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Schreuder M, Liu X, Cheung KL, Reitsma PH, Nicolaes GAF, Bos MHA. ptFVa ( Pseudonaja Textilis Venom-Derived Factor Va) Retains Structural Integrity Following Proteolysis by Activated Protein C. Arterioscler Thromb Vasc Biol 2021; 41:2263-2276. [PMID: 34162230 PMCID: PMC8288481 DOI: 10.1161/atvbaha.121.316038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Objective: The Australian snake venom ptFV (Pseudonaja textilis venom-derived factor V) variant retains cofactor function despite APC (activated protein C)-dependent proteolysis. Here, we aimed to unravel the mechanistic principles by determining the role of the absent Arg306 cleavage site that is required for the inactivation of FVa (mammalian factor Va). Approach and Results: Our findings show that in contrast to human FVa, APC-catalyzed proteolysis of ptFVa at Arg306 and Lys507 does not abrogate ptFVa cofactor function. Remarkably, the structural integrity of APC-proteolyzed ptFVa is maintained indicating that stable noncovalent interactions prevent A2-domain dissociation. Using Molecular Dynamics simulations, we uncovered key regions located in the A1 and A2 domain that may be at the basis of this remarkable characteristic. Conclusions: Taken together, we report a completely novel role for uniquely adapted regions in ptFVa that prevent A2 domain dissociation. As such, these results challenge our current understanding by which strict regulatory mechanisms control FVa activity.
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Affiliation(s)
- Mark Schreuder
- Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, the Netherlands (M.S., K.L.C., P.H.R., M.H.A.B.)
| | - Xiaosong Liu
- Maastricht University, Department of Biochemistry, the Netherlands (X.L.)
| | - Ka Lei Cheung
- Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, the Netherlands (M.S., K.L.C., P.H.R., M.H.A.B.)
| | - Pieter H Reitsma
- Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, the Netherlands (M.S., K.L.C., P.H.R., M.H.A.B.).,VarmX B.V, Leiden, the Netherlands (P.H.R.)
| | | | - Mettine H A Bos
- Division of Thrombosis and Hemostasis, Einthoven Laboratory for Vascular and Regenerative Medicine, Leiden University Medical Center, the Netherlands (M.S., K.L.C., P.H.R., M.H.A.B.)
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Kini RM. Toxinology provides multidirectional and multidimensional opportunities: A personal perspective. Toxicon X 2020; 6:100039. [PMID: 32550594 PMCID: PMC7285919 DOI: 10.1016/j.toxcx.2020.100039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 04/28/2020] [Accepted: 05/05/2020] [Indexed: 01/16/2023] Open
Abstract
In nature, toxins have evolved as weapons to capture and subdue the prey or to counter predators or competitors. When they are inadvertently injected into humans, they cause symptoms ranging from mild discomfort to debilitation and death. Toxinology is the science of studying venoms and toxins that are produced by a wide variety of organisms. In the past, the structure, function and mechanisms of most abundant and/or most toxic components were characterized to understand and to develop strategies to neutralize their toxicity. With recent technical advances, we are able to evaluate and determine the toxin profiles using transcriptomes of venom glands and proteomes of tiny amounts of venom. Enormous amounts of data from these studies have opened tremendous opportunities in many directions of basic and applied research. The lower costs for profiling venoms will further fuel the expansion of toxin database, which in turn will provide greater exciting and bright opportunities in toxin research.
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Affiliation(s)
- R. Manjunatha Kini
- Protein Science Laboratory, Department of Biological Sciences, Faculty of Science and Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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3
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Han SX, Kwong S, Ge R, Kolatkar PR, Woods AE, Blanchet G, Kini RM. Regulation of expression of venom toxins: silencing of prothrombin activator trocarin D by AG‐rich motifs. FASEB J 2016; 30:2411-25. [DOI: 10.1096/fj.201600213r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/29/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Summer Xia Han
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Shiyang Kwong
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Ruowen Ge
- Department of Biological SciencesNational University of SingaporeSingapore
| | - Prasanna R. Kolatkar
- Qatar Biomedical Research Institute, Hamad Bin Khalifa University, Qatar Foundation for Education, Science, and Community DevelopmentDohaQatar
| | - Anthony E. Woods
- School of Pharmacy and Medical SciencesUniversity of South AustraliaAdelaideSouth AustraliaAustralia
| | - Guillaume Blanchet
- Department of Biological SciencesNational University of SingaporeSingapore
| | - R. Manjunatha Kini
- Department of Biological SciencesNational University of SingaporeSingapore
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4
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Venomics of the Australian eastern brown snake ( Pseudonaja textilis ): Detection of new venom proteins and splicing variants. Toxicon 2015; 107:252-65. [DOI: 10.1016/j.toxicon.2015.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 06/08/2015] [Accepted: 06/11/2015] [Indexed: 01/28/2023]
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Deep venomics of the Pseudonaja genus reveals inter- and intra-specific variation. J Proteomics 2015; 133:20-32. [PMID: 26632978 DOI: 10.1016/j.jprot.2015.11.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 11/14/2015] [Accepted: 11/24/2015] [Indexed: 01/21/2023]
Abstract
UNLABELLED Australian elapid venom remains an under-investigated resource of novel bioactive peptides. In this study, the venom gland transcriptomes and proteomes of the Australian western brown snakes, Pseudonaja aspidorhyncha and Pseudonaja nuchalis, were compared to Pseudonaja textilis. A deep venomics strategy incorporating high throughput 454 pyrosequencing gave a total of 200,911 raw reads for the three venoms. Subsequent annotation identified 5716 transcripts from 20 different toxin families with inter-specific variation between species observed in eight of the less abundant families. Integration of each venom proteome with the corresponding annotated reads identified 65 isoforms from six toxin families; high sequence coverage highlighted subtle differences between sequences and intra and inter-specific variation between species. High quality MS/MS data identified unusual glycoforms with natriuretic peptides from P. aspidorhyncha and P. nuchaliscontaining O-linked trisaccharides with high homology to the glycosylated region of TNPc. Molecular evolutionary assessments indicated the accelerated evolution of all toxin families with the exception of both natriuretic peptides and P. aspidorhyncha PLA2s that were found to be evolutionarily constrained under purifying selection pressures. This study has revealed a wide range of novel peptide sequences from six bioactive peptide families and highlights the subtle differences between toxins in these closely related species. BIOLOGICAL SIGNIFICANCE Mining Australia's vastly untapped source of toxins from its venomous creatures has been significantly advanced by employing deep venomics methodology. Technological advances in transcriptome analysis using next generation sequencing platforms and proteome analysis by highly sensitive tandem mass spectrometry allowed a more comprehensive interrogation of three underinvestigated brown snake (Pseudonaja) venoms uncovering many novel peptide sequences that are unique to these closely related species. This generic strategy will provide invaluable information when applied to other venomous snakes for a deeper understanding of venom composition, envenomation, venom evolution, as well as identifying research tools and drug leads.
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Gacesa R, Chung R, Dunn SR, Weston AJ, Jaimes-Becerra A, Marques AC, Morandini AC, Hranueli D, Starcevic A, Ward M, Long PF. Gene duplications are extensive and contribute significantly to the toxic proteome of nematocysts isolated from Acropora digitifera (Cnidaria: Anthozoa: Scleractinia). BMC Genomics 2015; 16:774. [PMID: 26464356 PMCID: PMC4604070 DOI: 10.1186/s12864-015-1976-4] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/03/2015] [Indexed: 11/10/2022] Open
Abstract
Background Gene duplication followed by adaptive selection is a well-accepted process leading to toxin diversification in venoms. However, emergent genomic, transcriptomic and proteomic evidence now challenges this role to be at best equivocal to other processess . Cnidaria are arguably the most ancient phylum of the extant metazoa that are venomous and such provide a definitive ancestral anchor to examine the evolution of this trait. Methods Here we compare predicted toxins from the translated genome of the coral Acropora digitifera to putative toxins revealed by proteomic analysis of soluble proteins discharged from nematocysts, to determine the extent to which gene duplications contribute to venom innovation in this reef-building coral species. A new bioinformatics tool called HHCompare was developed to detect potential gene duplications in the genomic data, which is made freely available (https://github.com/rgacesa/HHCompare). Results A total of 55 potential toxin encoding genes could be predicted from the A. digitifera genome, of which 36 (65 %) had likely arisen by gene duplication as evinced using the HHCompare tool and verified using two standard phylogeny methods. Surprisingly, only 22 % (12/55) of the potential toxin repertoire could be detected following rigorous proteomic analysis, for which only half (6/12) of the toxin proteome could be accounted for as peptides encoded by the gene duplicates. Biological activities of these toxins are dominatedby putative phospholipases and toxic peptidases. Conclusions Gene expansions in A. digitifera venom are the most extensive yet described in any venomous animal, and gene duplication plays a significant role leading to toxin diversification in this coral species. Since such low numbers of toxins were detected in the proteome, it is unlikely that the venom is evolving rapidly by prey-driven positive natural selection. Rather we contend that the venom has a defensive role deterring predation or harm from interspecific competition and overgrowth by fouling organisms. Factors influencing translation of toxin encoding genes perhaps warrants more profound experimental consideration. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1976-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ranko Gacesa
- Institute of Pharmaceutical Science, King's College London, 150 Stamford Street, London, SE1 9NH, UK
| | - Ray Chung
- Proteomics Facility, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, London, SE5 8AF, UK
| | - Simon R Dunn
- Coral Reefs Ecosystems Laboratory, School of Biological Sciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Andrew J Weston
- Mass Spectrometry Laboratory, UCL School of Pharmacy, 29/39 Brunswick Square, London, WC1N 1AX, UK
| | - Adrian Jaimes-Becerra
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua Matao, Trav. 14, 101, 05508-090, São Paulo, SP, Brazil
| | - Antonio C Marques
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua Matao, Trav. 14, 101, 05508-090, São Paulo, SP, Brazil.,Centro de Biologia Marinha, Universidade de São Paulo, Rodovia Manoel Hypólito do Rego, km. 131,5, 11600-000, São Sebastião, Brazil
| | - André C Morandini
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua Matao, Trav. 14, 101, 05508-090, São Paulo, SP, Brazil
| | - Daslav Hranueli
- Section for Bioinformatics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Antonio Starcevic
- Section for Bioinformatics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000, Zagreb, Croatia
| | - Malcolm Ward
- Proteomics Facility, Institute of Psychiatry, Psychology & Neuroscience, King's College London, 16 De Crespigny Park, London, SE5 8AF, UK
| | - Paul F Long
- Institute of Pharmaceutical Science, King's College London, 150 Stamford Street, London, SE1 9NH, UK. .,Department of Chemistry, King's College London, Strand, London, WC2R 2LS, UK. .,Brazil Institute, King's College London, Strand, London, WC2R 2LS, UK. .,Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 580, B16, 05508-000, São Paulo, SP, Brazil.
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Brinkman DL, Jia X, Potriquet J, Kumar D, Dash D, Kvaskoff D, Mulvenna J. Transcriptome and venom proteome of the box jellyfish Chironex fleckeri. BMC Genomics 2015; 16:407. [PMID: 26014501 PMCID: PMC4445812 DOI: 10.1186/s12864-015-1568-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 04/23/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The box jellyfish, Chironex fleckeri, is the largest and most dangerous cubozoan jellyfish to humans. It produces potent and rapid-acting venom and its sting causes severe localized and systemic effects that are potentially life-threatening. In this study, a combined transcriptomic and proteomic approach was used to identify C. fleckeri proteins that elicit toxic effects in envenoming. RESULTS More than 40,000,000 Illumina reads were used to de novo assemble ∼ 34,000 contiguous cDNA sequences and ∼ 20,000 proteins were predicted based on homology searches, protein motifs, gene ontology and biological pathway mapping. More than 170 potential toxin proteins were identified from the transcriptome on the basis of homology to known toxins in publicly available sequence databases. MS/MS analysis of C. fleckeri venom identified over 250 proteins, including a subset of the toxins predicted from analysis of the transcriptome. Potential toxins identified using MS/MS included metalloproteinases, an alpha-macroglobulin domain containing protein, two CRISP proteins and a turripeptide-like protease inhibitor. Nine novel examples of a taxonomically restricted family of potent cnidarian pore-forming toxins were also identified. Members of this toxin family are potently haemolytic and cause pain, inflammation, dermonecrosis, cardiovascular collapse and death in experimental animals, suggesting that these toxins are responsible for many of the symptoms of C. fleckeri envenomation. CONCLUSIONS This study provides the first overview of a box jellyfish transcriptome which, coupled with venom proteomics data, enhances our current understanding of box jellyfish venom composition and the molecular structure and function of cnidarian toxins. The generated data represent a useful resource to guide future comparative studies, novel protein/peptide discovery and the development of more effective treatments for jellyfish stings in humans. (Length: 300).
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Affiliation(s)
- Diane L Brinkman
- Australian Institute of Marine Science, Townsville, QLD, Australia.
| | - Xinying Jia
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
| | - Jeremy Potriquet
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
| | - Dhirendra Kumar
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia. .,G.N. Ramachandran Knowledge Center for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.
| | - Debasis Dash
- G.N. Ramachandran Knowledge Center for Genome Informatics, CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.
| | - David Kvaskoff
- The University of Queensland Centre for Clinical Research, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia.
| | - Jason Mulvenna
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia. .,The University of Queensland, School of Biomedical Sciences, Brisbane, QLD, Australia.
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8
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Hargreaves AD, Swain MT, Hegarty MJ, Logan DW, Mulley JF. Restriction and recruitment-gene duplication and the origin and evolution of snake venom toxins. Genome Biol Evol 2015; 6:2088-95. [PMID: 25079342 PMCID: PMC4231632 DOI: 10.1093/gbe/evu166] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Snake venom has been hypothesized to have originated and diversified through a process that involves duplication of genes encoding body proteins with subsequent recruitment of the copy to the venom gland, where natural selection acts to develop or increase toxicity. However, gene duplication is known to be a rare event in vertebrate genomes, and the recruitment of duplicated genes to a novel expression domain (neofunctionalization) is an even rarer process that requires the evolution of novel combinations of transcription factor binding sites in upstream regulatory regions. Therefore, although this hypothesis concerning the evolution of snake venom is very unlikely and should be regarded with caution, it is nonetheless often assumed to be established fact, hindering research into the true origins of snake venom toxins. To critically evaluate this hypothesis, we have generated transcriptomic data for body tissues and salivary and venom glands from five species of venomous and nonvenomous reptiles. Our comparative transcriptomic analysis of these data reveals that snake venom does not evolve through the hypothesized process of duplication and recruitment of genes encoding body proteins. Indeed, our results show that many proposed venom toxins are in fact expressed in a wide variety of body tissues, including the salivary gland of nonvenomous reptiles and that these genes have therefore been restricted to the venom gland following duplication, not recruited. Thus, snake venom evolves through the duplication and subfunctionalization of genes encoding existing salivary proteins. These results highlight the danger of the elegant and intuitive “just-so story” in evolutionary biology.
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Affiliation(s)
| | - Martin T Swain
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, United Kingdom
| | - Matthew J Hegarty
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, United Kingdom
| | - Darren W Logan
- Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - John F Mulley
- School of Biological Sciences, Bangor University, United Kingdom
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Verhoef D, Yang X, Parthasarathy S, Reitsma PH, Camire RM, Bos MHA. Functional implications of the unique disulfide bond in venom factor V from the Australian common brown snakePseudonaja textilis. TOXIN REV 2013. [DOI: 10.3109/15569543.2013.844712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Wong ES, Belov K. Venom evolution through gene duplications. Gene 2012; 496:1-7. [DOI: 10.1016/j.gene.2012.01.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Revised: 01/10/2012] [Accepted: 01/10/2012] [Indexed: 12/30/2022]
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Wong ESW, Papenfuss AT, Whittington CM, Warren WC, Belov K. A limited role for gene duplications in the evolution of platypus venom. Mol Biol Evol 2011; 29:167-77. [PMID: 21816864 DOI: 10.1093/molbev/msr180] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Gene duplication followed by adaptive selection is believed to be the primary driver of venom evolution. However, to date, no studies have evaluated the importance of gene duplications for venom evolution using a genomic approach. The availability of a sequenced genome and a venom gland transcriptome for the enigmatic platypus provides a unique opportunity to explore the role that gene duplication plays in venom evolution. Here, we identify gene duplication events and correlate them with expressed transcripts in an in-season venom gland. Gene duplicates (1,508) were identified. These duplicated pairs (421), including genes that have undergone multiple rounds of gene duplications, were expressed in the venom gland. The majority of these genes are involved in metabolism and protein synthesis not toxin functions. Twelve secretory genes including serine proteases, metalloproteinases, and protease inhibitors likely to produce symptoms of envenomation such as vasodilation and pain were detected. Only 16 of 107 platypus genes with high similarity to known toxins evolved through gene duplication. Platypus venom C-type natriuretic peptides and nerve growth factor do not possess lineage-specific gene duplicates. Extensive duplications, believed to increase the potency of toxic content and promote toxin diversification, were not found. This is the first study to take a genome-wide approach in order to examine the impact of gene duplication on venom evolution. Our findings support the idea that adaptive selection acts on gene duplicates to drive the independent evolution and functional diversification of similar venom genes in venomous species. However, gene duplications alone do not explain the "venome" of the platypus. Other mechanisms, such as alternative splicing and mutation, may be important in venom innovation.
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Affiliation(s)
- Emily S W Wong
- Faculty of Veterinary Science, The University of Sydney, Sydney, New South Wales, Australia.
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Kang TS, Georgieva D, Genov N, Murakami MT, Sinha M, Kumar RP, Kaur P, Kumar S, Dey S, Sharma S, Vrielink A, Betzel C, Takeda S, Arni RK, Singh TP, Kini RM. Enzymatic toxins from snake venom: structural characterization and mechanism of catalysis. FEBS J 2011; 278:4544-76. [PMID: 21470368 DOI: 10.1111/j.1742-4658.2011.08115.x] [Citation(s) in RCA: 185] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Snake venoms are cocktails of enzymes and non-enzymatic proteins used for both the immobilization and digestion of prey. The most common snake venom enzymes include acetylcholinesterases, l-amino acid oxidases, serine proteinases, metalloproteinases and phospholipases A(2) . Higher catalytic efficiency, thermal stability and resistance to proteolysis make these enzymes attractive models for biochemists, enzymologists and structural biologists. Here, we review the structures of these enzymes and describe their structure-based mechanisms of catalysis and inhibition. Some of the enzymes exist as protein complexes in the venom. Thus we also discuss the functional role of non-enzymatic subunits and the pharmacological effects of such protein complexes. The structures of inhibitor-enzyme complexes provide ideal platforms for the design of potent inhibitors which are useful in the development of prototypes and lead compounds with potential therapeutic applications.
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Affiliation(s)
- Tse Siang Kang
- Department of Pharmacy, National University of Singapore, Singapore
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Procoagulant adaptation of a blood coagulation prothrombinase-like enzyme complex in australian elapid venom. Toxins (Basel) 2010; 2:1554-67. [PMID: 21127733 PMCID: PMC2994417 DOI: 10.3390/toxins2061554] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/04/2010] [Accepted: 06/17/2010] [Indexed: 11/17/2022] Open
Abstract
The macromolecular enzyme complex prothrombinase serves an indispensable role in blood coagulation as it catalyzes the conversion of prothrombin to thrombin, a key regulatory enzyme in the formation of a blood clot. Interestingly, a virtually identical enzyme complex is found in the venom of some Australian elapid snakes, which is composed of a cofactor factor Va-component and a serine protease factor Xa-like subunit. This review will provide an overview of the identification and characterization of the venom prothrombinase complex and will discuss the rationale for its powerful procoagulant nature responsible for the potent hemostatic toxicity of the elapid venom.
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15
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Reza A, Kini RM. PROTHROMBIN ACTIVATORS FROM AUSTRALIAN SNAKES. TOXIN REV 2008. [DOI: 10.1080/15569540600567313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Zhu H, Toso R, Camire RM. Inhibitory sequences within the B-domain stabilize circulating factor V in an inactive state. J Biol Chem 2007; 282:15033-9. [PMID: 17387173 DOI: 10.1074/jbc.m701315200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Blood coagulation factor V circulates as a procofactor with little or no procoagulant activity. It is activated to factor Va by thrombin following proteolytic removal of a large central B-domain. Although this reaction is well studied, the mechanism by which bond cleavage and B-domain release facilitate the transition to the active cofactor state has not been defined. Here we show that deletion or substitution of specific B-domain sequences drives the expression of procoagulant function without the need for proteolytic processing. Conversion to the constitutively active cofactor state is related, at least in part, to a cluster of amino acids that is highly basic and well conserved across the vertebrate lineage. Our findings demonstrate that discrete sequences in the B-domain serve to stabilize the inactive procofactor state, with proteolysis primarily functioning to remove these inhibitory constraints. These unexpected results provide new insight into the mechanism of factor V activation.
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Affiliation(s)
- Hua Zhu
- Department of Pediatrics, Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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17
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Reza MA, Swarup S, Kini RM. Structure of two genes encoding parallel prothrombin activators in Tropidechis carinatus snake: gene duplication and recruitment of factor X gene to the venom gland. J Thromb Haemost 2007; 5:117-26. [PMID: 17239167 DOI: 10.1111/j.1538-7836.2006.02266.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Proteins with new function originate through gene duplication followed by divergence. In nature, occurrence of structurally and functionally similar proteins performing highly diverse physiological roles within an organism is rare. Several Australian elapid snakes have two parallel prothrombin activating systems with distinct physiological roles. For example, in Tropidechis carinatus, trocarin D exists in the venom and acts as toxin, whereas coagulation factor (F) X exists in plasma and plays a role in hemostasis. RESULTS Here, we show that FX and the trocarin D genes are expressed in a highly tissue-specific manner in T. carinatus. To understand their origin, recruitment and evolution, we determined the complete structure of their genes. Both genes have eight exons with identical exon-intron boundaries. All the introns are 92-99% identical with the exception of intron 1, indicating a recent gene duplication event. The first intron of the trocarin D gene is also nearly identical to that of the FX gene, except for two deletions (255 and 1406 bp) and three insertions (214, 1975, and 2174 bp). The third insertion has a potential scaffold/matrix attached region. The putative promoter of the snake FX gene shares similar cis-elements compared with those of human and murine FX genes. Interestingly, the trocarin D promoter has a 264-bp insertion with core promoter sequences and cis-elements that are known to induce high-level expression. This insertion might be responsible for switching from constitutive expression of the FX gene to inducible expression of trocarin D. Thus, we named this segment as VERSE (Venom Recruitment/Switch Element). CONCLUSION To our knowledge, this is the first molecular evidence for the recruitment of a duplicated gene for expression in venom glands by a simple insertion.
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Affiliation(s)
- M A Reza
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
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18
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Reza MA, Minh Le TN, Swarup S, Manjunatha Kini R. Molecular evolution caught in action: gene duplication and evolution of molecular isoforms of prothrombin activators in Pseudonaja textilis (brown snake). J Thromb Haemost 2006; 4:1346-53. [PMID: 16706981 DOI: 10.1111/j.1538-7836.2006.01969.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The evolution of structurally and functionally similar proteins with highly diverse physiological roles within a single organism is of great interest. Australian elapid snakes offer an excellent opportunity to study the molecular evolution of prothrombin activators. Venom from Pseudonaja textilis contains pseutarin C, a group C prothrombin activator. Its enzymatic subunit is structurally and functionally similar to mammalian factor (F) Xa, whereas its non-enzymatic subunit is similar to FVa. As vertebrates, the snakes also contain a system to activate prothrombin in their own blood during injury. These hemostatic factors are produced in the liver. RESULTS Here we describe the presence of two molecular forms of FX expressed in the liver of P. textilis. Both isoforms have molecular signatures and domain architecture of FX. However, one isoform shows approximately 94% sequence identity with the snake FX from Tropidechis carinatus, whereas the other is much closer (90% identity) to the catalytic subunit of pseutarin C (PCCS). Real-time polymerase chain reaction reveals that the latter isoform is expressed approximately 56 000 times lower in the liver of P. textilis. However, the isoforms are not expressed in the venom gland. CONCLUSION A detailed analysis of deletions and insertions along with the sequence indicates that the second isoform is an intermediate caught in the evolution of venom prothrombin activator from the blood coagulation FX. Thus, this isoform represents a 'molecular fossil' and reveals the likely evolutionary path of recruitment of FX in the venom gland.
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Affiliation(s)
- M A Reza
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
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