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Meng M, Shen C, Lin M, Jin J, Chen W, Zhang X, Xu C, Hu X, Zhu Q, Chen C, Xie Y, Jacob Pooe O, Crickmore N, Liu X, Lü P, Liu Y. Characterization of the individual domains of the Bacillus thuringiensis Cry2Aa implicates Domain I as a possible binding site to Helicoverpa armigera. J Invertebr Pathol 2024; 205:108129. [PMID: 38754546 DOI: 10.1016/j.jip.2024.108129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024]
Abstract
Bacillus thuringiensis (Bt) Cry2Aa is a member of the Cry pore-forming, 3-domain, toxin family with activity against both lepidopteran and dipteran insects. Although domains II and III of the Cry toxins are believed to represent the primary specificity determinant through specific binding to cell receptors, it has been proposed that the pore-forming domain I of Cry2Aa also has such a role. Thus, a greater understanding of the functions of Cry2Aa's different domains could potentially be helpful in the rational design of improved toxins. In this work, cry2Aa and its domain fragments (DI, DII, DIII, DI-II and DII-DIII) were subcloned into the vector pGEX-6P-1 and expressed in Escherichia coli. Each protein was recognized by anti-Cry2Aa antibodies and, except for the DII fragment, could block binding of the antibody to Cry2Aa. Cry2Aa and its DI and DI-II fragments bound to brush border membrane vesicles (BBMV) from H. armigera and also to a ca 150 kDa BBMV protein on a far western (ligand) blot. In contrast the DII, DIII and DII-III fragments bound to neither of these. None of the fragments were stable in H. armigera gut juice nor showed any toxicity towards this insect. Our results indicate that contrary to the general model of Cry toxin activity domain I plays a role in the binding of the toxin to the insect midgut.
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Affiliation(s)
- Meng Meng
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Cheng Shen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Manman Lin
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Jiafeng Jin
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Wei Chen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Xiao Zhang
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Chongxin Xu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Xiaodan Hu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Qing Zhu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Chengyu Chen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Yajing Xie
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Ofentse Jacob Pooe
- School of Life Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Neil Crickmore
- School of Biological Sciences, University of Sussex, Brighton BN1 9RH, United Kingdom
| | - Xianjin Liu
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Peng Lü
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China.
| | - Yuan Liu
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China.
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Zhang Q, Hua G, Adang MJ. Effects and mechanisms of Bacillus thuringiensis crystal toxins for mosquito larvae. INSECT SCIENCE 2017; 24:714-729. [PMID: 27628909 DOI: 10.1111/1744-7917.12401] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 08/15/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
Bacillus thuringiensis is a Gram-positive aerobic bacterium that produces insecticidal crystalline inclusions during sporulation phases of the mother cell. The virulence factor, known as parasporal crystals, is composed of Cry and Cyt toxins. Most Cry toxins display a common 3-domain topology. Cry toxins exert intoxication through toxin activation, receptor binding and pore formation in a suitable larval gut environment. The mosquitocidal toxins of Bt subsp. israelensis (Bti) were found to be highly active against mosquito larvae and are widely used for vector control. Bt subsp. jegathesan is another strain which possesses high potency against broad range of mosquito larvae. The present review summarizes characterized receptors for Cry toxins in mosquito larvae, and will also discuss the diversity and effects of 3-D mosquitocidal Cry toxin and the ongoing research for Cry toxin mechanisms generated from investigations of lepidopteran and dipteran larvae.
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Affiliation(s)
- Qi Zhang
- College of Plant Protection, Shenyang Agricultural University, Shenyang, China
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Gang Hua
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Michael J Adang
- Department of Entomology, University of Georgia, Athens, GA, USA
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA, USA
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3
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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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Variant Cry1Ia toxins generated by DNA shuffling are active against sugarcane giant borer. J Biotechnol 2009; 145:215-21. [PMID: 19931577 DOI: 10.1016/j.jbiotec.2009.11.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 11/03/2009] [Accepted: 11/12/2009] [Indexed: 11/22/2022]
Abstract
Sugarcane giant borer (Telchin licus licus) is a serious sugarcane pest in Americas whose endophytic lifestyle hampers effective chemical and biological controls. Therefore, development of alternative control methods is extremely important. Envisaging development of transgenic plants resistant to this pest, we investigated the effect of the Bacillus thuringiensis Cry protein Cry1Ia12synth (truncated protein lacking C-terminus with plant codon usage) and variants against T. l. licus. cry1Ia12synth gene was used to generate mutated variants, which were screened for toxicity toward T. l. licus. For that purpose, an innovative technique combining cry gene shuffling with phage-display was used to build a combinatorial library comprising 1.97x10(5) Cry1Ia12synth variants. Screening of this library for variants binding to T. l. licus Brush Border Midgut Vesicles led to the identification of hundreds of clones, out of which 30 were randomly chosen for toxicity testing. Bioassays revealed four variants exhibiting activity against T. l. licus as compared to the non-toxic Cry1Ia12synth. Eight single substitutions sites were found in these active variants. Based on theoretical molecular modelling, the probable implications of these mutations are discussed. Therefore, we have four genes encoding Cry1Ia12synth variants active against T. l. licus promising for future development of resistant transgenic sugarcane lines.
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Moonsom S, Chaisri U, Kasinrerk W, Angsuthanasombat C. Binding characteristics to mosquito-larval midgut proteins of the cloned domain II-III fragment from the Bacillus thuringiensis Cry4Ba toxin. BMB Rep 2008; 40:783-90. [PMID: 17927913 DOI: 10.5483/bmbrep.2007.40.5.783] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Receptor binding plays an important role in determining host specificity of the Bacillus thuringiensis Cry delta-endotoxins. Mutations in domains II and III have suggested the participation of certain residues in receptor recognition and insect specificity. In the present study, we expressed the cloned domain II-III fragment of Cry4Ba and examined its binding characteristics to mosquito-larval midgut proteins. The 43-kDa Cry4Ba-domain II-III protein over-expressed in Escherichia coli as inclusion bodies was only soluble when carbonate buffer, pH 10.0 was supplemented with 4 M urea. After renaturation via stepwise dialysis and subsequent purification, the refolded domain II-III protein, which specifically reacts with anti Cry4Ba-domain III monoclonal antibody, predominantly exists as a beta-sheet structure determined by circular dichroism spectroscopy. In vitro binding analysis to both histological midgut tissue sections and brush border membrane proteins prepared from susceptible Aedes aegypti mosquito-larvae revealed that the isolated Cry4Ba-domain II-III protein showed binding functionality comparable to the 65-kDa full-length active toxin. Altogether, the data present the 43-kDa Cry4Ba fragment comprising domains II and III that was produced in isolation was able to retain its receptor-binding characteristics to the target larval midgut proteins.
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Affiliation(s)
- Seangdeun Moonsom
- Laboratory of Molecular Biophysics and Structural Biochemistry, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
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Chayaratanasin P, Moonsom S, Sakdee S, Chaisri U, Katzenmeier G, Angsuthanasombat C. High level of soluble expression in Escherichia coli and characterisation of the cloned Bacillus thuringiensis Cry4Ba domain III fragment. BMB Rep 2007; 40:58-64. [PMID: 17244483 DOI: 10.5483/bmbrep.2007.40.1.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Similar to the other known structures of Bacillus thuringiensis Cry delta-endotoxins, the crystal structure of the 65-kDa activated Cry4Ba toxin comprises three domains which are, from the N- to C-terminus, a bundle of alpha-helices, a three-beta-sheet domain, and a beta-sandwich. To investigate the properties of the C-terminal domain III in isolation from the rest of the toxin, the cloned Cry4Ba-domain III was over-expressed as a 21-kDa soluble protein in Escherichia coli, which cross-reacted with anti-Cry4Ba domain III monoclonal antibody. A highly-purified domain III was obtained in a monomeric form by ion-exchange and size-exclusion FPLC. Circular dichroism spectroscopy indicated that the isolated domain III fragment distinctly exists as a beta-sheet structure, corresponding to the domain III structure embodied in the Cry4Ba crystal structure. In vitro binding analysis via immuno-histochemical assay revealed that the Cry4Ba-domain III protein was able to bind to the apical microvilli of the susceptible Stegomyia aegypti larval midguts, albeit at lower-binding activity when compared with the full-length active toxin. These results demonstrate for the first time that the C-terminal domain III of the Cry4Ba mosquito-larvicidal protein, which can be isolated as a native folded monomer, conceivably participates in toxin-receptor recognition.
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Affiliation(s)
- Poramed Chayaratanasin
- Laboratory of Molecular Biophysics and Structural Biochemistry, Institute of Molecular Biology and Genetics, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
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Leetachewa S, Katzenmeier G, Angsuthanasombat C. Novel preparation and characterization of the alpha4-loop-alpha5 membrane-perturbing peptide from the Bacillus thuringiensis Cry4Ba delta-endotoxin. BMB Rep 2006; 39:270-7. [PMID: 16756755 DOI: 10.5483/bmbrep.2006.39.3.270] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Helices 4 and 5 of the Bacillus thuringiensis Cry4Ba delta-endotoxin have been shown to be important determinants for mosquito-larvicidal activity, likely being involved in membrane-pore formation. In this study, the Cry4Ba mutant protein containing an additional engineered tryptic cleavage site was used to produce the alpha4-alpha5 hairpin peptide by an efficient alternative strategy. Upon solubilization of toxin inclusions expressed in Escherichia coli and subsequent digestion with trypsin, the 130-kDa mutant protoxin was processed to protease-resistant fragments of ca. 47, 10 and 7 kDa. The 7-kDa fragment was identified as the alpha4-loop-alpha5 hairpin via N-terminal sequencing and mass spectrometry, and was successfully purified by size-exclusion FPLC and reversed-phase HPLC. Using circular dichroism spectroscopy, the 7-kDa peptide was found to exist predominantly as an alpha-helical structure. Membrane perturbation studies by using fluorimetric calcein-release assays revealed that the 7-kDa helical hairpin is highly active against unilamellar liposomes compared with the 65-kDa activated full-length toxin. These results directly support the role of the alpha4-loop-alpha5 hairpin in membrane perturbation and pore formation of the full-length Cry4Ba toxin.
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Affiliation(s)
- Somphob Leetachewa
- Laboratory of Molecular Biophysics and Structural Biochemistry, Institute of Molecular Biology and Genetics, Mahidol University, Nakornpathom, Thailand
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8
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Molecular approaches for identification and construction of novel insecticidal genes for crop protection. World J Microbiol Biotechnol 2005. [DOI: 10.1007/s11274-005-9027-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Avisar D, Keller M, Gazit E, Prudovsky E, Sneh B, Zilberstein A. The Role of Bacillus thuringiensis Cry1C and Cry1E Separate Structural Domains in the Interaction with Spodoptera littoralis Gut Epithelial Cells. J Biol Chem 2004; 279:15779-86. [PMID: 14963036 DOI: 10.1074/jbc.m312597200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Bacillus thuringiensis delta-endotoxins Cry1C and Cry1E share toxicity against several important lepidopteran species. Their combined use to delay development of resistance in target insects depends on their differential interaction with the gut epithelial cells. The three structural domains and combinations of two consecutive domains of Cry1C and Cry1E were separately expressed in Escherichia coli, and their interactions with the brush border membrane vesicles (BBMV) of Cry1E-tolerant and -susceptible Spodoptera littoralis larvae were studied. About 80% reduction in binding of Cry1E and each of its separate domains to BBMV of Cry1E-tolerant larvae was observed, whereas Cry1C was toxic to all larvae and bound equally to BBMV derived from both Cry1E-tolerant and -susceptible larvae. These results suggest differential interactions of the two toxins with BBMV encompassing all three domains. Comparable binding assays performed with fluorescent Cry1C and Cry1C domain II showed that Cry1C has higher Bmax and lower Kd than Cry1C domain II and further supported the existence of toxin multisite interactions. Competitive binding assays were used to estimate the sequence of interaction events. Cry1C domain II could compete with domain III binding, whereas domain III did not interfere with domain II binding, indicating sequential interactions of domain III and then domain II with the same membrane site. No competition between domain II of Cry1C and Cry1E was observed, confirming the existence of different domain II binding sites for the two toxins. Taken together, all three domains specifically interact with the epithelial cell membrane. The folding of the three-domain toxin probably dictates the sequence of interaction events.
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Affiliation(s)
- Dror Avisar
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
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Gómez I, Oltean DI, Gill SS, Bravo A, Soberón M. Mapping the epitope in cadherin-like receptors involved in Bacillus thuringiensis Cry1A toxin interaction using phage display. J Biol Chem 2001; 276:28906-12. [PMID: 11384982 DOI: 10.1074/jbc.m103007200] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In susceptible lepidopteran insects, aminopeptidase N and cadherin-like proteins are the putative receptors for Bacillus thuringiensis (Bt) toxins. Using phage display, we identified a key epitope that is involved in toxin-receptor interaction. Three different scFv molecules that bind Cry1Ab toxin were obtained, and these scFv proteins have different amino acid sequences in the complementary determinant region 3 (CDR3). Binding analysis of these scFv molecules to different members of the Cry1A toxin family and to Escherichia coli clones expressing different Cry1A toxin domains showed that the three selected scFv molecules recognized only domain II. Heterologous binding competition of Cry1Ab toxin to midgut membrane vesicles from susceptible Manduca sexta larvae using the selected scFv molecules showed that scFv73 competed with Cry1Ab binding to the receptor. The calculated binding affinities (K(d)) of scFv73 to Cry1Aa, Cry1Ab, and Cry1Ac toxins are in the range of 20-51 nm. Sequence analysis showed this scFv73 molecule has a CDR3 significantly homologous to a region present in the cadherin-like protein from M. sexta (Bt-R(1)), Bombyx mori (Bt-R(175)), and Lymantria dispar. We demonstrated that peptides of 8 amino acids corresponding to the CDR3 from scFv73 or to the corresponding regions of Bt-R(1) or Bt-R(175) are also able to compete with the binding of Cry1Ab and Cry1Aa toxins to the Bt-R(1) or Bt-R(175) receptors. Finally, we showed that synthetic peptides homologous to Bt-R(1) and scFv73 CDR3 and the scFv73 antibody decreased the in vivo toxicity of Cry1Ab to M. sexta larvae. These results show that we have identified the amino acid region of Bt-R(1) and Bt-R(175) involved in Cry1A toxin interaction.
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Affiliation(s)
- I Gómez
- Instituto de Biotecnologia, Departamento de Microbiologia Molecular, Universidad Nacional Autónoma de México, Apdo postal 510-3, Cuernavaca, Morelos 62250, México
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Schnepf E, Crickmore N, Van Rie J, Lereclus D, Baum J, Feitelson J, Zeigler DR, Dean DH. Bacillus thuringiensis and its pesticidal crystal proteins. Microbiol Mol Biol Rev 1998; 62:775-806. [PMID: 9729609 PMCID: PMC98934 DOI: 10.1128/mmbr.62.3.775-806.1998] [Citation(s) in RCA: 1685] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism's pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.
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Affiliation(s)
- E Schnepf
- Mycogen Corp., San Diego, California 92121, USA
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