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Two Distinct Superoxidase Dismutases (SOD) Secreted by the Helminth Parasite Fasciola hepatica Play Roles in Defence against Metabolic and Host Immune Cell-Derived Reactive Oxygen Species (ROS) during Growth and Development. Antioxidants (Basel) 2022; 11:antiox11101968. [PMID: 36290692 PMCID: PMC9598480 DOI: 10.3390/antiox11101968] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
The antioxidant superoxide dismutase (SOD) catalyses the dismutation of superoxide, a dangerous oxygen free radical, into hydrogen peroxide and molecular oxygen. Superoxide generation during the oxidative burst of the innate immune system is considered a key component of the host defence against invading pathogens. We demonstrate the presence and differential expression of two SODs in Fasciola hepatica, a leaderless cytosolic (FhSOD1) and an extracellular (FhSOD3) form containing a secretory signal peptide, suggesting that the parasites exploit these enzymes in distinct ways to counteract reactive oxygen species (ROS) produced by cellular metabolism and immune defences. Both enzymes are highly expressed by the infective newly excysted juvenile (NEJ) stages and are found in abundance in their excretory–secretory products (ES), but only FhSOD1 is present in adult ES, suggesting that the antioxidants have different functions and pathways of secretion, and are under separate temporal expression control during the migration, growth, and development of the parasite. Functionally, the recombinant FhSOD1 and FhSOD3 exhibit similar activity against superoxide to their mammalian counterparts. Confocal immuno-localisation studies demonstrated the presence of FhSOD1 and FhSOD3 on the NEJ tegument and parenchyma, supporting our suggestion that these enzymes are secreted during host invasion to protect the parasites from the harmful oxidative bursts produced by the activated innate immune response. By producing superoxide enzymatically in vitro, we were able to demonstrate robust killing of F. hepatica NEJ within 24 h post-excystment, and that the lethal effect of ROS was nullified with the addition of SOD and catalase (the antioxidant enzyme responsible for the dismutation of hydrogen peroxide, a by-product of the SOD reaction). This study further elucidates the mechanism by which F. hepatica protects against ROS derived from cellular metabolism and how the parasite could mitigate damage caused by the host’s immune response to benefit its survival.
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Moustafa A, Perbandt M, Liebau E, Betzel C, Falke S. Crystal structure of an extracellular superoxide dismutase from Onchocerca volvulus and implications for parasite-specific drug development. Acta Crystallogr F Struct Biol Commun 2022; 78:232-240. [PMID: 35647680 PMCID: PMC9158661 DOI: 10.1107/s2053230x22005350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 05/19/2022] [Indexed: 11/17/2022] Open
Abstract
Superoxide dismutases (SODs) are metalloproteins that are responsible for the dismutation of superoxide anion radicals. SODs are consequently protective against oxidative damage to cellular components. Among other protective mechanisms, the filarial parasite Onchocerca volvulus has a well developed defense system to scavenge toxic free radicals using SODs during migration and sojourning of the microfilariae and adult worms in the human body. O. volvulus is responsible for the neglected disease onchocerciasis or `river blindness'. In the present study, an extracellular Cu/Zn-SOD from O. volvulus (OvEC-SOD) was cloned, purified and crystallized to obtain structural insight into an attractive drug target with the potential to combat onchocerciasis. The recombinant OvEC-SOD forms a dimer and the protein structure was solved and refined to 1.55 Å resolution by X-ray crystallography. Interestingly, a sulfate ion supports the coordination of the conserved copper ion. The overall protein shape was verified by small-angle X-ray scattering. The enzyme shows a different surface charge distribution and different termini when compared with the homologous human SOD. A distinct hydrophobic cleft to which both protomers of the dimer contribute was utilized for a docking approach with compounds that have previously been identified as SOD inhibitors to highlight the potential for individual structure-based drug development.
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Affiliation(s)
- Amr Moustafa
- Laboratory for Structural Biology of Infection and Inflammation, University of Hamburg, c/o DESY, Building 22a, Notkestrasse 85, 22607 Hamburg, Germany
- Biochemistry Department, Faculty of Veterinary Medicine, Zagazig University, Zagazig 44519, Egypt
| | - Markus Perbandt
- Laboratory for Structural Biology of Infection and Inflammation, University of Hamburg, c/o DESY, Building 22a, Notkestrasse 85, 22607 Hamburg, Germany
| | - Eva Liebau
- Institut für Zoophysiologie, Westfälische Wilhelms-Universität Münster, Schlossplatz 8, 48143 Münster, Germany
| | - Christian Betzel
- Laboratory for Structural Biology of Infection and Inflammation, University of Hamburg, c/o DESY, Building 22a, Notkestrasse 85, 22607 Hamburg, Germany
| | - Sven Falke
- Laboratory for Structural Biology of Infection and Inflammation, University of Hamburg, c/o DESY, Building 22a, Notkestrasse 85, 22607 Hamburg, Germany
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Solo N, Kud J, Dandurand LM, Caplan A, Kuhl JC, Xiao F. Characterization of Superoxide Dismutase from the Potato Cyst Nematode, Globodera pallida. PHYTOPATHOLOGY 2021; 111:2110-2117. [PMID: 33754807 DOI: 10.1094/phyto-01-21-0021-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Potato cyst nematodes (PCNs), such as Globodera pallida and Globodera rostochiensis, are some of the most agriculturally and economically important pests of potato. Upon nematode infection, a principal component of plant defense is the generation of the reactive oxygen species (ROSs). ROSs are highly toxic molecules that cause damage to pathogens and host alike. To infect the plant, nematodes protect themselves from ROSs by activating their own antioxidant processes and ROS scavenging enzymes. One of these enzymes is a superoxide dismutase (SOD; EC 1.15.1.1), which prevents cellular damage by catalyzing conversion of the superoxide radical (O2-·) to hydrogen peroxide (H2O2) and molecular oxygen (O2). We have isolated a putatively secreted isoform of a Cu-Zn SOD (SOD-3) from G. pallida and localized the expression of this gene in the posterior region of the nematode. Furthermore, we studied the expression of the SOD-3 gene during early parasitic stages of infection (24 to 72 h) in the susceptible potato cultivar Desiree, the resistant potato cultivar Innovator, and an immune host, Solanum sisymbriifolium. The SOD-3 gene was significantly upregulated, regardless of the host type; however, the expression pattern differed between the susceptible and the resistant or immune hosts. This finding suggests that SOD-3 gene is responding to infection in plant roots differently depending on whether the nematode is experiencing a compatible or an incompatible interaction.
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Affiliation(s)
- Nejra Solo
- Department of Entomology, Plant Pathology, & Nematology, University of Idaho, Moscow, ID 83844
| | - Joanna Kud
- Department of Entomology, Plant Pathology, & Nematology, University of Idaho, Moscow, ID 83844
| | - Louise-Marie Dandurand
- Department of Entomology, Plant Pathology, & Nematology, University of Idaho, Moscow, ID 83844
| | - Allan Caplan
- Department of Plant Sciences, University of Idaho, Moscow, ID 83844
| | - Joseph C Kuhl
- Department of Plant Sciences, University of Idaho, Moscow, ID 83844
| | - Fangming Xiao
- Department of Plant Sciences, University of Idaho, Moscow, ID 83844
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Xu L, Yang J, Xu M, Shan D, Wu Z, Yuan D. Speciation and adaptive evolution reshape antioxidant enzymatic system diversity across the phylum Nematoda. BMC Biol 2020; 18:181. [PMID: 33243226 PMCID: PMC7694339 DOI: 10.1186/s12915-020-00896-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023] Open
Abstract
Background Nematodes have evolved to survive in diverse ecological niches and can be a serious burden on agricultural economy, veterinary medicine, and public health. Antioxidant enzymes in parasitic nematodes play a critical role in defending against host oxidative stress. However, the features of the evolution of antioxidant enzymes in the phylum Nematoda remain elusive. Results Here, we systematically investigated the evolution and gene expression of antioxidant enzymes in the genomes of 59 nematodes and transcriptomes of 20 nematodes. Catalase has been independently lost in several orders, suggesting that it is unnecessary for some nematodes. Unlike in mammals, phospholipid hydroperoxide glutathione peroxidase is widely distributed in nematodes, among which it has evolved independently. We found that superoxide dismutase (SOD) has been present throughout nematode evolutionary process, and the extracellular isoform (SOD3) is diverged from the corresponding enzyme in mammals and has undergone duplication and differentiation in several nematodes. Moreover, the evolution of intracellular and extracellular SOD isoforms in filaria strongly indicates that extracellular SOD3 originated from intracellular SOD1 and underwent rapid evolution to form the diversity of extracellular SOD3. We identify a novel putative metal-independent extracellular SOD presenting independently in Steinernema and Strongyloididae lineage that featured a high expression level in Strongyloides larvae. Sequence divergence of SOD3 between parasitic nematodes and their closest free-living nematode, the specifically high expression in the parasitic female stage, and presence in excretory-secretory proteome of Strongyloides suggest that SOD3 may be related with parasitism. Conclusions This study advances our understanding of the complex evolution of antioxidant enzymes across Nematoda and provides targets for controlling parasitic nematode diseases.
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Affiliation(s)
- Lian Xu
- Key Laboratory of Neuroregeneration, Ministry of Education and Jiangsu Province, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.,Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jian Yang
- Key Laboratory of Neuroregeneration, Ministry of Education and Jiangsu Province, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Meng Xu
- Department of Ecology, Jinan University, Guangzhou, 510632, China
| | - Dai Shan
- BGI Genomics, BGI-Shenzhen, Shenzhen, 518083, China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| | - Dongjuan Yuan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, 510642, China.
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Yuan D, Luo S, Xu L, Zeng X, Wu Z. Regulatory effect of host miR-101b-3p on parasitism of nematode Angiostrongylus cantonensis via superoxide dismutase 3. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:557-566. [PMID: 30763737 DOI: 10.1016/j.bbagrm.2019.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/06/2019] [Accepted: 02/06/2019] [Indexed: 11/18/2022]
Abstract
MicroRNA plays a vital role in the regulation of host-parasite interaction. In recent years, genomic and transcriptomic resources have become increasingly available for many helminths, but only a limited number of reports in this area are on the regulatory effects of host microRNAs on parasitic nematodes. In this work, we screened increased expression of host microRNAs after nematode infection from miRNA-seq data and predicted target genes by combined bioinformatics analysis and transcriptional profiling. We elucidated regulatory effects of one host miRNA on nematode infection using miRNA inhibitor and adeno-associated virus (AAV)-based TuD miRNA inhibitor. Using AAV-based TuD miRNA inhibitor, we showed that stable blockade of mmu-miR-101b-3p could alleviate the pathological damages of Angiostrongylus cantonensis, a parasitic nematode. Data from a luciferase report assay showed that mmu-miR-101b-3p targeted the extracellular superoxide dismutase 3 (Acsod3). Increased Acsod3 expression in larvae and alleviated oxidative damages were seen in the groups receiving mmu-miR-101b-3p inhibitor treatment in vitro and AAV-based TuD miRNA inhibitor injection in vivo. Results of this study demonstrate that murine miR-101b-3p inhibits the expression of antioxidant enzyme in A. cantonensis to strengthen host oxidative responses to nematodes. This work expands our knowledge of interspecies regulation of nematode gene expression by of host miRNAs.
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Affiliation(s)
- Dongjuan Yuan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China; Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Shiqi Luo
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory for Tropical Diseases Control (SYSU), Ministry of Education, Guangzhou 510080, China; Provincial Engineering Technology Research Center for Diseases-vectors Control, Guangdong, Guangzhou 510080, China; Institute of Virology, Technical University of Munich/Helmholtz Zentrum München, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany
| | - Lian Xu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory for Tropical Diseases Control (SYSU), Ministry of Education, Guangzhou 510080, China; Provincial Engineering Technology Research Center for Diseases-vectors Control, Guangdong, Guangzhou 510080, China
| | - Xingda Zeng
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory for Tropical Diseases Control (SYSU), Ministry of Education, Guangzhou 510080, China; Provincial Engineering Technology Research Center for Diseases-vectors Control, Guangdong, Guangzhou 510080, China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory for Tropical Diseases Control (SYSU), Ministry of Education, Guangzhou 510080, China; Provincial Engineering Technology Research Center for Diseases-vectors Control, Guangdong, Guangzhou 510080, China.
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Isolation and characterization of Cu/Zn–superoxide dismutase in Fasciola gigantica. Exp Parasitol 2015; 151-152:1-7. [DOI: 10.1016/j.exppara.2015.01.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/23/2015] [Accepted: 01/27/2015] [Indexed: 11/17/2022]
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Ajonina-Ekoti I, Ndjonka D, Tanyi MK, Wilbertz M, Younis AE, Boursou D, Kurosinski MA, Eberle R, Lüersen K, Perbandt M, Breloer M, Brattig NW, Liebau E. Functional characterization and immune recognition of the extracellular superoxide dismutase from the human pathogenic parasite Onchocerca volvulus (OvEC-SOD). Acta Trop 2012; 124:15-26. [PMID: 22677600 DOI: 10.1016/j.actatropica.2012.05.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 05/23/2012] [Accepted: 05/28/2012] [Indexed: 01/04/2023]
Abstract
Onchocerca volvulus is a human pathogenic filarial nematode causing chronic onchocerciasis, a disease characterized by chronic skin and eye lesions. Despite attempts to control this infection from many perspectives, it still remains a threat to public health because of adverse effects of available drugs and recent reports of drug resistance. Under control of an intact immune system, O. volvulus survives for a long time in the host by employing a variety of strategies including the utility of antioxidant enzymes. In the present study, we focus on the extracellular superoxide dismutase from O. volvulus (OvEC-SOD) found in the excretory/secretory products of adult worms. Contrary to previous studies, the OvEC-SOD was found to have a 19 amino acid long signal peptide that is cleaved off during the process of maturation. To validate this result, we designed a novel method based on Caenorhabditis elegans cup5(ar465) mutants to specifically evaluate signal peptide-mediated secretion of nematodal proteins. Following purification, the recombinant OvEC-SOD was active as a dimer. Site-directed mutagenesis of the three cysteines present in the OvEC-SOD shows that enzyme activity is markedly reduced in the Cys-192 mutant. A homology model of the OvEC-SOD underlines the importance of Cys-192 for the stabilization of the adjacent active site channel. The generation of a humoral immune response to secretory OvEC-SOD was indicated by demonstrating IgG reactivity in sera from patients infected with O. volvulus while the cross-reactivity of IgG in plasma samples from cows, infected with the most closely related parasite Onchocerca ochengi, occurred only marginally. High IgG1 and IgM titres were recorded in sera from mice infected with the filaria Litomosoides sigmodontis, however, low or no cellular proliferative responses were observed. Thus, the present data suggest that secretory OvEC-SOD is a target of the humoral immune response in human onchocerciasis and induced strongest IgG responses in hyperreactive onchocerciasis. Furthermore, humoral response during murine infection induced SOD-specific IgG that cross-reacted with OvEC-SOD.
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Li AH, Na BK, Ahn SK, Cho SH, Pak JH, Park YK, Kim TS. Functional expression and characterization of a cytosolic copper/zinc-superoxide dismutase of Spirometra erinacei. Parasitol Res 2010; 106:627-35. [PMID: 20076970 DOI: 10.1007/s00436-009-1714-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 12/17/2009] [Indexed: 11/26/2022]
Abstract
Spirometra erinacei is a pseudophyllidean tapeworm which inhabits the intestines of cats and dogs. The infections are usually asymptomatic in these animals, but the infection of the plerocercoid larvae of the parasite, spargana, cause sparganosis in other vertebrates, including human. In this study, we identified a gene encoding the copper/zinc-superoxide dismutase of S. erinacei (SeCuZn-SOD) and partially characterized the biochemical and functional properties of the enzyme. The open reading frame of SeCuZnSOD was 465 bp that encodes 154 amino acids. The characteristic amino acid residues and motifs required for coordinating copper and zinc enzymatic function were well conserved. The genomic length of the SeCuZnSOD was 1,985 bp consisting of three exons that are separated by two introns. SeCuZnSOD is a typical cytosolic form which shares similar biochemical properties, including broad pH optima and inhibition profile by KCN and H(2)O(2), with cytosolic Cu/Zn-SODs of other organisms. SeCuZnSOD was functionally expressed in both S. erinacei plerocercoid larvae and adult worms, and its expression level was significantly increased when the plerocercoid larvae were treated with paraquat. The enzyme may play essential roles for survival of the parasite not only by protecting itself from endogenous oxidative stress, but also by detoxifying oxidative killing of the parasite by host immune effector cells.
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Affiliation(s)
- Ai-Hua Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
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9
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Lee WG, Hwang JH, Na BK, Cho JH, Lee HW, Cho SH, Kong Y, Song CY, Kim TS. Functional expression of a recombinant copper/zinc superoxide dismutase of filarial nematode, Brugia malayi. J Parasitol 2005; 91:205-8. [PMID: 15856906 DOI: 10.1645/ge-285r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A gene encoding a copper/zinc superoxide dismutase (Cu/ Zn-SOD) of a filarial nematode, Brugia malayi, has been isolated and the biochemical properties of a functionally expressed recombinant enzyme were investigated. The cloned complementary DNA contained a single open reading frame of 477 bp encoding 158 amino acids (aa), which conserved metal-binding residues as well as residues specific for Cu/Zn-SODs. Comparison of the deduced aa sequence of the enzyme with that of other helminthes species, including filarial worms, exhibited high degree of similarities (49-98%). Recombinant enzyme of 32 kDa had an isoelectric point of 6.6 and was shown to consist of 2 subunits linked by interchain disulfide bonds. Enzyme activity of the recombinant protein was inhibited by potassium cyanide and hydrogen peroxide but not by sodium azide. It showed a wide range of pH optima, i.e., 7.0-11.0 and was highly resistant to heat inactivation.
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Affiliation(s)
- W G Lee
- Department of Tropical and Endemic Parasitic Diseases, National Institute of Health, Seoul 122-701, Korea
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10
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Dalton JP, Brindley PJ, Knox DP, Brady CP, Hotez PJ, Donnelly S, O'Neill SM, Mulcahy G, Loukas A. Helminth vaccines: from mining genomic information for vaccine targets to systems used for protein expression. Int J Parasitol 2003; 33:621-40. [PMID: 12782060 DOI: 10.1016/s0020-7519(03)00057-2] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The control of helminth diseases of people and livestock continues to rely on the widespread use of anti-helminthic drugs. However, concerns with the appearance of drug resistant parasites and the presence of pesticide residues in food and the environment, has given further incentive to the goal of discovering molecular vaccines against these pathogens. The exponential rate at which gene and protein sequence information is accruing for many helminth parasites requires new methods for the assimilation and analysis of the data and for the identification of molecules capable of inducing immunological protection. Some promising vaccine candidates have been discovered, in particular cathepsin L proteases from Fasciola hepatica, aminopeptidases from Haemonchus contortus, and aspartic proteases from schistosomes and hookworms, all of which are secreted into the host tissues or into the parasite intestine where they play important roles in host-parasite interactions. Since secreted proteins, in general, are exposed to the immune system of the host they represent obvious candidates at which vaccines could be targeted. Therefore, in this article, we consider the potential values and uses of algorithms for characterising cDNAs amongst the collated helminth genomic information that encode secreted proteins, and methods for their selective isolation and cloning. We also review the variety of prokaryotic and eukaryotic cell expression systems that have been employed for the production and downstream purification of recombinant proteins in functionally active form, and provide an overview of the parameters that must be considered if these recombinant proteins are to be commercialised as vaccine therapeutics in humans and/or animals.
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Affiliation(s)
- John P Dalton
- School of Biotechnology, Dublin City University, Glasnevin, Dublin 9, Ireland.
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11
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Schott EJ, Robledo JAF, Wright AC, Silva AM, Vasta GR. Gene organization and homology modeling of two iron superoxide dismutases of the early branching protist Perkinsus marinus. Gene 2003; 309:1-9. [PMID: 12727353 DOI: 10.1016/s0378-1119(03)00469-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The facultative intracellular oyster parasite, Perkinsus marinus, taxonomically related to both dinoflagellates and apicomplexans, possesses at least two distinct genes (PmSOD1 and PmSOD2) predicted to encode iron-containing superoxide dismutases (FeSOD). DNA blots and sequence analysis suggest that both PmSOD1 and PmSOD2 are single copy and are unlinked. PmSOD1 and PmSOD2 are composed of five and six exons, respectively. All introns are delimited by canonical GT/AG boundaries, and have some features more similar to apicomplexan than dinoflagellate introns. Interestingly, exon 1 of PmSOD2 encodes putative transmembrane and spacer domains with no homology to FeSODs, while exon 2 begins with a methionine codon and is homologous to the N-terminus of FeSODs. The position of introns is not highly conserved between PmSOD1 and PmSOD2, although one intron is in a similar location. Comparison of the intron positions of PmSOD1 and PmSOD2 to those of available apicomplexan FeSODs shows that the intron position shared by PmSOD1 and PmSOD2 is also observed in the FeSOD of Toxoplasma gondii. Comparison of the untranscribed regions 5' and 3' of the coding regions for PmSOD1 and PmSOD2 reveals few motifs in common. Instead, each gene possesses a distinct set of putative upstream transcription factor binding sites. Although the proteins encoded by PmSOD1 and PmSOD2 are only 38% identical to each other, homology modeling indicates that they have nearly identical active site structures. The divergent genomic organizations of two FeSOD genes in the same organism illustrates the complexity of the antioxidant system of even simple, early-branching protists such as P. marinus.
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Affiliation(s)
- Eric J Schott
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 East Pratt Street, Baltimore, MD 21202, USA
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12
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Abstract
Host immune responses limit, and in some instances eliminate, nematode infections. There is considerable interest in enhancing these natural processes by the use of antinematode vaccines to achieve control of infection or disease. How nematodes are damaged is unclear. Worms might be damaged directly by effector cells and molecules of the immune system. Alternatively, they might be damaged by the physiological stress of their efforts to resist attack. Separating these possibilities could have important implications for approaches to the control of nematode infections and the disease that they cause.
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Affiliation(s)
- Mark Viney
- School of Biological Sciences, University of Bristol, Woodland Rd, BS8 1UG, Bristol, UK.
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13
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Liebau E, Eschbach ML, Tawe W, Sommer A, Fischer P, Walter RD, Henkle-Dührsen K. Identification of a stress-responsive Onchocerca volvulus glutathione S-transferase (Ov-GST-3) by RT-PCR differential display. Mol Biochem Parasitol 2000; 109:101-10. [PMID: 10960169 DOI: 10.1016/s0166-6851(00)00232-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of oxidative insult on gene transcript levels in the filarial nematode Onchocerca volvulus were investigated using differential display RT-PCR. Oxidative stress was applied with the reagents paraquat, plumbagin and xanthine-xanthine oxidase. In all three cases, a cDNA fragment encoding a novel glutathione S-transferase (GST) resembling members of the theta-class was identified as upregulated (PQ29, PG112, XOD26). The subsequently isolated full-length cDNA harbors a 753-bp open reading frame encoding a GST with 268 amino acid residues and a predicted molecular mass of 31 kDa. This stress-responsive GST (Ov-GST-3) possesses only 14 and 21% sequence identity with the other O. volvulus GSTs (Ov-GST-1 and Ov-GST-2, respectively). Interestingly, Ov-GST-3 shares higher sequence identity with GSTs that are upregulated due to environmental stress. In order to confirm the specific upregulation of the Ov-GST-3 transcripts identified by differential display and to analyze the mRNA levels of the other Ov-GSTs (Ov-GST-1 and Ov-GST-2) under elevated stress conditions, a semi-quantitative polymerase chain reaction-enzyme-linked immunosorbent assay was performed. The Ov-GST-3 gene transcript level increased dramatically in response to xanthine-xanthine oxidase and to a lesser extent with paraquat and plumbagin. In contrast, Ov-GST-1 and Ov-GST-2 did not show any significant alterations in their steady-state mRNA levels in response to oxidative stress when examining the same mRNA samples. The present study clearly demonstrates that Ov-GST-3 is a critical enzyme in the defense against oxidative stress.
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Affiliation(s)
- E Liebau
- Department of Biochemical Parasitology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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14
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Kim TS, Jung Y, Na BK, Kim KS, Chung PR. Molecular cloning and expression of Cu/Zn-containing superoxide dismutase from Fasciola hepatica. Infect Immun 2000; 68:3941-8. [PMID: 10858207 PMCID: PMC101671 DOI: 10.1128/iai.68.7.3941-3948.2000] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cytosolic superoxide dismutase (SOD) of Fasciola hepatica, a causative agent of fascioliasis, was purified and characterized. The enzyme consists of two identical subunits, each with an apparent molecular mass of 17.5 kDa. An analysis of the enzyme's primary structure and inhibition studies revealed that the enzyme is a copper/zinc-containing SOD (Cu/Zn-SOD). The enzyme activity was relatively stable in a broad pH range, from pH 7.0 to 10.0, and the enzyme showed maximum activity at pH 7.5. This enzyme also displayed strong antigenicity against sera of bovine and human subjects with fascioliasis. The SOD gene fragment was amplified by PCR with degenerate oligonucleotide primers derived from amino acid sequences conserved in the Cu/Zn-SODs of other organisms. An F. hepatica cDNA library was screened with the SOD gene fragment as a probe. As a result, a complete gene encoding the Cu/Zn-SOD was identified, and its nucleotide sequence was determined. The gene had an open reading frame of 438 bp and 146 deduced amino acids. Comparison of the deduced amino acid sequence of the enzyme with previously reported Cu/Zn-SOD amino acid sequences revealed considerably high homologies. The coding region of the F. hepatica Cu/Zn-SOD was cloned and expressed in Escherichia coli. Staining of native polyacrylamide gel for SOD activity of the expressed protein revealed SOD activity that was inactivated by potassium cyanide and hydrogen peroxide but not by sodium azide. This means that the presence of the recombinant fusion protein is indicative of Cu/Zn-SOD. The expressed protein also reacted with sera of bovine and human subjects with fascioliasis, but it did not react with sera of uninfected bovine and human subjects.
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Affiliation(s)
- T S Kim
- Department of Parasitology, National Institute of Health, Seoul 122-701, Korea
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Tawe W, Walter RD, Henkle-Dührsen K. Onchocerca volvulus superoxide dismutase genes: identification of functional promoters for pre-mRNA transcripts which undergo trans-splicing. Exp Parasitol 2000; 94:172-9. [PMID: 10831382 DOI: 10.1006/expr.2000.4488] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The genes encoding three forms of superoxide dismutase, the cytosolic and extracellular CuZn superoxide dismutases and the mitochondrial Mn superoxide dismutase, were isolated from an Onchocerca volvulus lambda fix II genomic library. Genomic Southern blot analyses indicate single-copy genes in the O. volvulus genome. The O. volvulus cytosolic and extracellular CuZnSOD genes (Ov-sod-1 and Ov-sod-2) are separated by 0.8 kb of sequence and are convergently transcribed. Since the transcripts from all three sod genes are trans-spliced, the transcription start point of each gene was determined in a heterologous system that lacks trans-splicing machinery by in vitro transcription using Drosophila embryo nuclear extracts, followed by primer extension experiments. The ability of the 5' flanking region of the genes encoding the three Ov-SODs to promote transcription was further examined in transient transfections of Chinese hamster ovary cells. In firefly luciferase reporter assays, the Ov-sod-1 and -2 and the MnSOD (Ov-sod-3) gene promoters showed minimal, strong, and moderate levels of activity in these cells, respectively. Both Ov-sod-2 and -3 gene promoter regions showed an initial increase in activity in response to 5' deletions. The results from the in vitro transcription experiments and the luciferase reporter assays were consistent and suggest the presence of Inr-like elements in the promoter regions of the Ov-sod genes.
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Affiliation(s)
- W Tawe
- Bernhard Nocht Institute for Tropical Medicine, Bernhard Nocht Str. 74, Hamburg, Germany
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Lattemann CT, Matzen A, Apfel H. Up-regulation of extracellular copper/zinc superoxide dismutase mRNA after transmission of the filarial parasite Acanthocheilonema viteae in the vertebrate host Meriones unguiculatus. Int J Parasitol 1999; 29:1437-46. [PMID: 10579430 DOI: 10.1016/s0020-7519(99)00073-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The gene encoding the cytoplasmic copper/zinc superoxide dismutase (AVSOD1) from the filarial parasite Acanthocheilonema viteae was isolated from a genomic DNA library using a degenerate oligonucleotide probe. Additionally, cDNAs of the AVSOD1 and the secreted extracellular SOD (AVSOD2) were both cloned by RT-PCR, and the AVSOD2 was expressed at high levels in E. coli. The amino acid sequence of the AVSOD1 is 89.5 and 87.5% identical to that of the corresponding enzymes of Brugia pahangi and Onchocerca volvulus, respectively. In contrast, the AVSOD2 shows a lower degree of identity to the other filarial SODs and is extensively glycosylated. RT-PCR studies demonstrate the expression of both SOD subtypes in all developmental stages of A. viteae and indicate up-regulation of the AVSOD2 expression after transmission from the vector to the definitive host. This suggests an enhanced requirement for SOD activity in post-infective larval stages and adults of A. viteae. ELISAs performed with purified recombinant AVSOD2 show that the AVSOD2 is not a major target for the immune system in naturally infected jirds.
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Affiliation(s)
- C T Lattemann
- Max-Planck-Institut für Biologie, Abteilung Infektionsbiologie, Tübingen, Germany
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Wildenburg G, Henkle-Dührsen K. Onchocerca volvulus: immunolocalization of the extracellular CuZn superoxide dismutase using antibodies raised against a 15-mer epitope of this enzyme. Exp Parasitol 1999; 91:1-6. [PMID: 9920037 DOI: 10.1006/expr.1999.4352] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The study describes the immunohistological localization of the extracellular CuZn superoxide dismutase (SOD2) in the parasitic nematode Onchocerca volvulus. Using specific antiserum raised against a 15-amino-acid peptide from the N-terminal region of the mature protein, this enzyme is detected primarily in the intestinal epithelium of the adult worms and to a lesser extent in the muscle cells of the uterine wall. A blocking experiment with the SOD2 peptide reduced the staining significantly, confirming specificity. The localization profile of SOD2 correlates extremely well with the localization of iron deposits in the gut and uterine muscle cells of adult O. volvulus. The detection of SOD2 in the functional intestine of O. volvulus, together with the evidence that it is a secreted protein, indicates that this enzyme in parasitic nematodes is in a position to interact with host molecules. It also demonstrates the accessibility of the parasite enzyme to an inhibitor or blocking antibody.
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Affiliation(s)
- G Wildenburg
- Department of Helminthology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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Selkirk ME, Smith VP, Thomas GR, Gounaris K. Resistance of filarial nematode parasites to oxidative stress. Int J Parasitol 1998; 28:1315-32. [PMID: 9770616 DOI: 10.1016/s0020-7519(98)00107-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
All filariae examined to date express a comprehensive repertoire of both cytoplasmic and secreted anti-oxidant enzymes, although significant differences exist between species and life-cycle stages. Adult Brugia malayi, Dirofilaria immitis and Onchocerca volvulus secrete CuZn superoxide dismutases, and the former two species also secrete a selenocysteine-independent glutathione peroxidase. This enzyme has been localised to the cuticular matrix of B. malayi, and the preferential reduction of fatty acid- and phospholipid hydroperoxides suggests that it may protect cuticular membranes from oxidative damage rather than directly metabolise hydrogen peroxide. Adult O. volvulus may compensate for an apparent deficiency in expression of this enzyme via a secreted variant of glutathione S-transferase. Recent studies have identified a highly expressed family of enzymes collectively termed peroxiredoxins, which most probably play an essential role in reduction of hydroperoxides. Data from cDNA cloning exercises indicate that all filarial species examined thus far express at least two peroxiredoxin variants which have been localised to diverse tissues. In-vitro studies have shown that B. malayi are particularly resistant to oxidative stress, and that the parasites do not rely solely on enzymatic mechanisms of defence. Cuticular lipids are relatively resistant to lipid peroxidation due to the low unsaturation indices of the constituent fatty acyl residues, but complete protection is afforded by the presence of alpha-tocopherol, presumably assimilated from host extracellular fluids. Brugia malayi are also relatively resistant to nitric oxide-mediated toxicity, and this may be due in part to incomplete dependence on aerobic metabolism. Little is known of potential mechanisms for detoxification of nitric oxide derivatives and adaptive responses to oxidative stress in general, and these represent goals for future research.
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Affiliation(s)
- M E Selkirk
- Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, U.K.
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