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Shwe SM, Prabu S, Jing D, He K, Wang Z. Synergistic interaction of Cry1Ah and Vip3Aa19 proteins combination with midgut ATP-binding cassette subfamily C receptors of Conogethes punctiferalis (Guenée) (Lepidoptera: Crambidae). Int J Biol Macromol 2022; 213:871-879. [PMID: 35690160 DOI: 10.1016/j.ijbiomac.2022.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 06/01/2022] [Accepted: 06/05/2022] [Indexed: 11/30/2022]
Abstract
Bacillus thuringiensis Cry and Vip proteins are highly effective at controlling agricultural pests and could be used in pyramided transgenic crops. However, the molecular mechanism underlying the Cry1Ah and Vip3Aa19 synergistic interaction has never been investigated at the molecular level in Yellow peach moth (YPM) Conogethes punctiferalis. Binding affinity and synergism of Cry1Ah and Vip3Aa19 proteins with ABC transporter subfamily C receptors ABCC1, ABCC2 and ABCC3 proteins from the midgut of YPM larva by using surface plasmon resonance (SPR) and pull-down assays. Both assays revealed that Cry1Ah could interact with ABCC1, ABCC2, and ABCC3, whereas Vip3Aa19 only interacts with ABCC1 and ABCC3, but not with ABCC2. Hence, when compared to the Vip3Aa19 protein, Cry1Ah had a higher binding affinity for ABCC1, ABCC2, and ABCC3. Furthermore, competitive binding assay between Cry1Ah and Vip3Aa19 protein with ABC transporter subfamily C receptors resulted in the final eluted protein samples displaying vibrant blue bands of Cry1Ah and very faint bands of Vip3Aa19. Suggesting that Cry and Vip proteins could deliver a synergistic effect after cleaving the midgut proteases. Therefore, this finding indicated that the Cry1Ah and Vip3Aa19 do not compete for interacting with midgut receptors and thus provide strong synergism against YPM.
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Affiliation(s)
- Su Mon Shwe
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Sivaprasath Prabu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Dapeng Jing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China
| | - Zhenying Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China.
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Lázaro-Berenguer M, Quan Y, Hernández-Martínez P, Ferré J. In vivo competition assays between Vip3 proteins confirm the occurrence of shared binding sites in Spodoptera littoralis. Sci Rep 2022; 12:4578. [PMID: 35301405 PMCID: PMC8931066 DOI: 10.1038/s41598-022-08633-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/07/2022] [Indexed: 11/09/2022] Open
Abstract
Due to their different specificity, the use of Vip3 proteins from Bacillus thuringiensis in combination with the conventionally used Cry proteins in crop protection is being essential to counteract the appearance of insect resistance. Therefore, understanding the mode of action of Vip3 proteins is crucial for their better application, with special interest on the binding to membrane receptors as the main step for specificity. Derived from in vitro heterologous competition binding assays using 125I-Vip3A and other Vip3 proteins as competitors, it has been shown that Vip3 proteins share receptors in Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). In this study, using 125I-Vip3Aa, we have first extended the in vitro competition binding site model of Vip3 proteins to Spodoptera littoralis. With the aim to understand the relevance (in terms of toxicity) of the binding to the midgut sites observed in vitro on the insecticidal activity of these proteins, we have performed in vivo competition assays with S. littoralis larvae, using disabled mutant (non-toxic) Vip3 proteins as competitors for blocking the toxicity of Vip3Aa and Vip3Af. The results of the in vivo competition assays confirm the occurrence of shared binding sites among Vip3 proteins and help understand the functional role of the shared binding sites as revealed in vitro.
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Affiliation(s)
- María Lázaro-Berenguer
- Institute of Biotechnology and Biomedicine (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain
| | - Yudong Quan
- Institute of Biotechnology and Biomedicine (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain
| | - Patricia Hernández-Martínez
- Institute of Biotechnology and Biomedicine (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain
| | - Juan Ferré
- Institute of Biotechnology and Biomedicine (BIOTECMED), Department of Genetics, Universitat de València, 46100, Burjassot, Spain.
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3
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Critical domains in the specific binding of radiolabelled Vip3Af insecticidal protein to brush border membrane vesicles from Spodoptera spp. and cultured insect cells. Appl Environ Microbiol 2021; 87:e0178721. [PMID: 34586902 DOI: 10.1128/aem.01787-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis have been used, in combination with Cry proteins, to better control insect pests and as a strategy to delay the evolution of resistance to Cry proteins in Bt crops (crops protected from insect attack by the expression of proteins from B. thuringiensis). In this study, we have set up the conditions to analyze the specific binding of 125I-Vip3Af to Spodoptera frugiperda and Spodoptera exigua brush border membrane vesicles (BBMV). Heterologous competition binding experiments revealed that Vip3Aa shares the same binding sites with Vip3Af, but that Vip3Ca does not recognize all of them. As expected, Cry1Ac and Cry1F did not compete for Vip3Af binding sites. By trypsin treatment of selected alanine-mutants, we were able to generate truncated versions of Vip3Af. Their use as competitors with 125I-Vip3Af indicated that only those molecules containing domains I to III (DI-III and DI-IV) were able to compete with the trypsin-activated Vip3Af protein for binding, and that molecules only containing either domain IV or domains IV and V (DIV and DIV-V) were unable to compete with Vip3Af. These results were further confirmed with competition binding experiments using 125I-DI-III. In addition, the truncated protein 125I-DI-III also bound specifically to Sf21 cells. Cell viability assays showed that the truncated proteins DI-III and DI-IV were as toxic to Sf21 cells as the activated Vip3Af, suggesting that domains IV and V are not necessary for the toxicity to Sf21 cells, in contrast to their requirement in vivo. IMPORTANCE This study shows that Vip3Af binding sites are fully shared with Vip3Aa, only partially shared with Vip3Ca, and not shared with Cry1Ac and Cry1F in two Spodoptera spp. Truncated versions of Vip3Af revealed that only domains I to III were necessary for the specific binding, most likely because they can form the functional tetrameric oligomer and because domain III is supposed to contain the binding epitopes. In contrast to results obtained in vivo (bioassays against larvae), domains IV and V are not necessary for the ex vivo toxicity to Sf21 cells.
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Quan Y, Yang J, Wang Y, Hernández-Martínez P, Ferré J, He K. The Rapid Evolution of Resistance to Vip3Aa Insecticidal Protein in Mythimna separata (Walker) Is Not Related to Altered Binding to Midgut Receptors. Toxins (Basel) 2021; 13:toxins13050364. [PMID: 34065247 PMCID: PMC8190635 DOI: 10.3390/toxins13050364] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/13/2021] [Accepted: 05/17/2021] [Indexed: 12/22/2022] Open
Abstract
Laboratory selection for resistance of field populations is a well-known and useful tool to understand the potential of insect populations to evolve resistance to insecticides. It provides us with estimates of the frequency of resistance alleles and allows us to study the mechanisms by which insects developed resistance to shed light on the mode of action and optimize resistance management strategies. Here, a field population of Mythimna separata was subjected to laboratory selection with either Vip3Aa, Cry1Ab, or Cry1F insecticidal proteins from Bacillus thuringiensis. The population rapidly evolved resistance to Vip3Aa reaching, after eight generations, a level of >3061-fold resistance, compared with the unselected insects. In contrast, the same population did not respond to selection with Cry1Ab or Cry1F. The Vip3Aa resistant population did not show cross resistance to either Cry1Ab or Cry1F. Radiolabeled Vip3Aa was tested for binding to brush border membrane vesicles from larvae from the susceptible and resistant insects. The results did not show any qualitative or quantitative difference between both insect samples. Our data, along with previous results obtained with other Vip3Aa-resistant populations from other insect species, suggest that altered binding to midgut membrane receptors is not the main mechanism of resistance to Vip3Aa.
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Affiliation(s)
- Yudong Quan
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain; (Y.Q.); (P.H.-M.)
| | - Jing Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China; (J.Y.); (Y.W.)
| | - Yueqin Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China; (J.Y.); (Y.W.)
| | - Patricia Hernández-Martínez
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain; (Y.Q.); (P.H.-M.)
| | - Juan Ferré
- Instituto de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100 Burjassot, Spain; (Y.Q.); (P.H.-M.)
- Correspondence: (J.F.); (K.H.)
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, No. 2, West Yuanmingyuan Road, Beijing 100193, China; (J.Y.); (Y.W.)
- Correspondence: (J.F.); (K.H.)
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Jurat-Fuentes JL, Heckel DG, Ferré J. Mechanisms of Resistance to Insecticidal Proteins from Bacillus thuringiensis. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:121-140. [PMID: 33417820 DOI: 10.1146/annurev-ento-052620-073348] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are used in sprayable formulations or produced in transgenic crops as the most successful alternatives to synthetic pesticides. The most relevant threat to sustainability of Bt insecticidal proteins (toxins) is the evolution of resistance in target pests. To date, high-level resistance to Bt sprays has been limited to one species in the field and another in commercial greenhouses. In contrast, there are currently seven lepidopteran and one coleopteran species that have evolved practical resistance to transgenic plants producing insecticidal Bt proteins. In this article, we present a review of the current knowledge on mechanisms of resistance to Bt toxins, with emphasis on key resistance genes and field-evolved resistance, to support improvement of Bt technology and its sustainability.
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Affiliation(s)
- Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee 37996, USA;
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany;
| | - Juan Ferré
- ERI of Biotechnology and Biomedicine (BIOTECMED), Universitat de València, Burjassot 46100, Spain;
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Current Insights on Vegetative Insecticidal Proteins (Vip) as Next Generation Pest Killers. Toxins (Basel) 2020; 12:toxins12080522. [PMID: 32823872 PMCID: PMC7472478 DOI: 10.3390/toxins12080522] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/09/2020] [Accepted: 08/11/2020] [Indexed: 02/01/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram negative soil bacterium. This bacterium secretes various proteins during different growth phases with an insecticidal potential against many economically important crop pests. One of the important families of Bt proteins is vegetative insecticidal proteins (Vip), which are secreted into the growth medium during vegetative growth. There are three subfamilies of Vip proteins. Vip1 and Vip2 heterodimer toxins have an insecticidal activity against many Coleopteran and Hemipteran pests. Vip3, the most extensively studied family of Vip toxins, is effective against Lepidopteron. Vip proteins do not share homology in sequence and binding sites with Cry proteins, but share similarities at some points in their mechanism of action. Vip3 proteins are expressed as pyramids alongside Cry proteins in crops like maize and cotton, so as to control resistant pests and delay the evolution of resistance. Biotechnological- and in silico-based analyses are promising for the generation of mutant Vip proteins with an enhanced insecticidal activity and broader spectrum of target insects.
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Núñez-Ramírez R, Huesa J, Bel Y, Ferré J, Casino P, Arias-Palomo E. Molecular architecture and activation of the insecticidal protein Vip3Aa from Bacillus thuringiensis. Nat Commun 2020; 11:3974. [PMID: 32769995 PMCID: PMC7414852 DOI: 10.1038/s41467-020-17758-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 07/08/2020] [Indexed: 12/27/2022] Open
Abstract
Bacillus thuringiensis Vip3 (Vegetative Insecticidal Protein 3) toxins are widely used in biotech crops to control Lepidopteran pests. These proteins are produced as inactive protoxins that need to be activated by midgut proteases to trigger cell death. However, little is known about their three-dimensional organization and activation mechanism at the molecular level. Here, we have determined the structures of the protoxin and the protease-activated state of Vip3Aa at 2.9 Å using cryo-electron microscopy. The reconstructions show that the protoxin assembles into a pyramid-shaped tetramer with the C-terminal domains exposed to the solvent and the N-terminal region folded into a spring-loaded apex that, after protease activation, drastically remodels into an extended needle by a mechanism akin to that of influenza haemagglutinin. These results provide the molecular basis for Vip3 activation and function, and serves as a strong foundation for the development of more efficient insecticidal proteins.
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Affiliation(s)
- Rafael Núñez-Ramírez
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain
| | - Juanjo Huesa
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
| | - Yolanda Bel
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
- Department of Genetics, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
| | - Juan Ferré
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
- Department of Genetics, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain
| | - Patricia Casino
- Departament de Bioquímica i Biologia Molecular, Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain.
- Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, Dr. Moliner 50, 46100, Burjassot, Spain.
- CIBER de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain.
| | - Ernesto Arias-Palomo
- Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain.
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Effect of substitutions of key residues on the stability and the insecticidal activity of Vip3Af from Bacillus thuringiensis. J Invertebr Pathol 2020; 186:107439. [PMID: 32663546 DOI: 10.1016/j.jip.2020.107439] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/16/2020] [Accepted: 07/05/2020] [Indexed: 11/21/2022]
Abstract
Modern agriculture demands for more sustainable agrochemicals to reduce the environmental and health impact. The whole process of the discovery and development of new active substances or control agents is sorely slow and expensive. Vegetative insecticidal proteins (Vip3) from Bacillus thuringiensis are specific toxins against caterpillars with a potential capacity to broaden the range of target pests. Site-directed mutagenesis is one of the most approaches used to test hypotheses on the role of different amino acids on the structure and function of proteins. To gain a better understanding of the role of key amino acid residues of Vip3A proteins, we have generated 12 mutants of the Vip3Af1 protein by site-directed mutagenesis, distributed along the five structural domains of the protein. Ten of these mutants were successfully expressed and tested for stability and toxicity against three insect pests (Spodoptera frugiperda, Spodoptera littoralis and Grapholita molesta). The results showed that, to render a wild type fragment pattern upon trypsin treatment, position 483 required an acidic residue, and position 552 an aromatic residue. Regarding toxicity, the change of Met34 to Lys34 significantly increased the toxicity of the protein for one of the three insect species tested (S. littoralis), whereas the other residue substitutions did not improve, or even decreased, insect toxicity, confirming their key role in the structure/function of the protein.
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The Cadherin Protein Is Not Involved in Susceptibility to Bacillus thuringiensis Cry1Ab or Cry1Fa Toxins in Spodoptera frugiperda. Toxins (Basel) 2020; 12:toxins12060375. [PMID: 32517191 PMCID: PMC7354596 DOI: 10.3390/toxins12060375] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/01/2020] [Accepted: 06/03/2020] [Indexed: 11/17/2022] Open
Abstract
It is well known that insect larval midgut cadherin protein serves as a receptor of Bacillus thuringiensis (Bt) crystal Cry1Ac or Cry1Ab toxins, since structural mutations and downregulation of cad gene expression are linked with resistance to Cry1Ac toxin in several lepidopteran insects. However, the role of Spodoptera frugiperda cadherin protein (SfCad) in the mode of action of Bt toxins remains elusive. Here, we investigated whether SfCad is involved in susceptibility to Cry1Ab or Cry1Fa toxins. In vivo, knockout of the SfCad gene by CRISPR/Cas 9 did not increase tolerance to either of these toxins in S. frugiperda larvae. In vitro cytotoxicity assays demonstrated that cultured insect TnHi5 cells expressing GFP-tagged SfCad did not increase susceptibility to activated Cry1Ab or Cry1Fa toxins. In contrast, expression of another well recognized Cry1A receptor in this cell line, the ABCC2 transporter, increased the toxicity of both Cry1Ab and Cry1Fa toxins, suggesting that SfABCC2 functions as a receptor of these toxins. Finally, we showed that the toxin-binding region of SfCad did not bind to activated Cry1Ab, Cry1Ac, nor Cry1Fa. All these results support that SfCad is not involved in the mode of action of Cry1Ab or Cry1Fa toxins in S. frugiperda.
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Tabashnik BE, Carrière Y. Evaluating Cross-resistance Between Vip and Cry Toxins of Bacillus thuringiensis. JOURNAL OF ECONOMIC ENTOMOLOGY 2020; 113:553-561. [PMID: 31821498 DOI: 10.1093/jee/toz308] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Indexed: 05/27/2023]
Abstract
Crops genetically engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have revolutionized control of some major pests. Some recently introduced Bt crops make Vip3Aa, a vegetative insecticidal protein (Vip), which reportedly does not share binding sites or structural homology with the crystalline (Cry) proteins of Bt used widely in transgenic crops for more than two decades. Field-evolved resistance to Bt crops with practical consequences for pest control includes 21 cases that collectively reduce the efficacy of nine Cry proteins, but such practical resistance has not been reported yet for any Vip. Here, we review previously published data to evaluate cross-resistance between Vip and Cry toxins. We analyzed 31 cases based on 48 observations, with each case based on one to five observations assessing cross-resistance from pairwise comparisons between 21 resistant strains and 13 related susceptible strains of eight species of lepidopteran pests. Confirming results from previous analyses of smaller data sets, we found weak, statistically significant cross-resistance between Vip3 and Cry1 toxins, with a mean of 1.5-fold cross-resistance in 21 cases (range: 0.30-4.6-fold). Conversely, we did not detect significant positive cross-resistance between Vip3 toxins and Cry2Ab. Distinguishing between weak, significant cross-resistance, and no cross-resistance may be useful for better understanding mechanisms of resistance and effectively managing pest resistance to Bt crops.
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Affiliation(s)
| | - Yves Carrière
- Department of Entomology, University of Arizona, Tucson, AZ
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Gomis-Cebolla J, Ferreira dos Santos R, Wang Y, Caballero J, Caballero P, He K, Jurat-Fuentes JL, Ferré J. Domain Shuffling between Vip3Aa and Vip3Ca: Chimera Stability and Insecticidal Activity against European, American, African, and Asian Pests. Toxins (Basel) 2020; 12:E99. [PMID: 32033215 PMCID: PMC7076965 DOI: 10.3390/toxins12020099] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 11/16/2022] Open
Abstract
The bacterium Bacillus thuringiensis produces insecticidal Vip3 proteins during the vegetative growth phase with activity against several lepidopteran pests. To date, three different Vip3 protein families have been identified based on sequence identity: Vip3A, Vip3B, and Vip3C. In this study, we report the construction of chimeras by exchanging domains between Vip3Aa and Vip3Ca, two proteins with marked specificity differences against lepidopteran pests. We found that some domain combinations made proteins insoluble or prone to degradation by trypsin as most abundant insect gut protease. The soluble and trypsin-stable chimeras, along with the parental proteins Vip3Aa and Vip3Ca, were tested against lepidopteran pests from different continents: Spodopteraexigua, Spodopteralittoralis, Spodopterafrugiperda,Helicoverpaarmigera, Mamestrabrassicae, Anticarsiagemmatalis, and Ostriniafurnacalis. The exchange of the Nt domain (188 N-terminal amino acids) had little effect on the stability and toxicity (equal or slightly lower) of the resulting chimeric protein against all insects except for S.frugiperda, for which the chimera with the Nt domain from Vip3Aa and the rest of the protein from Vip3Ca showed a significant increase in toxicity compared to the parental Vip3Ca. Chimeras with the C-terminal domain from Vip3Aa (from amino acid 510 of Vip3Aa to the Ct) with the central domain of Vip3Ca (amino acids 189-509 based on the Vip3Aa sequence) made proteins that could not be solubilized. Finally, the chimera including the Ct domain of Vip3Ca and the Nt and central domain from Vip3Aa was unstable. Importantly, an insect species tolerant to Vip3Aa but susceptible to Vip3Ca, such as Ostriniafurnacalis, was also susceptible to chimeras maintaining the Ct domain from Vip3Ca, in agreement with the hypothesis that the Ct region of the protein is the one conferring specificity to Vip3 proteins.
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Affiliation(s)
- Joaquín Gomis-Cebolla
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100-Burjassot, Spain;
| | - Rafael Ferreira dos Santos
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (R.F.d.S.); (J.L.J.-F.)
| | - Yueqin Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Y.W.); (K.H.)
| | - Javier Caballero
- Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, Campus Arrosadía, 31192 Mutilva, Navarra, Spain; (J.C.); (P.C.)
| | - Primitivo Caballero
- Institute for Multidisciplinary Applied Biology, Universidad Pública de Navarra, Campus Arrosadía, 31192 Mutilva, Navarra, Spain; (J.C.); (P.C.)
| | - Kanglai He
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; (Y.W.); (K.H.)
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, USA; (R.F.d.S.); (J.L.J.-F.)
| | - Juan Ferré
- ERI de Biotecnología y Biomedicina (BIOTECMED), Department of Genetics, Universitat de València, 46100-Burjassot, Spain;
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