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Kalita B, Utkin YN, Mukherjee AK. Current Insights in the Mechanisms of Cobra Venom Cytotoxins and Their Complexes in Inducing Toxicity: Implications in Antivenom Therapy. Toxins (Basel) 2022; 14:toxins14120839. [PMID: 36548736 PMCID: PMC9780984 DOI: 10.3390/toxins14120839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 12/02/2022] Open
Abstract
Cytotoxins (CTXs), an essential class of the non-enzymatic three-finger toxin family, are ubiquitously present in cobra venoms. These low-molecular-mass toxins, contributing to about 40 to 60% of the cobra venom proteome, play a significant role in cobra venom-induced toxicity, more prominently in dermonecrosis. Structurally, CTXs contain the conserved three-finger hydrophobic loops; however, they also exhibit a certain degree of structural diversity that dictates their biological activities. In their mechanism, CTXs mediate toxicity by affecting cell membrane structures and membrane-bound proteins and activating apoptotic and necrotic cell death pathways. Notably, some CTXs are also responsible for depolarizing neurons and heart muscle membranes, thereby contributing to the cardiac failure frequently observed in cobra-envenomed victims. Consequently, they are also known as cardiotoxins (CdTx). Studies have shown that cobra venom CTXs form cognate complexes with other components that potentiate the toxic effects of the venom's individual component. This review focuses on the pharmacological mechanism of cobra venom CTXs and their complexes, highlighting their significance in cobra venom-induced pathophysiology and toxicity. Furthermore, the potency of commercial antivenoms in reversing the adverse effects of cobra venom CTXs and their complexes in envenomed victims has also been discussed.
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Affiliation(s)
- Bhargab Kalita
- Amrita School of Nanosciences and Molecular Medicine, Amrita Vishwa Vidyapeetham, Kochi 682041, India
| | - Yuri N. Utkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Ashis K. Mukherjee
- Institute of Advanced Study in Science and Technology, Guwahati 781035, India
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur 784028, India
- Correspondence:
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Hiu JJ, Yap MKK. The myth of cobra venom cytotoxin: More than just direct cytolytic actions. Toxicon X 2022; 14:100123. [PMID: 35434602 PMCID: PMC9011113 DOI: 10.1016/j.toxcx.2022.100123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 03/03/2022] [Accepted: 03/31/2022] [Indexed: 12/26/2022] Open
Abstract
Cobra venom cytotoxin (CTX) is a non-enzymatic three-finger toxin that constitutes 40-60% of cobra venom. Thus, it plays an important role in the pathophysiology of cobra envenomation, especially in local dermonecrosis. The three-finger hydrophobic loops of CTX determine the cytotoxicity. Nevertheless, the actual mechanisms of cytotoxicity are not fully elucidated as they involve not only cytolytic actions but also intracellular signalling-mediated cell death pathways. Furthermore, the possible transition cell death pattern remains to be explored. The actual molecular mechanisms require further studies to unveil the relationship between different CTXs from different cobra species and cell types which may result in differential cell death patterns. Here, we discuss the biophysical interaction of CTX with the cell membrane involving four binding modes: electrostatic interaction, hydrophobic partitioning, isotropic phase, and oligomerisation. Oligomerisation of CTX causes pore formation in the membrane lipid bilayer. Additionally, the CTX-induced apoptotic pathway can be executed via death receptor-mediated extrinsic pathways and mitochondrial-mediated intrinsic pathways. We also discuss lysosomal-mediated necrosis and the occurrence of necroptosis following CTX action. Collectively, we provided an insight into concentration-dependent transition of cell death pattern which involves different mechanistic actions. This contributes a new direction for further investigation of cytotoxic pathways activated by the CTXs for future development of biotherapeutics targeting pathological effects caused by CTX.
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Affiliation(s)
- Jia Jin Hiu
- School of Science, Monash University Malaysia, Bandar Sunway, Malaysia
| | - Michelle Khai Khun Yap
- School of Science, Monash University Malaysia, Bandar Sunway, Malaysia.,Tropical Medicine and Biology Multidisciplinary Platform, Monash University Malaysia, Bandar Sunway, Malaysia
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Wu GL, Shi YJ, Chiou JT, Huang CH, Lee YC, Wang LJ, Chang LS. Functional and structural properties of cardiotoxin isomers produced by blocking negatively charged groups. Arch Biochem Biophys 2022; 722:109209. [DOI: 10.1016/j.abb.2022.109209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2022] [Revised: 03/28/2022] [Accepted: 03/30/2022] [Indexed: 11/30/2022]
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Shi YJ, Chiou JT, Wang LJ, Huang CH, Lee YC, Chen YJ, Chang LS. Blocking of negative charged carboxyl groups converts Naja atra neurotoxin to cardiotoxin-like protein. Int J Biol Macromol 2020; 164:2953-2963. [PMID: 32846183 DOI: 10.1016/j.ijbiomac.2020.08.163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 08/20/2020] [Indexed: 11/28/2022]
Abstract
Naja atra cobrotoxin and cardiotoxin 3 (CTX3) exhibit neurotoxicity and cytotoxicity, respectively. In the present study, we aimed to investigate whether the carboxyl groups of cobrotoxin play a role in structural constraints, thereby preventing cobrotoxin from exhibiting cytotoxic activity. Six of the seven carboxyl groups in cobrotoxin were conjugated with semicarbazide. Measurement of circular dichroism spectra and Trp fluorescence quenching showed that the gross conformation of semicarbazide-modified cobrotoxin (SEM-cobrotoxin) and cobrotoxin differed. In sharp contrast to cobrotoxin, SEM-cobrotoxin demonstrated membrane-damaging activity and cytotoxicity, which are feature more characteristic of CTX3. Furthermore, both SEM-cobrotoxin and CTX3 induced cell death through AMPK activation. Analyses of the interaction between polydiacetylene/lipid vesicles and fluorescence-labeled lipids revealed that SEM-cobrotoxin and cobrotoxin adopted different membrane-bound states. The structural characteristics of SEM-cobrotoxin were similar to those of CTX3, including trifluoroethanol (TFE)-induced structural transformation and membrane binding-induced conformational change. Conversely, cobrotoxin was insensitive to the TFE-induced effect. Collectively, the data of this study indicate that blocking negatively charged residues confers cobrotoxin with membrane-damaging activity and cytotoxicity. The findings also suggest that the structural constraints imposed by carboxyl groups control the functional properties of snake venom α-neurotoxins during the divergent evolution of snake venom neurotoxins and cardiotoxins.
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Affiliation(s)
- Yi-Jun Shi
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Jing-Ting Chiou
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Liang-Jun Wang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Chia-Hui Huang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Yuan-Chin Lee
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan
| | - Ying-Jung Chen
- Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan
| | - Long-Sen Chang
- Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung 804, Taiwan; Department of Biotechnology, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
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Status of Asp29 and Asp40 in the Interaction of Naja atra Cardiotoxins with Lipid Bilayers. Toxins (Basel) 2020; 12:toxins12040262. [PMID: 32325789 PMCID: PMC7232319 DOI: 10.3390/toxins12040262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 01/10/2023] Open
Abstract
It is widely accepted that snake venom cardiotoxins (CTXs) target the plasma membranes of cells. In the present study, we investigated the role of Asp residues in the interaction of Naja atra cardiotoxin 1 (CTX1) and cardiotoxin 3 (CTX3) with phospholipid bilayers using chemical modification. CTX1 contains three Asp residues at positions 29, 40, and 57; CTX3 contains two Asp residues at positions 40 and 57. Compared to Asp29 and Asp40, Asp57 was sparingly modified with semi-carbazide, as revealed by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass and mass/mass analyses. Thus, semi-carbazide-modified CTX1 (SEM-CTX1) mainly contained modified Asp29 and Asp40, while SEM-CTX3 contained modified Asp40. Compared to that of native toxins, trifluoroethanol easily induced structural transition of SEM-CTX1 and SEM-CTX3, suggesting that the structural flexibility of CTXs was constrained by Asp40. Modification of Asp29 and Asp40 markedly promoted the ability of CTX1 to induce permeability of cell membranes and lipid vesicles; CTX3 and SEM-CTX3 showed similar membrane-damaging activity. Modification of Asp residues did not affect the membrane-binding capability of CTXs. Circular dichroism spectra of SEM-CTX3 and CTX3 were similar, while the gross conformation of SEM-CTX1 was distinct from that of CTX1. The interaction of CTX1 with membrane was distinctly changed by Asp modification. Collectively, our data suggest that Asp29 of CTX1 suppresses the optimization of membrane-bound conformation to a fully active state and that the function of Asp40 in the structural constraints of CTX1 and CTX3 is not important for the manifestation of membrane-perturbing activity.
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Antibacterial activity of cardiotoxin-like basic polypeptide from cobra venom. Bioorg Med Chem Lett 2020; 30:126890. [DOI: 10.1016/j.bmcl.2019.126890] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 02/06/2023]
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Forouhar F, Huang WN, Liu JH, Chien KY, Wu WG, Hsiao CD. Structural basis of membrane-induced cardiotoxin A3 oligomerization. J Biol Chem 2003; 278:21980-8. [PMID: 12660250 DOI: 10.1074/jbc.m208650200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cobra cardiotoxins (CTXs) have previously been shown to induce membrane fusion of vesicles formed by phospholipids such as cardiolipin or sphingomyelin. CTX can also form a pore in membrane bilayers containing a anionic lipid such as phosphatidylserine or phosphatidylglycerol. Herein, we show that the interaction of CTX with negatively charged lipids causes CTX dimerization, an important intermediate for the eventual oligomerization of CTX during the CTX-induced fusion and pore formation process. The structural basis of the lipid-induced oligomerization of CTX A3, a major CTX from Naja atra, is then illustrated by the crystal structure of CTX A3 in complex with SDS; SDS likely mimics anionic lipids of the membrane under micelle conditions at 1.9-A resolution. The crystal packing reveals distinct SDS-free and SDS-rich regions; in the latter two types of interconnecting CTX A3 dimers, D1 and D2, and several SDS molecules can be identified to stabilize D1 and D2 by simultaneously interacting with residues at each dimer interface. When the three CTXSDS complexes in the asymmetric unit are overlaid, the orientation of CTX A3 monomers relative to the SDS molecules in the crystal is strikingly similar to that of the toxin with respect to model membranes as determined by NMR and Fourier transform infrared methods. These results not only illustrate how lipid-induced CTX dimer formation may be transformed into oligomers either as inverted micelles of fusion intermediates or as membrane pore of anionic lipid bilayers but also underscore a potential role for SDS in x-ray diffraction study of protein-membrane interactions in the future.
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Affiliation(s)
- Farhad Forouhar
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 115
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Zhang Y, Tu AT. The effect of snake venoms and their components on adrenomedullary cells: catecholamine efflux and cell damage. Neurotoxicology 2002; 23:273-9. [PMID: 12387355 DOI: 10.1016/s0161-813x(02)00019-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The effects of snake venom on the cholinergic system have been well-studied; however, no similar studies have been performed on the adrenergic system. Adrenomedullary cells secrete catecholamine (CA) on stimulation; thus they are an ideal system to study the effect of snake venoms on CA secretion or inhibition. Snake venoms from different Families and Genera were investigated. All snake venoms investigated, caused CA efflux. CA can be released when cytolysis takes place; so in order to assert CA efflux was not due to cytolysis, venoms were added after the cells were treated with KCl. Most venom, with the exception of sea snake (Hydrophiidae) venom, was found to induce CA release due to cytolysis. The effects of purified components such as phospholipase A2, neurotoxin I, and cardiotoxin were also investigated. Neurotoxin I caused neither cytolysis nor CA efflux. Cardiotoxin caused marked cytolysis, but with slightly less damaging effects than that of cobra venom. Some ion channel blockers prevented cytolysis induced by cardiotoxin. The CA efflux induced by cardiotoxin may be mediated through Ca2+ channels because the efflux could be completely depressed by a Ca2+ channel blocker (1 mM CdCl2).
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Affiliation(s)
- Yuang Zhang
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins 80523, USA
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Brinda KV, Kannan N, Vishveshwara S. Analysis of homodimeric protein interfaces by graph-spectral methods. Protein Eng Des Sel 2002; 15:265-77. [PMID: 11983927 DOI: 10.1093/protein/15.4.265] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The quaternary structures impart structural and functional credibility to proteins. In a multi-subunit protein, it is important to understand the factors that drive the association or dissociation of the subunits. It is a well known fact that both hydrophobic and charged interactions contribute to the stability of the protein interface. The interface residues are also known to be highly conserved. Though they are buried in the oligomer, these residues are either exposed or partially exposed in the monomer. It is felt that a systematic and objective method of identifying interface clusters and their analysis can significantly contribute to the identification of a residue or a collection of residues important for oligomerization. Recently, we have applied the techniques of graph-spectral methods to a variety of problems related to protein structure and folding. A major advantage of this methodology is that the problem is viewed from a global protein topology point of view rather than localized regions of the protein structure. In the present investigation, we have applied the methods of graph-spectral analysis to identify side chain clusters at the interface and the centers of these clusters in a set of homodimeric proteins. These clusters are analyzed in terms of properties such as amino acid composition, accessibility to solvent and conservation of residues. Interesting results such as participation of charged and aromatic residues like arginine, glutamic acid, histidine, phenylalanine and tyrosine, consistent with earlier investigations, have emerged from these analyses. Important additional information is that the residues involved are a part of a cluster(s) and that they are sequentially distant residues which have come closer to each other in the three-dimensional structure of the protein. These residues can easily be detected using our graph-spectral algorithm. This method has also been used to identify important residues ('hot spots') in dimerization and also to detect dimerization sites on the monomer. The residues predicted using the present algorithm have correlated well with the experiments indicating the efficacy of this method in predicting residues involved in dimer stability.
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Affiliation(s)
- K V Brinda
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
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