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A Tribute to a Bacillus thuringiensis Master: Professor David J. Ellar. Toxins (Basel) 2020; 12:toxins12120764. [PMID: 33287128 PMCID: PMC7761675 DOI: 10.3390/toxins12120764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 11/29/2020] [Indexed: 11/17/2022] Open
Abstract
This Special Issue, on Bacillus thuringiensis and its toxins, seems to be the right place to pay tribute to one of the most influential scientists in the field of research into this peculiar bacterium [...].
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Vílchez S. Making 3D-Cry Toxin Mutants: Much More Than a Tool of Understanding Toxins Mechanism of Action. Toxins (Basel) 2020; 12:toxins12090600. [PMID: 32948025 PMCID: PMC7551160 DOI: 10.3390/toxins12090600] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/15/2020] [Accepted: 08/20/2020] [Indexed: 12/21/2022] Open
Abstract
3D-Cry toxins, produced by the entomopathogenic bacterium Bacillus thuringiensis, have been extensively mutated in order to elucidate their elegant and complex mechanism of action necessary to kill susceptible insects. Together with the study of the resistant insects, 3D-Cry toxin mutants represent one of the pillars to understanding how these toxins exert their activity on their host. The principle is simple, if an amino acid is involved and essential in the mechanism of action, when substituted, the activity of the toxin will be diminished. However, some of the constructed 3D-Cry toxin mutants have shown an enhanced activity against their target insects compared to the parental toxins, suggesting that it is possible to produce novel versions of the natural toxins with an improved performance in the laboratory. In this report, all mutants with an enhanced activity obtained by accident in mutagenesis studies, together with all the variants obtained by rational design or by directed mutagenesis, were compiled. A description of the improved mutants was made considering their historical context and the parallel development of the protein engineering techniques that have been used to obtain them. This report demonstrates that artificial 3D-Cry toxins made in laboratories are a real alternative to natural toxins.
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Affiliation(s)
- Susana Vílchez
- Institute of Biotechnology, Department of Biochemistry and Molecular Biology I, Faculty of Science, University of Granada, 18071 Granada, Spain
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Bacterial Virus Lambda Gpd-Fusions to Cathelicidins, α- and β-Defensins, and Disease-Specific Epitopes Evaluated for Antimicrobial Toxicity and Ability to Support Phage Display. Viruses 2019; 11:v11090869. [PMID: 31533281 PMCID: PMC6784203 DOI: 10.3390/v11090869] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/05/2019] [Accepted: 09/12/2019] [Indexed: 11/23/2022] Open
Abstract
We showed that antimicrobial polypeptides, when translated as gene fusions to the bacteriophage lambda capsid decoration protein gpD, formed highly toxic molecules within E. coli, suggesting that they can retain their antimicrobial activity conformation when fused to gpD. These include gpD-fusions to human and porcine cathelicidins LL37 and PR39, β-defensins HBD3 and DEFB126-Δ (deleted for its many COOH-terminal glycosylation sites), and α-defensin HD5. Antimicrobial toxicity was only observed when the peptides were displayed from the COOH-terminal, and not the NH2-terminal end, of gpD. This suggests that COOH-terminal displayed polypeptides of gpD-fusions can more readily form an active-state conformation than when they are displayed from the NH2-terminal end of gpD. The high toxicity of the COOH-displayed gpD-defensins suggests either that the fused defensin peptides can be oxidized, forming three correct intramolecular disulfide bonds within the cytosol of bacterial cells, or that the versions without disulfide bonds are highly toxigenic. We showed the high efficiency of displaying single epitope 17 amino-acid fusions to gpD on LDP (lambda display particles), even when the gpD-fusion protein was toxic. The efficient formation of high display density LDP, displaying a single disease specific epitope (DSE), suggests the utility of LDP-DSE constructs for use as single epitope vaccines (SEV).
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Arab A, Nicastro J, Slavcev R, Razazan A, Barati N, Nikpoor AR, Brojeni AAM, Mosaffa F, Badiee A, Jaafari MR, Behravan J. Lambda phage nanoparticles displaying HER2-derived E75 peptide induce effective E75-CD8+ T response. Immunol Res 2017; 66:200-206. [DOI: 10.1007/s12026-017-8969-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Using phage display technology to obtain Crybodies active against non-target insects. Sci Rep 2017; 7:14922. [PMID: 29097681 PMCID: PMC5668233 DOI: 10.1038/s41598-017-09384-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 07/26/2017] [Indexed: 11/09/2022] Open
Abstract
The insecticidal Cry toxins produced by Bacillus thuringiensis (Bt) are increasingly important in the biological control of insect pests and vectors of human disease. Markets for Bt products and transgenic plants expressing their toxins are driven by their specificity, safety and the move away from chemical control agents. However, the high specificity of Cry toxins can also prove to be a limitation when there is no known Cry toxin active against a particular target. Novel activities can be discovered by screening natural Bt isolates or through modifications of the Cry proteins. Here we demonstrate the use of λ-phage displaying Cry1Aa13 toxin variants modified in domain II loop 2 (Crybodies) to select retargeted toxins. Through biopanning using gut tissue from larvae of the non-target insect Aedes aegypti, we isolated a number of phage for further testing. Two of the overexpressed Cry toxin variants showed significant activity against A. aegypti larvae while another induced mortality at the pupal stage. We present the first report of the use of phage display to identify novel activities toward insects from distant taxonomic Orders and establish this technology based on the use of Crybodies as a powerful tool for developing tailor-made insecticides against new target insects.
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Pacheco S, Cantón E, Zuñiga-Navarrete F, Pecorari F, Bravo A, Soberón M. Improvement and efficient display of Bacillus thuringiensis toxins on M13 phages and ribosomes. AMB Express 2015; 5:73. [PMID: 26606918 PMCID: PMC4659786 DOI: 10.1186/s13568-015-0160-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 11/04/2015] [Indexed: 11/10/2022] Open
Abstract
Bacillus thuringiensis (Bt) produces insecticidal proteins that have been used worldwide in the control of insect-pests in crops and vectors of human diseases. However, different insect species are poorly controlled by the available Bt toxins or have evolved resistance to these toxins. Evolution of Bt toxicity could provide novel toxins to control insect pests. To this aim, efficient display systems to select toxins with increased binding to insect membranes or midgut proteins involved in toxicity are likely to be helpful. Here we describe two display systems, phage display and ribosome display, that allow the efficient display of two non-structurally related Bt toxins, Cry1Ac and Cyt1Aa. Improved display of Cry1Ac and Cyt1Aa on M13 phages was achieved by changing the commonly used peptide leader sequence of the coat pIII-fusion protein, that relies on the Sec translocation pathway, for a peptide leader sequence that relies on the signal recognition particle pathway (SRP) and by using a modified M13 helper phage (Phaberge) that has an amber mutation in its pIII genomic sequence and preferentially assembles using the pIII-fusion protein. Also, both Cry1Ac and Cyt1Aa were efficiently displayed on ribosomes, which could allow the construction of large libraries of variants. Furthermore, Cry1Ac or Cyt1Aa displayed on M13 phages or ribosomes were specifically selected from a mixture of both toxins depending on which antigen was immobilized for binding selection. These improved systems may allow the selection of Cry toxin variants with improved insecticidal activities that could counter insect resistances.
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Bt toxin modification for enhanced efficacy. Toxins (Basel) 2014; 6:3005-27. [PMID: 25340556 PMCID: PMC4210883 DOI: 10.3390/toxins6103005] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 09/28/2014] [Accepted: 09/29/2014] [Indexed: 11/23/2022] Open
Abstract
Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance.
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Lucena WA, Pelegrini PB, Martins-de-Sa D, Fonseca FCA, Gomes JE, de Macedo LLP, da Silva MCM, Oliveira RS, Grossi-de-Sa MF. Molecular approaches to improve the insecticidal activity of Bacillus thuringiensis Cry toxins. Toxins (Basel) 2014; 6:2393-423. [PMID: 25123558 PMCID: PMC4147589 DOI: 10.3390/toxins6082393] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/23/2014] [Accepted: 06/27/2014] [Indexed: 02/01/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity.
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Affiliation(s)
- Wagner A. Lucena
- Embrapa Cotton, Campina Grande, 58428-095, PB, Brazil; E-Mail:
- Graduate Program in Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Patrícia B. Pelegrini
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Diogo Martins-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Fernando C. A. Fonseca
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Jose E. Gomes
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Leonardo L. P. de Macedo
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria Cristina M. da Silva
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Raquel S. Oliveira
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria F. Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
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Bacteriophage lambda display systems: developments and applications. Appl Microbiol Biotechnol 2014; 98:2853-66. [PMID: 24442507 DOI: 10.1007/s00253-014-5521-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 01/03/2014] [Accepted: 01/04/2014] [Indexed: 01/01/2023]
Abstract
Bacteriophage (phage) Lambda (λ) has played a key historic role in driving our understanding of molecular genetics. The lytic nature of λ and the conformation of its major capsid protein gpD in capsid assembly offer several advantages as a phage display candidate. The unique formation of the λ capsid and the potential to exploit gpD in the design of controlled phage decoration will benefit future applications of λ display where steric hindrance and avidity are of great concern. Here, we review the recent developments in phage display technologies with phage λ and explore some key applications of this technology including vaccine delivery, gene transfer, bio-detection, and bio-control.
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Construction and analysis of a genetically tuneable lytic phage display system. Appl Microbiol Biotechnol 2013; 97:7791-804. [PMID: 23640362 PMCID: PMC3745828 DOI: 10.1007/s00253-013-4898-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2013] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 12/03/2022]
Abstract
The Bacteriophage λ capsid protein gpD has been used extensively for fusion polypeptides that can be expressed from plasmids in Escherichia coli and remain soluble. In this study, a genetically controlled dual expression system for the display of enhanced green fluorescent protein (eGFP) was developed and characterized. Wild-type D protein (gpD) expression is encoded by λ Dam15 infecting phage particles, which can only produce a functional gpD protein when translated in amber suppressor strains of E. coli in the absence of complementing gpD from a plasmid. However, the isogenic suppressors vary dramatically in their ability to restore functional packaging to λDam15, imparting the first dimension of decorative control. In combination, the D-fusion protein, gpD::eGFP, was supplied in trans from a multicopy temperature-inducible expression plasmid, influencing D::eGFP expression and hence the availability of gpD::eGFP to complement for the Dam15 mutation and decorate viable phage progeny. Despite being the worst suppressor, maximal incorporation of gpD::eGFP into the λDam15 phage capsid was imparted by the SupD strain, conferring a gpDQ68S substitution, induced for plasmid expression of pD::eGFP. Differences in size, fluorescence and absolute protein decoration between phage preparations could be achieved by varying the temperature of and the suppressor host carrying the pD::eGFP plasmid. The effective preparation with these two variables provides a simple means by which to manage fusion decoration on the surface of phage λ.
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Fujii Y, Tanaka S, Otsuki M, Hoshino Y, Endo H, Sato R. Affinity Maturation of Cry1Aa Toxin to the Bombyx mori Cadherin-Like Receptor by Directed Evolution. Mol Biotechnol 2012; 54:888-99. [DOI: 10.1007/s12033-012-9638-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Teixeira Corrêa RF, Ardisson-Araújo DMP, Monnerat RG, Ribeiro BM. Cytotoxicity analysis of three Bacillus thuringiensis subsp. israelensis δ-endotoxins towards insect and mammalian cells. PLoS One 2012; 7:e46121. [PMID: 23029407 PMCID: PMC3448730 DOI: 10.1371/journal.pone.0046121] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 08/29/2012] [Indexed: 11/27/2022] Open
Abstract
Three members of the δ-endotoxin group of toxins expressed by Bacillus thuringiensis subsp. israelensis, Cyt2Ba, Cry4Aa and Cry11A, were individually expressed in recombinant acrystalliferous B. thuringiensis strains for in vitro evaluation of their toxic activities against insect and mammalian cell lines. Both Cry4Aa and Cry11A toxins, activated with either trypsin or Spodoptera frugiperda gastric juice (GJ), resulted in different cleavage patterns for the activated toxins as seen by SDS-PAGE. The GJ-processed proteins were not cytotoxic to insect cell cultures. On the other hand, the combination of the trypsin-activated Cry4Aa and Cry11A toxins yielded the highest levels of cytotoxicity to all insect cells tested. The combination of activated Cyt2Ba and Cry11A also showed higher toxic activity than that of toxins activated individually. When activated Cry4Aa, Cry11A and Cyt2Ba were used simultaneously in the same assay a decrease in toxic activity was observed in all insect cells tested. No toxic effect was observed for the trypsin-activated Cry toxins in mammalian cells, but activated Cyt2Ba was toxic to human breast cancer cells (MCF-7) when tested at 20 µg/mL.
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Affiliation(s)
| | | | - Rose Gomes Monnerat
- Embrapa – Recursos Genéticos e Biotecnologia, C.P. 02373, Brasília, Distrito Federal, Brazil
| | - Bergmann Morais Ribeiro
- Departamento de Biologia Celular, Universidade de Brasília, Brasília, Distrito Federal, Brazil
- * E-mail:
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Bravo A, Gómez I, Porta H, García-Gómez BI, Rodriguez-Almazan C, Pardo L, Soberón M. Evolution of Bacillus thuringiensis Cry toxins insecticidal activity. Microb Biotechnol 2012; 6:17-26. [PMID: 22463726 PMCID: PMC3815381 DOI: 10.1111/j.1751-7915.2012.00342.x] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Insecticidal Cry proteins produced by Bacillus thuringiensis are use worldwide in transgenic crops for efficient pest control. Among the family of Cry toxins, the three domain Cry family is the better characterized regarding their natural evolution leading to a large number of Cry proteins with similar structure, mode of action but different insect specificity. Also, this group is the better characterized regarding the study of their mode of action and the molecular basis of insect specificity. In this review we discuss how Cry toxins have evolved insect specificity in nature and analyse several cases of improvement of Cry toxin action by genetic engineering, some of these examples are currently used in transgenic crops. We believe that the success in the improvement of insecticidal activity by genetic evolution of Cry toxins will depend on the knowledge of the rate-limiting steps of Cry toxicity in different insect pests, the mapping of the specificity binding regions in the Cry toxins, as well as the improvement of mutagenesis strategies and selection procedures.
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Affiliation(s)
- Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México. Apdo. postal 510-3, Cuernavaca 62250, Morelos, Mexico
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Oliveira GR, Silva MCM, Lucena WA, Nakasu EYT, Firmino AAP, Beneventi MA, Souza DSL, Gomes JE, de Souza JDA, Rigden DJ, Ramos HB, Soccol CR, Grossi-de-Sa MF. Improving Cry8Ka toxin activity towards the cotton boll weevil (Anthonomus grandis). BMC Biotechnol 2011; 11:85. [PMID: 21906288 PMCID: PMC3179717 DOI: 10.1186/1472-6750-11-85] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/09/2011] [Indexed: 11/13/2022] Open
Abstract
Background The cotton boll weevil (Anthonomus grandis) is a serious insect-pest in the Americas, particularly in Brazil. The use of chemical or biological insect control is not effective against the cotton boll weevil because of its endophytic life style. Therefore, the use of biotechnological tools to produce insect-resistant transgenic plants represents an important strategy to reduce the damage to cotton plants caused by the boll weevil. The present study focuses on the identification of novel molecules that show improved toxicity against the cotton boll weevil. In vitro directed molecular evolution through DNA shuffling and phage display screening was applied to enhance the insecticidal activity of variants of the Cry8Ka1 protein of Bacillus thuringiensis. Results Bioassays carried out with A. grandis larvae revealed that the LC50 of the screened mutant Cry8Ka5 toxin was 3.15-fold higher than the wild-type Cry8Ka1 toxin. Homology modelling of Cry8Ka1 and the Cry8Ka5 mutant suggested that both proteins retained the typical three-domain Cry family structure. The mutated residues were located mostly in loops and appeared unlikely to interfere with molecular stability. Conclusions The improved toxicity of the Cry8Ka5 mutant obtained in this study will allow the generation of a transgenic cotton event with improved potential to control A. grandis.
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Affiliation(s)
- Gustavo R Oliveira
- Embrapa Recursos Genéticos e Biotecnologia, PqEB- Final W5 Norte -Brasília, DF, Brasil
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Silva-Werneck J, Ellar D. Characterization of a novel Cry9Bb δ-endotoxin from Bacillus thuringiensis. J Invertebr Pathol 2008; 98:320-8. [DOI: 10.1016/j.jip.2008.03.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2007] [Revised: 02/14/2008] [Accepted: 03/24/2008] [Indexed: 10/22/2022]
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Investigating the properties of Bacillus thuringiensis Cry proteins with novel loop replacements created using combinatorial molecular biology. Appl Environ Microbiol 2008; 74:3497-511. [PMID: 18408065 DOI: 10.1128/aem.02844-07] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Cry proteins are a large family of crystalline toxins produced by Bacillus thuringiensis. Individually, the family members are highly specific, but collectively, they target a diverse range of insects and nematodes. Domain II of the toxins is important for target specificity, and three loops at its apex have been studied extensively. There is considerable interest in determining whether modifications in this region may lead to toxins with novel specificity or potency. In this work, we studied the effect of loop substitution on toxin stability and specificity. For this purpose, sequences derived from antibody complementarity-determining regions (CDR) were used to replace native domain II apical loops to create "Crybodies." Each apical loop was substituted either individually or in combination with a library of third heavy-chain CDR (CDR-H3) sequences to create seven distinct Crybody types. An analysis of variants from each library indicated that the Cry1Aa framework can tolerate considerable sequence diversity at all loop positions but that some sequence combinations negatively affect structural stability and protease sensitivity. CDR-H3 substitution showed that loop position was an important determinant of insect toxicity: loop 2 was essential for activity, whereas the effects of substitutions at loop 1 and loop 3 were sequence dependent. Unexpectedly, differences in toxicity did not correlate with binding to cadherins--a major class of toxin receptors--since all Crybodies retained binding specificity. Collectively, these results serve to better define the role of the domain II apical loops as determinants of specificity and establish guidelines for their modification.
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Fernández LE, Gómez I, Pacheco S, Arenas I, Gill SS, Bravo A, Soberón M. Employing phage display to study the mode of action of Bacillus thuringiensis Cry toxins. Peptides 2008; 29:324-9. [PMID: 18226423 PMCID: PMC2267870 DOI: 10.1016/j.peptides.2007.07.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 07/10/2007] [Indexed: 11/18/2022]
Abstract
Phage display is an in vitro method for selecting polypeptides with desired properties from a large collection of variants. The insecticidal Cry toxins produced by Bacillus thuringiensis are highly specific to different insects. Various proteins such as cadherin, aminopeptidase-N (APN) and alkaline phosphatase (ALP) have been characterized as potential Cry-receptors. We used phage display to characterize the Cry toxin-receptor interaction(s). By employing phage-libraries that display single-chain antibodies (scFv) from humans or from immunized rabbits with Cry1Ab toxin or random 12-residues peptides, we have identified the epitopes that mediate binding of lepidopteran Cry1Ab toxin with cadherin and APN receptors from Manduca sexta and the interaction of dipteran Cry11Aa toxin with the ALP receptor from Aedes aegypti. Finally we displayed in phages the Cry1Ac toxin and discuss the potential for selecting Cry variants with improved toxicity or different specificity.
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Affiliation(s)
- Luisa Elena Fernández
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Isabel Gómez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Sabino Pacheco
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Iván Arenas
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Sarjeet S. Gill
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico
| | - Mario Soberón
- *Corresponding author: Phone 52 777 3291618, Fax 52 777 3291624
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18
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Pinheiro VB, Ellar DJ. Expression and insecticidal activity of Yersinia pseudotuberculosis and Photorhabdus luminescens toxin complex proteins. Cell Microbiol 2007; 9:2372-80. [PMID: 17573906 DOI: 10.1111/j.1462-5822.2007.00966.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photorhabdus luminescens toxin complex (Tc) has been characterized as a potent three-component insecticidal protein complex. Homologues of genes encoding P. luminescens Tc components have been identified in several other enterobacteria and in Gram-positive bacteria, showing these genes are widespread in bacteria. In particular, tc gene homologues have been identified in Yersinia enterocolitica, Yersinia pseudotuberculosis and Yersinia pestis and may have a role in Y. pestis evolution. Y. enterocolitica tc genes have been shown to be active against Manduca sexta larvae. Here, we demonstrate that expression optimization is essential to obtain bioactive P. luminescens Tc proteins and demonstrate that TcaAB and TcdB + TccC are stand-alone toxins against a M. sexta insect model. Moreover, we report that Y. pseudotuberculosis IP32953 Tc proteins are also toxic to M. sexta larvae but do not cross-potentiate as P. luminescens Tc components.
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Affiliation(s)
- Vitor B Pinheiro
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
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19
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Ishikawa H, Hoshino Y, Motoki Y, Kawahara T, Kitajima M, Kitami M, Watanabe A, Bravo A, Soberon M, Honda A, Yaoi K, Sato R. A system for the directed evolution of the insecticidal protein from Bacillus thuringiensis. Mol Biotechnol 2007; 36:90-101. [PMID: 17914188 DOI: 10.1007/s12033-007-0001-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Revised: 11/30/1999] [Accepted: 09/13/2006] [Indexed: 11/28/2022]
Abstract
Theoretically, the activity of AB-type toxin molecules such as the insecticidal toxin (Cry toxin) from B. thuringiensis, which have one active site and two binding site, is improved in parallel with the binding affinity to its receptor. In this experiment, we tried to devise a method for the directed evolution of Cry toxins to increase the binding affinity to the insect receptor. Using a commercial T7 phage-display system, we expressed Cry1Aa toxin on the phage surface as fusions with the capsid protein 10B. These recombinant phages bound to a cadherin-like protein that is one of the Cry1Aa toxin receptors in the model target insect Bombyx mori. The apparent affinity of Cry1Aa-expressing phage for the receptor was higher than that of Cry1Ab-expressing phage. Phages expressing Cry1Aa were isolated from a mixed suspension of phages expressing Cry1Ab and concentrated by up to 130,000-fold. Finally, random mutations were made in amino acid residues 369-375 in domain 2 of Cry1Aa toxin, the mutant toxins were expressed on phages, and the resulting phage library was screened with cadherin-like protein-coated beads. As a result, phages expressing abnormal or low-affinity mutant toxins were excluded, and phages with high-affinity mutant toxins were selected. These results indicate that a method combining T7 phage display with selection using cadherin-like protein-coated magnetic beads can be used to increase the activity of easily obtained, low-activity Cry toxins from bacteria.
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Affiliation(s)
- Hiroshi Ishikawa
- Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
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20
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Yang Y, Wang L, Gaviria A, Yuan Z, Berry C. Proteolytic stability of insecticidal toxins expressed in recombinant bacilli. Appl Environ Microbiol 2006; 73:218-25. [PMID: 17098916 PMCID: PMC1797119 DOI: 10.1128/aem.01100-06] [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: 11/20/2022] Open
Abstract
The production of the vegetative mosquitocidal toxin Mtx1 from Bacillus sphaericus was redirected to the sporulation phase by replacement of its weak, native promoter with the strong sporulation promoter of the bin genes. Recombinant bacilli developed toxicity during early sporulation, but this declined rapidly in later stages, indicating the proteolytic instability of the toxin. Inhibition studies indicated the action of a serine proteinase, and similar degradation was also seen with the purified B. sphaericus enzyme sphericase. Following the identification of the initial cleavage site involved in this degradation, mutant Mtx1 proteins were expressed in an attempt to overcome destructive cleavage while remaining capable of proteolytic activation. However, the apparently broad specificity of sphericase seems to make this impossible. The stability of a further vegetative toxin, Mtx2, was also found to be low when it was exposed to sphericase or conditioned medium. Random mutation of the receptor binding loops of the Bacillus thuringiensis Cry1Aa toxin did, in contrast, allow production of significant levels of spore-associated protein in the form of parasporal crystals. The exploitation of vegetative toxins may, therefore, be greatly limited by their susceptibility to proteinases produced by the host bacteria, whereas the sequestration of sporulation-associated toxins into crystals may make them more amenable to use in strain improvement.
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Affiliation(s)
- Yankun Yang
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff CF10 3US, United Kingdom
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Nathan S, Aziz DHA, Mahadi NM. Phage displayed Bacillus thuringiensis Cry1Ba4 toxin is toxic to Plutella xylostella. Curr Microbiol 2006; 53:412-5. [PMID: 17036210 DOI: 10.1007/s00284-006-0164-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 07/10/2006] [Indexed: 10/24/2022]
Abstract
We constructed recombinant phage particles displaying the Bacillus thuringiensis Cry1Ba4 active toxin using the pfUSE5 and pComb3X phagemid vectors. The recombinant phage particles were screened and evaluated for displayed biologically active Cry1Ba4 toxin against the target insect larvae. Concurrent expression of Cry1Ba4 protoxin was carried out using the pETBlue -2 plasmid expression vector in Escherichia coli Tuner (DE3)pLacI and the protoxin was successfully expressed at a size of 129 kDa. In the bioassay, 3.30 mg crude extract of Cry1Ba4 protoxin, 9.35 x 10(9) TU and 7.70 x 10(9) TU of induced recombinant phage particles carrying Cry1Ba4 active toxin displayed on pComb3X and pFUSE5, respectively, demonstrated mortality of greater than 85% against Plutella xylostella (third-instar) within 48 hours. Thus, we have successfully displayed the Cry1Ba4 activated toxin on the surface of a phage and demonstrated toxicity towards larvae.
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Affiliation(s)
- Sheila Nathan
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Selangor, Malaysia.
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Pacheco S, Gómez I, Sato R, Bravo A, Soberón M. Functional display of Bacillus thuringiensis Cry1Ac toxin on T7 phage. J Invertebr Pathol 2006; 92:45-9. [PMID: 16603180 DOI: 10.1016/j.jip.2006.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2005] [Revised: 01/25/2006] [Accepted: 02/17/2006] [Indexed: 11/24/2022]
Abstract
The Cry1Ac toxin from Bacillus thuringiensis was displayed on the surface of T7 phage. The cry1Ac gene was fused to the C-terminal end of T7-10B capsid protein and displayed on the surface of T7 phage as revealed by Western blot analysis of the purified phage particles. The T7-Cry1Ac phages retained toxicity against Manduca sexta larvae. We demonstrated that the T7-Cry1Ac phage interacts with Cry1Ac receptors present in M. sexta BBMV either in solution or in overlay binding assays.
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Affiliation(s)
- Sabino Pacheco
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos
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