificial membranes, and on this basis, they have extrapolated that scorpion beta-toxins interact with their channel receptor in a similar mechanism as that proposed by MacKinnon. Since this hypothesis has actually raised a new conception, we examined it in binding assays using a number of pharmacologically distinct scorpion beta-toxins and insect and mammalian neuronal membrane preparations, as well as by analyzing the rate by which the toxin effect on gating of Drosophila DmNa(v)1 and rat brain rNa(v)1.2a develops. We show that in general, scorpion beta-toxins do not partition in neuronal membranes and that in the case in which a depressant beta-toxin partitions in insect neuronal membranes, this partitioning is unrelated to its interaction with the receptor site and the effect on the gating properties of the sodium channel. These results negate the hypothesis that the high affinity of beta-toxins for sodium channels is gained by their ability to partition in the phospholipid bilayer and clearly indicate that the receptor site for scorpion beta-toxins is accessible to the extracellular solvent.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Nicolas Gilles
- Commissariat à l'Energie Atomique, Department d'Ingenierie et d'Etudes des Proteines, C.E. Saclay, F-91191 Gif Sur Yvette Cedex, France
| | - Izhar Karbat
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Nitza Ilan
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
| | - Dalia Gordon
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel.
| | - Michael Gurevitz
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel.
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Bel Haj Rhouma R, Cérutti-Duonor M, Benkhadir K, Goudey-Perrière F, El Ayeb M, Lopez-Ferber M, Karoui H. Insecticidal effects of Buthus occitanus tunetanus BotIT6 toxin expressed in Escherichia coli and baculovirus/insect cells. JOURNAL OF INSECT PHYSIOLOGY 2005; 51:1376-83. [PMID: 16216259 DOI: 10.1016/j.jinsphys.2005.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Revised: 08/24/2005] [Accepted: 08/26/2005] [Indexed: 05/04/2023]
Abstract
BotIT6 is a neurotoxin polypeptide derived from the venom of the scorpion Buthus occitanus tunetanus (Bot). Its mature form is composed of 62 amino acids. BotIT6 has been reported to be the most potent toxin from Bot venom that has a strict selectivity for insects. Such toxin may have potential as a potent animal-harmless tool against insects. Using RT-PCR, we isolated and sequenced a cDNA encoding 62 amino acid residues corresponding to the known amino acid sequence of BotIT6. We have expressed a recombinant active form of BotIT6 in significantly high amounts in Escherichia coli. We have also engineered the cDNA into the Autographa californica Nuclear Polyhedrosis Virus (AcMNPV) genome and expressed the protein under control of the polyhedrin promoter. Supernatants of AcIT6-virus infected Sf9 insect cells exhibit a typical intoxication effect when injected to Spodoptera littoralis larvae. Moreover, injection of the recombinant virus showed enhanced insecticidal potency against S. littoralis larvae compared with wild type AcMNPV.
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Affiliation(s)
- Rahima Bel Haj Rhouma
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, Tunis-Belvedère, Tunisia
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36
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Chen T, Walker B, Zhou M, Shaw C. Molecular cloning of a novel putative potassium channel-blocking neurotoxin from the venom of the North African scorpion, Androctonus amoreuxi. Peptides 2005; 26:731-6. [PMID: 15808902 DOI: 10.1016/j.peptides.2004.12.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2004] [Revised: 12/02/2004] [Accepted: 12/03/2004] [Indexed: 11/24/2022]
Abstract
Scorpion venoms are a particularly rich source of neurotoxic proteins/peptides that interact in a highly specific fashion with discrete subtypes of ion channels in excitable and non-excitable cells. Here we have employed a recently developed technique to effect molecular cloning and structural characterization of a novel putative potassium channel-blocking toxin from the same sample of venom from the North African scorpion, Androctonus amoreuxi. The deduced precursor open-reading frame is composed of 59 amino acid residues that consists of a signal peptide of approximately 22 amino acid residues followed by a mature toxin of 37 amino acid residues. The mature toxin contains two functionally important residues (Lys27 and Tyr36), constituting a functional dyad motif that may be critical for potassium channel-blocking activity that can be affirmed from structural homologs as occurring in the venoms from other species of Androctonus scorpions. Parallel proteomic/transcriptomic studies can thus be performed on the same scorpion venom sample without sacrifice of the donor animal.
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Affiliation(s)
- Tianbao Chen
- School of Pharmacy, Queen's University, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK
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37
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Arnon T, Potikha T, Sher D, Elazar M, Mao W, Tal T, Bosmans F, Tytgat J, Ben-Arie N, Zlotkin E. BjalphaIT: a novel scorpion alpha-toxin selective for insects--unique pharmacological tool. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2005; 35:187-195. [PMID: 15705498 DOI: 10.1016/j.ibmb.2004.11.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 10/21/2004] [Accepted: 11/01/2004] [Indexed: 05/24/2023]
Abstract
Long-chain neurotoxins derived from the venom of the Buthidae scorpions, which affect voltage-gated sodium channels (VGSCs) can be subdivided according to their toxicity to insects into insect-selective excitatory and depressant toxins (beta-toxins) and the alpha-like toxins which affect both mammals and insects. In the present study by the aid of reverse-phase HPLC column chromatography, RT-PCR, cloning and various toxicity assays, a new insect selective toxin designated as BjalphaIT was isolated from the venom of the Judean Black Scorpion (Buthotus judaicus), and its full primary sequence was determined: MNYLVVICFALLLMTVVESGRDAYIADNLNCAYTCGSNSYCNTECTKNGAVSGYCQWLGKYGNACWCINLPDKVPIRIPGACR (leader sequence is underlined). Despite its lack of toxicity to mammals and potent toxicity to insects, BjalphaIT reveals an amino acid sequence and an inferred spatial arrangement that is characteristic of the well-known scorpion alpha-toxins highly toxic to mammals. BjalphaITs sharp distinction between insects and mammals was also revealed by its effect on sodium conductance of two cloned neuronal VGSCs heterloguously expressed in Xenopus laevis oocytes and assayed with the two-electrode voltage-clamp technique. BjalphaIT completely inhibits the inactivation process of the insect para/tipE VGSC at a concentration of 100 nM, in contrast to the rat brain Na(v)1.2/beta1 which is resistant to the toxin. The above categorical distinction between mammal and insect VGSCs exhibited by BjalphaIT enables its employment in the clarification of the molecular basis of the animal group specificity of scorpion venom derived neurotoxic polypeptides and voltage-gated sodium channels.
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Affiliation(s)
- Tal Arnon
- Department of Cell and Animal biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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38
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Bosmans F, Martin-Eauclaire MF, Tytgat J. The depressant scorpion neurotoxin LqqIT2 selectively modulates the insect voltage-gated sodium channel. Toxicon 2005; 45:501-7. [PMID: 15733572 DOI: 10.1016/j.toxicon.2004.12.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 12/09/2004] [Accepted: 12/10/2004] [Indexed: 11/30/2022]
Abstract
LqqIT2 is a depressant neurotoxin present in the venom of the Leiurus quinquestriatus quinquestriatus scorpion, one of the world's most dangerous scorpions endemic to dry habitats in Africa and Asia. In order to determine its efficacy, potency and selectivity, LqqIT2 was subjected for the first time to an electrophysiological and pharmacological comparison between two different cloned sodium channels expressed in Xenopus laevis oocytes. Aside from typical beta-toxin effects, LqqIT2 also affected the inactivation process and ion selectivity of the insect voltage-gated sodium channel. The most interesting feature of LqqIT2 is its total insect-selectivity. At a concentration of 1 microM, the insect-voltage-gated sodium channel, para, was profoundly modulated while its mammalian counterpart, the rat brain Na(v)1.2 channel, was not affected. This trait offers excellent prospects for the development of novel insecticides.
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Affiliation(s)
- Frank Bosmans
- Laboratory of Toxicology, Faculty of Pharmacy, University of Leuven, E. Van Evenstraat 4, B-3000 Leuven, Belgium
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39
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Zhang N, Li M, Chen X, Wang Y, Wu G, Hu G, Wu H. Solution structure of BmKK2, a new potassium channel blocker from the venom of chinese scorpion Buthus martensi Karsch. Proteins 2004; 55:835-45. [PMID: 15146482 DOI: 10.1002/prot.20117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A natural K+ channel blocker, BmKK2 (a member of scorpion toxin subfamily alpha-KTx 14), which is composed of 31 amino acid residues and purified from the venom of the Chinese scorpion Buthus martensi Karsch, was characterized using whole-cell patch-clamp recording in rat hippocampal neurons. The three dimensional structure of BmKK2 was determined with two-dimensional NMR spectroscopy and molecular modelling techniques. In solution this toxin adopted a common alpha/beta-motif, but showed distinct local conformation in the loop between alpha-helix and beta-sheet in comparison with typical short-chain scorpion toxins (e.g., CTX and NTX). Also, the alpha helix is shorter and the beta-sheet element is smaller (each strand consisted only two residues). The unusual structural feature of BmKK2 was attributed to the shorter loop between the alpha-helix and beta-sheet and the presence of two consecutive Pro residues at position 21 and 22 in the loop. Moreover, two models of BmKK2/hKv1.3 channel and BmKK2/rSK2 channel complexes were simulated with docking calculations. The results demonstrated the existence of a alpha-mode binding between the toxin and the channels. The model of BmKK2/rSK2 channel complex exhibited favorable contacts both in electrostatic and hydrophobic, including a network of five hydrogen bonds and bigger interface containing seven pairs of inter-residue interactions. In contrast, the model of BmKK2/hKv1.3 channel complex, containing only three pairs of inter-residue interactions, exhibited poor contacts and smaller interface. The results well explained its lower activity towards Kv channel, and predicted that it may prefer a type of SK channel with a narrower entryway as its specific receptor.
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Affiliation(s)
- Naixia Zhang
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, People's Republic of China
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40
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D'Suze G, Sevcik C, Corona M, Zamudio FZ, Batista CVF, Coronas FI, Possani LD. Ardiscretin a novel arthropod-selective toxin from Tityus discrepans scorpion venom. Toxicon 2004; 43:263-72. [PMID: 15033324 DOI: 10.1016/j.toxicon.2003.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Accepted: 12/09/2003] [Indexed: 11/24/2022]
Abstract
A new arthropod selective toxin was purified from the venom of the Venezuelan scorpion Tityus discrepans, and its amino acid sequence, cDNA clone and biological activity are reported here. The amino acid sequence of this peptide, named ardiscretin (from arthropod toxin of T. discrepans) was completed by Edman degradation and mass spectrometry. It is a single polypeptide composed by 61 amino acids with an amidated cysteine residue at the C-terminal end, closely packed by four disulfide bridges. The atomic mass unit (a.m.u.) experimentally determined was 7103.8 a.m.u. This peptide was shown to be specific for invertebrates (crickets, triatomides, crabs and squids), but non-toxic to mice, at the dose assayed. Ardiscretin inhibits the Na(+)-currents of squid giant axons in an apparent irreversible manner, whose inhibitory effect is reached at 30 microM toxin concentration. Sequence comparison showed that it is phylogenetically closely related to insect-specific scorpion toxins. Ardiscretin produced a small depolarization and induced repetitive firing in squid axons resembling those of DDT [1,1'(p-chlorobenzyl)2-tricloretane] in its ability to slow down action potential, to induce repetitive firing, and in that the concentration required for any effect in squid axon is rather high.
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Affiliation(s)
- G D'Suze
- Laboratory of Cellular Neuropharmacology, Biochemistry and Biophysics Center, Inst. venezolano de Inves. Cient., Apartado 21827, Caracas 1020-A, Venezuela.
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Weisel-Eichler A, Libersat F. Venom effects on monoaminergic systems. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2004; 190:683-90. [PMID: 15160282 DOI: 10.1007/s00359-004-0526-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2003] [Revised: 03/16/2004] [Accepted: 04/07/2004] [Indexed: 01/22/2023]
Abstract
The monoamines, dopamine, epinephrine, histamine, norepinephrine, octopamine, serotonin and tyramine serve many functions in animals. Many different venoms have evolved to manipulate monoaminergic systems via a variety of cellular mechanisms, for both offensive and defensive purposes. One common function of monoamines present in venoms is to produce pain. Some monoamines in venoms cause immobilizing hyperexcitation which precedes venom-induced paralysis or hypokinesia. A common function of venom components that affect monoaminergic systems is to facilitate distribution of other venom components by causing vasodilation at the site of injection or by increasing heart rate. Venoms of some scorpions, spiders, fish and jellyfish contain adrenergic agonists or cause massive release of catecholamines with serious effects on the cardiovascular system, including increased heart rate. Other venom components act as agonists, antagonists or modulators at monoaminergic receptors, or affect release, reuptake or synthesis of monoamines. Most arthropod venoms have insect targets, yet, little attention has been paid to possible effects of these venoms on monoaminergic systems in insects. Further research into this area may reveal novel effects of venom components on monoaminergic systems at the cellular, systems and behavioral levels.
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Affiliation(s)
- Aviva Weisel-Eichler
- Department of Life Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, P.O. Box 653, 84105, Beer Sheva, Israel.
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42
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Cohen L, Karbat I, Gilles N, Froy O, Corzo G, Angelovici R, Gordon D, Gurevitz M. Dissection of the Functional Surface of an Anti-insect Excitatory Toxin Illuminates a Putative “Hot Spot” Common to All Scorpion β-Toxins Affecting Na+ Channels. J Biol Chem 2004; 279:8206-11. [PMID: 14672947 DOI: 10.1074/jbc.m307531200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scorpion beta-toxins affect the activation of voltage-sensitive sodium channels (NaChs). Although these toxins have been instrumental in the study of channel gating and architecture, little is known about their active sites. By using an efficient system for the production of recombinant toxins, we analyzed by point mutagenesis the entire surface of the beta-toxin, Bj-xtrIT, an anti-insect selective excitatory toxin from the scorpion Buthotus judaicus. Each toxin mutant was purified and analyzed using toxicity and binding assays, as well as by circular dichroism spectroscopy to discern the differences among mutations that caused structural changes and those that specifically affected bioactivity. This analysis highlighted a functional discontinuous surface of 1405 A(2), which was composed of a number of non-polar and three charged amino acids clustered around the main alpha-helical motif and the C-tail. Among the charged residues, Glu(30) is a center of a putative "hot spot" in the toxin-receptor binding-interface and is shielded from bulk solvent by a hydrophobic "gasket" (Tyr(26) and Val(34)). Comparison of the Bj-xtrIT structure with that of other beta-toxins that are active on mammals suggests that the hot spot and an adjacent non-polar region are spatially conserved. These results highlight for the first time structural elements that constitute a putative "pharmacophore" involved in the interaction of beta-toxins with receptor site-4 on NaChs. Furthermore, the unique structure of the C-terminal region most likely determines the specificity of excitatory toxins for insect NaChs.
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Affiliation(s)
- Lior Cohen
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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43
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Chen T, Folan R, Kwok H, O'Kane EJ, Bjourson AJ, Shaw C. Isolation of scorpion (Androctonus amoreuxi) putative alpha neurotoxins and parallel cloning of their respective cDNAs from a single sample of venom. REGULATORY PEPTIDES 2003; 115:115-21. [PMID: 12972326 DOI: 10.1016/s0167-0115(03)00146-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The venoms of buthid scorpions are known to contain basic, single-chain protein toxins (alpha toxins) consisting of 60-70 amino acid residues that are tightly folded by four disulfide bridges. Here we describe isolation and sequencing of three novel putative alpha toxins (AamH1-3) from the venom of the North African scorpion, Androctonus amoreuxi, and subsequent cloning of their precursor cDNAs from the same sample of venom. This experimental approach can expedite functional genomic analyses of the protein toxins from this group of venomous animals and does not require specimen sacrifice for cloning of protein toxin precursor cDNAs.
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Affiliation(s)
- Tianbao Chen
- Pharmaceutical Biotechnology Research Group, School of Biomedical Sciences, University of Ulster, Cromore Road, BT52 1SA, Northern Ireland, Coleraine, UK
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44
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Mejri T, Borchani L, Srairi-Abid N, Benkhalifa R, Cestele S, Regaya I, Karoui H, Pelhate M, Rochat H, El Ayeb M. BotIT6: a potent depressant insect toxin from Buthus occitanus tunetanus venom. Toxicon 2003; 41:163-71. [PMID: 12565735 DOI: 10.1016/s0041-0101(02)00246-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A new depressant insect toxin Buthus occitanus tunetanus insect-toxin 6 (BotIT6) was purified by high-performance liquid chromatography from Buthus occitanus tunetanus (Bot) venom. BotIT6 is very active against Blatella germanica (LD50=10ng/100mg body mass) thus being one of the most potent anti-insect toxin so far characterised. When compared to other insect toxin sequences, BotIT6 present high similarities with depressant insect toxins with an additional arginine residue at the C-terminus and a methionine at position 27. The calculated net charge of BotIT6 is positive (+3) whereas it is negative for classical depressant toxins: this might be associated with its high toxicity. Voltage current clump studies show that BotIT6 is not a very potent depressant insect toxin despite its high toxicity in vivo. BotIT6 is able to fully inhibit the specific binding of 125I AaHIT and 125I-BotIT2 on Periplaneta americana synaptosomal membrane vesicles with high affinities. Despite its higher toxicity BotIT6 is a weaker competitor with 125I AaHIT and 125I BotIT2 as compared to the other beta toxins.Altogether, these results may suggest that BotIT6 probably defines a novel sub-group of depressant anti-insect toxins for which the receptor site can be overlapping, but not identical to that for classical depressant insect toxins.
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Affiliation(s)
- Thouraya Mejri
- Laboratoire des Venins et Toxines, Institut Pasteur de Tunis, BP 74-1002, Tunis, Tunisia.
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45
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Wudayagiri R, Inceoglu B, Herrmann R, Derbel M, Choudary PV, Hammock BD. Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus. BMC BIOCHEMISTRY 2003; 2:16. [PMID: 11782289 PMCID: PMC64496 DOI: 10.1186/1471-2091-2-16] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2001] [Accepted: 12/17/2001] [Indexed: 11/10/2022]
Abstract
BACKGROUND Scorpion venom contains insect and mammal selective toxins. We investigated the venom of the South Indian red scorpion, Mesobuthus tamulus for the purpose of identifying potent insecticidal peptide toxins. RESULTS A lepidopteran-selective toxin (Buthus tamulus insect toxin; ButaIT) has been isolated from this venom. The primary structure analysis reveals that it is a single polypeptide composed of 37 amino acids cross-linked by four disulfide bridges with high sequence homology to other short toxins such as Peptide I, neurotoxin P2, Lqh-8/6, chlorotoxin, insectotoxin I5A, insect toxin 15 and insectotoxin I1. Three dimensional modeling using Swiss automated protein modeling server reveals that this toxin contains a short alpha-helix and three antiparallel beta-strands, similar to other short scorpion toxins. This toxin is selectively active on Heliothis virescens causing flaccid paralysis but was non-toxic to blowfly larvae and mice. CONCLUSION This is the first report of a Heliothine selective peptide toxin. Identification of diverse insect selective toxins offer advantages in employing these peptides selectively for pest control.
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Affiliation(s)
- Rajendra Wudayagiri
- Department of Zoology, Sri Venkateswara University, Tirupati – 517 502, India
- Department of Entomology, University of California, Davis, CA 95616, USA
| | - Bora Inceoglu
- Department of Entomology, University of California, Davis, CA 95616, USA
| | - Rafael Herrmann
- DuPont Agricultural Products, Stine-Haskel Research Center, P.O. Box 30, Elkton Road, Newark, DE 19714, USA
| | - Maher Derbel
- Department of Entomology, University of California, Davis, CA 95616, USA
| | | | - Bruce D Hammock
- Department of Entomology, University of California, Davis, CA 95616, USA
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46
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Wang CG, Ling MH, Chi CW, Wang DC, Pelhate M. Purification of two depressant insect neurotoxins and their gene cloning from the scorpion Buthus martensi Karsch. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 61:7-16. [PMID: 12472844 DOI: 10.1034/j.1399-3011.2003.21020.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Insect-specific neurotoxins are important components of scorpion venoms. In this study, two toxins from the scorpion Buthus martensi Karsch (BmK) were purified. They shared high sequence homology with other depressant insect toxins and were designated BmK ITa and BmK ITb, respectively. They were able to suppress the action potential of cockroach isolated axon, which is due to a decrease in the peak sodium current. Furthermore, the effect of BmK ITb was lower than that of BmK ITa, and some of the electrophysiological characteristics of BmK ITb even resemble that of excitatory insect toxins. Their primary structures were determined by N-terminal partial sequence determination and cDNA cloning. The differences in their structures, especially the 31st residues, may result in the unique activity of BmK ITb.
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Affiliation(s)
- C-G Wang
- Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China
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47
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Zaki TI, Maruniak JE. Three polymorphic genes encoding a depressant toxin from the Egyptian scorpion Leiurus quinquestriatus quinquestriatus. Toxicon 2003; 41:109-13. [PMID: 12467668 DOI: 10.1016/s0041-0101(02)00242-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Four clones encoding the insect depressant toxin LqqIT2 have been isolated from the Egyptian scorpion Leiurus quinquestriatus quinquestriatus using RT-PCR. The four clones have been sequenced and their deduced amino acid sequences have been compared with the original amino acid sequence determined from the purified LqqIT2 protein and polymorphisms have been shown. This study succeeded in isolating more than one copy of the LqqIT2 gene, although only one amino acid sequence has been identified from the purified LqqIT2 toxin.
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Affiliation(s)
- Tamer I Zaki
- Department of Microbiology and Cell Science, University of Florida, P.O. Box 110620, Gainesville, FL 32611, USA.
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48
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Goudet C, Chi CW, Tytgat J. An overview of toxins and genes from the venom of the Asian scorpion Buthus martensi Karsch. Toxicon 2002; 40:1239-58. [PMID: 12220709 DOI: 10.1016/s0041-0101(02)00142-3] [Citation(s) in RCA: 205] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Among the different scorpion species, Buthus martensi Karsch (BmK), a widely distributed scorpion species in Asia, has received a lot of attention. Indeed, over the past decade, more than 70 different peptides, toxins or homologues have been isolated and more peptides are probably still to be revealed. This review is focusing on the many peptides isolated from the venom of this scorpion, their targets, their genes and their structures. The aim is to give both a 'state of the art' view of the research on BmK venom and an illustration of the complexity of this scorpion venom. In the present manuscript, we have listed the different ion channel toxins and homologues isolated from the venom of BmK, either from the literature or from databases. We have described here 51 long-chain peptides related to the Na(+) channel toxins family: 34 related to the alpha-toxin family, four related to the excitatory insect toxin family, 10 related to the depressant insect toxin, one beta-like toxin plus two peptides, BmK AS and AS1, that act on ryanodine receptors. We also listed 18 peptides related to the K(+) channel toxin family: 14 short chain toxins or homologues, two long chain K(+) toxin homologues and two putative K(+) toxin precursors. Additionally, two chlorotoxin like peptides (Bm-12 and 12 b) have been isolated in the venom of BmK. Besides these ion channels toxins, two peptides without disulfide bridges (the bradykinin-potentiating peptide BmK bpp and BmK n1) and three peptides with no known functions have also been discovered in this venom. We have also taken the opportunity of this review to update the classification of scorpion K(+) toxins () which now presents 17 subfamilies instead of the 12 described earlier. The work on the venom of BmK led to the discovery of two new subfamilies, alpha-KT x 14 and alpha-KT x 17.
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Affiliation(s)
- Cyril Goudet
- Laboratory of Toxicology, Faculty of Pharmaceutical Sciences, University of Leuven, Van Evenstraat 4, B-3000, Leuven, Belgium
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Ji SJ, Liu F, Li EQ, Zhu YX. Recombinant scorpion insectotoxin AaIT kills specifically insect cells but not human cells. Cell Res 2002; 12:143-50. [PMID: 12118940 DOI: 10.1038/sj.cr.7290120] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The nucleotide sequence deduced from the amino acid sequence of the scorpion insectotoxin AaIT was chemically synthesized and was expressed in Escherichia coli. The authenticity of this in vitro expressed peptide was confirmed by N-terminal peptide sequencing. Two groups of bioassays, artificial diet incorporation assay and contact insecticidal effect assay, were carried out separately to verify the toxicity of this recombinant toxin. At the end of a 24 h experimental period, more than 60% of the testing diamondback moth (Plutella xylostella) larvae were killed in both groups with LC50 value of 18.4 microM and 0.70 microM respectively. Cytotoxicity assay using cultured Sf9 insect cells and MCF-7 human cells demonstrated that the toxin AaIT had specific toxicity against insect cells but not human cells. Only 0.13 microM recombinant toxin was needed to kill 50% of cultured insect cells while as much as 1.3 microM toxin had absolutely no effect on human cells. Insect cells produced obvious intrusions from their plasma membrane before broken up. We infer that toxin AaIT bind to a putative sodium channel in these insect cells and open the channel persistently, which would result in Na+ influx and finally cause destruction of insect cells.
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Affiliation(s)
- Sheng Jian Ji
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing, China
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Guan R, Wang CG, Wang M, Wang DC. A depressant insect toxin with a novel analgesic effect from scorpion Buthus martensii Karsch. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1549:9-18. [PMID: 11566364 DOI: 10.1016/s0167-4838(01)00241-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A new peptide named BmK dITAP3 from scorpion Buthus martensii Karsch (BmK) has been identified to possess a dual bioactivity, a depressant neurotoxicity on insects and an analgesic effect on mice. The bioassays also showed that the peptide was definitely devoid of the neurotoxicity on mammals, which indicated that the analgesic effect of BmK dITAP3 could not be ascribed to the syndromic effects of a mammalian neurotoxicity. BmK dITAP3 exhibited 43.0% inhibition efficiency of the analgesic effect on mice at a dose of 5 mg/kg and the FPU value of 0.5 microg/body (approximately 30 mg) on the fly larvae. The pI value and the molecular mass determined by MALDI-TOF MS for dITAP3 were 6.5 and 6722.7, respectively. Its first 15 N-terminal residues were determined by Edman degradation, based on which the full amino acid sequence was deduced from the cDNA sequence encoding the peptide with 3'-RACE. Circular dichroism and sequence based prediction analyses showed dITAP3 may have a similar molecular scaffold as the most scorpion toxins but with features of the more beta structures and much less of alpha helix. The details of the purification, characterization and sequencing as well as the sequence comparison with other depressant insect toxins and the correlation between the analgesic effect and the insect toxicity will be reported and discussed, respectively.
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Affiliation(s)
- R Guan
- Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China
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