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Guo Q, Li W, Niu Y, Dai X, Chen L. Culex quinquefasciatus membrane-bound alkaline phosphatase is a putative receptor for Lysinibacillus sphaericus Tpp49Aa1 toxin. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2024; 164:104044. [PMID: 38036275 DOI: 10.1016/j.ibmb.2023.104044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/02/2023]
Abstract
The binary toxin Cry48Aa1/Tpp49Aa1 produced by Lysinibacillus sphaericus exhibits potent toxicity against Culicidae larvae. Both Cry48Aa1 and Tpp49Aa1 toxins are crucial for binding to the toxin receptor in Culex quinquefasciatus larvae, albeit with different binding sites. Previous studies have identified Glu71, a membrane-bound α-glucosidase, as a putative binding protein for the Cry48Aa1 toxin, involved in the Cry48Aa1/Tpp49Aa1 toxicity. In this study, we employed pulldown assays to identify a group of Tpp49Aa1-binding proteins from C. quinquefasciatus solubilized midgut brush-border membrane proteins (BBMFs). RNA interference assays revealed that the silencing of an alkaline phosphatase gene (referred to as ALP1263) in C. quinquefasciatus resulted in a significant reduction in larval mortality upon exposure to Cry48Aa1/Tpp49Aa1 toxin in vivo. Furthermore, the ALP1263 protein exhibited specific and high-affinity binding to the Tpp49Aa1 toxin, with a dissociation constant (Kd) of approximately 57.3 nM. The dot blot analysis demonstrated that Tpp49Aa1 C-terminal region was essential for its interaction with the ALP1263 protein. In summary, our findings establish ALP1263 as a functional receptor for Tpp49Aa1 and emphasize its role in the toxicity of Cry48Aa1/Tpp49Aa1.
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Affiliation(s)
- Qingyun Guo
- College of Life Sciences, Gannan Normal University, Ganzhou City, Jiangxi Province, 341000, PR China.
| | - Wei Li
- College of Life Sciences, Gannan Normal University, Ganzhou City, Jiangxi Province, 341000, PR China
| | - Yingchao Niu
- College of Life Sciences, Gannan Normal University, Ganzhou City, Jiangxi Province, 341000, PR China
| | - Xiaohua Dai
- College of Life Sciences, Gannan Normal University, Ganzhou City, Jiangxi Province, 341000, PR China
| | - Lin Chen
- College of Life Sciences, Gannan Normal University, Ganzhou City, Jiangxi Province, 341000, PR China
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Dechkla M, Charoenjotivadhanakul S, Imtong C, Visitsattapongse S, Li HC, Angsuthanasombat C. Cry4Aa and Cry4Ba Mosquito-Active Toxins Utilize Different Domains in Binding to a Particular Culex ALP Isoform: A Functional Toxin Receptor Implicating Differential Actions on Target Larvae. Toxins (Basel) 2022; 14:toxins14100652. [PMID: 36287921 PMCID: PMC9607545 DOI: 10.3390/toxins14100652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/10/2022] [Accepted: 09/16/2022] [Indexed: 11/16/2022] Open
Abstract
The three-domain Cry4Aa toxin produced from Bacillus thuringiensis subsp. israelensis was previously shown to be much more toxic to Culex mosquito larvae than its closely related toxin—Cry4Ba. The interaction of these two individual toxins with target receptors on susceptible larval midgut cells is likely to be the critical determinant in their differential toxicity. Here, two full-length membrane-bound alkaline phosphatase (mALP) isoforms from Culex quinquefasciatus larvae, Cq-mALP1263and Cq-mALP1264, predicted to be GPI-linked was cloned and functionally expressed in Spodoptera frugiperda (Sf9) cells as 57- and 61-kDa membrane-bound proteins, respectively. Bioinformatics analysis disclosed that both Cq-mALP isoforms share significant sequence similarity to Aedes aegypti-mALP—a Cry4Ba toxin receptor. In cytotoxicity assays, Sf9 cells expressing Cq-mALP1264, but not Cq-mALP1263, showed remarkably greater susceptibility to Cry4Aa than Cry4Ba, while immunolocalization studies revealed that both toxins were capable of binding to each Cq-mALP expressed on the cell membrane surface. Molecular docking of the Cq-mALP1264-modeled structure with individual Cry4 toxins revealed that Cry4Aa could bind to Cq-mALP1264 primarily through particular residues on three surface-exposed loops in the receptor-binding domain—DII, including Thr512, Tyr513 and Lys514 in the β10-β11loop. Dissimilarly, Cry4Ba appeared to utilize only certain residues in its C-terminal domain—DIII to interact with such a Culex counterpart receptor. Ala-substitutions of selected β10-β11loop residues (T512A, Y513A and K514A) revealed that only the K514A mutant displayed a drastic decrease in biotoxicity against C. quinquefasciatus larvae. Further substitution of Lys514 with Asp (K514D) revealed a further decrease in larval toxicity. Furthermore, in silico calculation of the binding affinity change (ΔΔGbind) in Cry4Aa-Cq-mALP1264 interactions upon these single-substitutions revealed that the K514D mutation displayed the largest ΔΔGbind value as compared to three other mutations, signifying an adverse impact of a negative charge at this critical receptor-binding position. Altogether, our present study has disclosed that these two related-Cry4 mosquito-active toxins conceivably exploited different domains in functional binding to the same Culex membrane-bound ALP isoform—Cq-mALP1264 for mediating differential toxicity against Culex target larvae.
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Affiliation(s)
- Manussawee Dechkla
- Department of Environmental Biology, Faculty of Science and Technology, Suan Sunandha Rajabhat University, Bangkok 10300, Thailand
- Correspondence: (M.D.); (C.A.)
| | - Sathapat Charoenjotivadhanakul
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand
| | - Chompounoot Imtong
- Laboratory of Structural Biochemistry and Cell Chemical Biology, Biophysics Institute for Research and Development (BIRD), Fang, Chiang Mai 50110, Thailand
| | - Sarinporn Visitsattapongse
- Department of Biomedical Engineering, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand
| | - Hui-Chun Li
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Chanan Angsuthanasombat
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand
- Laboratory of Structural Biochemistry and Cell Chemical Biology, Biophysics Institute for Research and Development (BIRD), Fang, Chiang Mai 50110, Thailand
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
- Correspondence: (M.D.); (C.A.)
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Guo Q, Gao Y, Xing C, Niu Y, Ding L, Dai X. Culex quinquefasciatus alpha-glucosidase serves as a putative receptor of the Cry48Aa toxin from Lysinibacillus sphaericus. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 147:103799. [PMID: 35662624 DOI: 10.1016/j.ibmb.2022.103799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 05/20/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
The Cry48Aa/Cry49Aa toxin of Lysinibacillus sphaericus shows specific toxicity towards larvae of Culex spp. Individual Cry48Aa and Cry49Aa subunits interact with distinct target sites in the larval midgut and overcome the resistance of Culex to the Bin toxin. However, the toxin-binding proteins have not yet been identified. The present study aimed to identify Cry48Aa-binding proteins in Culex quinquefasciatus. Pulldown assays using C. quinquefasciatus midgut brush-border membrane fractions (BBMFs) identified a class of proteins, including aminopeptidases (APNs), protease m1 zinc metalloproteases, alkaline phosphatases (ALPs), and maltases, that could be potentially involved in the mode of action of this toxin. RNA interference analysis showed that silenced larvae treated with dsRNA of the alpha-glucosidase (named Glu71) gene were more tolerant of the Cry48Aa/Cry49Aa toxin, which induced less than 20% mortality. The amino acid sequence of Glu71 exhibited 42% identity with Cqm1/Cpm1, which acted as a Bin toxin receptor. Toxin binding assays showed that Cry48Aa had a high specific binding capacity for the Glu71 protein, whereas Cry49Aa exhibited no specific binding. Overall, our results showed that Glu71 is a Cry48-binding protein involved in Cry48Aa/Cry49Aa toxicity.
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Affiliation(s)
- Qingyun Guo
- College of Life Sciences, Gannan Normal University, Ganzhou City of Jiangxi Province, 341000, PR China.
| | - Yuan Gao
- College of Life Sciences, Gannan Normal University, Ganzhou City of Jiangxi Province, 341000, PR China
| | - Chong Xing
- School of Information Engineering, Gannan Medical University, Ganzhou City of Jiangxi Province, 341000, PR China
| | - Yingchao Niu
- College of Life Sciences, Gannan Normal University, Ganzhou City of Jiangxi Province, 341000, PR China
| | - Lu Ding
- College of Life Sciences, Gannan Normal University, Ganzhou City of Jiangxi Province, 341000, PR China
| | - Xiaohua Dai
- College of Life Sciences, Gannan Normal University, Ganzhou City of Jiangxi Province, 341000, PR China
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Zhu Q, Gao M, Lu L, Liu X. Synergism of Bacillus thuringiensis Toxin Cry1Ac by a Fragment of Toxin-Binding Polycalin from Plutella xylostella. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:11816-11824. [PMID: 34596393 DOI: 10.1021/acs.jafc.1c03156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The continued success of pest control using insecticidal crystal (Cry) proteins from Bacillus thuringiensis (Bt) in transgenic plants was threatened by the evolution of resistance. Previous studies suggested that polycalin from Plutella xylostella could bind to Cry1Ac toxin as a potential receptor. In this study, a fragment of P. xylostella polycalin (Pxpolycalinf, G2209-A2942) containing a carboxyl-terminal GPI-anchored signal peptide was cloned and expressed. Purified Pxpolycalinf retained the binding ability to Cry1Ac and synergized Cry1Ac toxicity to the third larvae of P. xylostella in bioassays. Moreover, the polyclonal antibody of Pxpolycalinf decreased the Cry1Ac activity after being fed together with normal food. Further, the ELISA results showed the concentration-dependent binding of Pxpolycalinf to P. xylostella brush border membrane vesicles (BBMV). Spodoptera frugiperda 9 (Sf9) cells expressing Pxpolycalinf were not susceptive to Cry1Ac, whereas Pxpolycalinf increased Cry1Ac cytotoxicity to Sf9 cells expressing P. xylostella ATP-dependent binding cassette transporter C2 (PxABCC2). Immunolocalization presented the binding of Pxpolycalinf to the Sf9 cell membrane, and ELISA showed the concentration-dependent binding of Pxpolycalinf to Sf9 cell extraction. These results here provide the first evidence that a fragment of P. xylostella polycalin, a potential receptor of Cry1Ac, synergizes Cry1Ac toxicity to P. xylostella larvae and Sf9 cells expressing PxABCC2.
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Affiliation(s)
- Qing Zhu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro -product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Meijing Gao
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro -product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Lina Lu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro -product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xianjin Liu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro -product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
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Thammasittirong A, Thammasittirong SNR, Imtong C, Charoenjotivadhanakul S, Sakdee S, Li HC, Okonogi S, Angsuthanasombat C. Bacillus thuringiensis Cry4Ba Insecticidal ToxinExploits Leu 615 in Its C-Terminal Domain to Interact with a Target Receptor- Aedes aegypti Membrane-Bound Alkaline Phosphatase. Toxins (Basel) 2021; 13:toxins13080553. [PMID: 34437424 PMCID: PMC8402544 DOI: 10.3390/toxins13080553] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 11/16/2022] Open
Abstract
In addition to the receptor-binding domain (DII), the C-terminal domain (DIII) of three-domain Cry insecticidal δ-endotoxins from Bacillus thuringiensis has been implicated in target insect specificity, yet its precise mechanistic role remains unclear. Here, the 21 kDa high-purity isolated DIII fragment derived from the Cry4Ba mosquito-specific toxin was achieved via optimized preparative FPLC, allowing direct rendering analyses for binding characteristics toward its target receptor—Aedes aegypti membrane-bound alkaline phosphatase (Aa-mALP). Binding analysis via dotblotting revealed that the Cry4Ba-DIII truncate was capable of specific binding to nitrocellulose-bound Aa-mALP, with a binding signal comparable to its 65 kDa Cry4Ba-R203Q full-length toxin. Further determination of binding affinity via sandwich ELISA revealed that Cry4Ba-DIII exhibited a rather weak binding to Aa-mALP with a dissociation constant (Kd) of ≈1.1 × 10−7 M as compared with the full-length toxin. Intermolecular docking between the Cry4Ba-R203Q active toxin and Aa-mALP suggested that four Cry4Ba-DIII residues, i.e., Glu522, Asn552, Asn576, and Leu615, are potentially involved in such toxin–receptor interactions. Ala substitutions of each residue (E522A, N552A, N576A and L615A) revealed that only the L615A mutant displayed a drastic decrease in biotoxicity against A. aegypti larvae. Additional binding analysis revealed that the L615A-impaired toxin also exhibited a reduction in binding capability to the surface-immobilized Aa-mALP receptor, while two bio-inactive DII-mutant toxins, Y332A and F364A, which almost entirely lost their biotoxicity, apparently retained a higher degree of binding activity. Altogether, our data disclose a functional importance of the C-terminal domain of Cry4Ba for serving as a potential receptor-binding moiety in which DIII-Leu615 could conceivably be exploited for the binding to Aa-mALP, highlighting its contribution to toxin interactions with such a target receptor in mediating larval toxicity.
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Affiliation(s)
- Anon Thammasittirong
- Microbial Biotechnology Unit, Department of Microbiology, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom 73140, Thailand;
- Correspondence: (A.T.); (C.A.)
| | - Sutticha Na-Ranong Thammasittirong
- Microbial Biotechnology Unit, Department of Microbiology, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom 73140, Thailand;
| | - Chompounoot Imtong
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand;
| | - Sathapat Charoenjotivadhanakul
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand; (S.C.); (S.S.)
| | - Somsri Sakdee
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand; (S.C.); (S.S.)
| | - Hui-Chun Li
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan;
| | - Siriporn Okonogi
- Research Center of Pharmaceutical Nanotechnology, Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand;
| | - Chanan Angsuthanasombat
- Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Salaya Campus, Mahidol University, Nakorn Pathom 73170, Thailand; (S.C.); (S.S.)
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan;
- Laboratory of Synthetic Biophysics and Chemical Biology, Biophysics Institute for Research and Development (BIRD), Chiang Mai 50130, Thailand
- Correspondence: (A.T.); (C.A.)
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Bourchookarn W, Bourchookarn A, Imtong C, Li HC, Angsuthanasombat C. His 180 in the pore-lining α4 of the Bacillus thuringiensis Cry4Aa δ-endotoxin is crucial for structural arrangements of the α4-α5 transmembrane hairpin and hence biotoxicity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140634. [PMID: 33636413 DOI: 10.1016/j.bbapap.2021.140634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 10/22/2022]
Abstract
One proposed toxic mechanism of Bacillus thuringiensis Cry δ-endotoxins involves pore formation in target membranes by the α4-α5 transmembrane hairpin constituting their pore-forming domain. Here, nine selected charged and uncharged polar residues in the pore-lining α4 of the Cry4Aa mosquito-active toxin were substituted with Ala. All mutant toxins, i.e., D169A, R171A, Q173A, H178A, Y179A, H180A, Q182A, N183A and E187A, were over-expressed in Escherichia coli as 130-kDa protoxin inclusions at levels comparable to the wild-type toxin. Bioassays against Aedes aegypti larvae revealed that only H178A and H180A mutants displayed a drastic reduction in biotoxicity, albeit almost complete insolubility observed for H178A, but not for H180A inclusions. Further mutagenic analysis showed that replacements of His180 with charged (Arg, Lys, Asp, Glu), small uncharged polar (Ser, Cys) or small non-polar (Gly, Val) residues severely impaired the biotoxicity, unlike substitutions with relatively large uncharged (Asn, Gln, Leu) or aromatic (Phe, Tyr, Trp) residues. Similar to the trypsin-activated wild-type toxin, both bio-active and -inactive H180 mutants were still capable of releasing entrapped calcein from lipid vesicles and producing cation-selective channels with ~130-pS maximum conductance. Analysis of the Cry4Aa structure revealed the existence of a hydrophobic cavity near the critical His180 side-chain. Analysis of simulated structures revealed that His180-to-smaller residue conversions create a gap disrupting such cavity's hydrophobicity and hence structural arrangements of the α4-α5 hairpin. Altogether, our data disclose a critical involvement in Cry4Aa-biotoxicity of His180 exclusively present in the lumen-facing α4 for providing proper environment for the α4-α5 hairpin prior to membrane-inserted pore formation.
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Affiliation(s)
- Walairat Bourchookarn
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand
| | - Apichai Bourchookarn
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand.
| | - Chompounoot Imtong
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand
| | - Hui-Chun Li
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Chanan Angsuthanasombat
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan; Laboratory of Synthetic Biophysics and Chemical Biology, Biophysics Institute for Research and Development (BIRD), Chiang Mai 50230, Thailand; Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
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Hao J, Gao M, Hu X, Lu L, Zhang X, Liu Y, Zhong J, Liu X. Synergistic selection of a Helicoverpa armigera cadherin fragment with Cry1Ac in different cells and insects. Int J Biol Macromol 2020; 164:3667-3675. [PMID: 32853622 DOI: 10.1016/j.ijbiomac.2020.08.175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 08/20/2020] [Accepted: 08/21/2020] [Indexed: 10/23/2022]
Abstract
The midgut cadherin fragments were extensively studied as Bt synergists in insects, while their synergistic selection modes with Bt toxins in different mechanisms of resistance or insects have never been determined. Here, a soluble Helicoverpa armigera cadherin fragment which corresponds to the Cry1Ac binding region (HaCad-TBR) was expressed in Escherichia coli and its synergism with Cry1Ac toxin in H. armigera and Plutella xylostella larvae as well as Sf9 cells expressing different cadherins was tested. HaCad-TBR exhibited higher synergism factor in P. xylostella larvae (4.84-fold) than in H. armigera larvae (2.45-fold). Among the cells expressing HaCad alleles, HaCad-TBR enhanced the Cry1Ac toxicity only in the cells expressing the mutant lacking the extracellular domain. Moreover, HaCad-TBR had a weak enhancement of Cry1Ac toxicity in Sf9 cells expressing the P. xylostella cadherin. Further researches revealed that the enhancement of toxicity in Sf9 cells was correlated with increased toxin binding. These results suggested that cadherin fragments which have high binding level with Cry1Ac are more likely to enhance toxin toxicity well against the cells or larvae where the cadherin has lower binding level with Cry1Ac, especially in the cases lacking the toxin binding domain.
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Affiliation(s)
- Jia Hao
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Meijing Gao
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xiaodan Hu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Lina Lu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xiao Zhang
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Yuan Liu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Jianfeng Zhong
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Xianjin Liu
- Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Key Laboratory of Control Technology and Standard for Agro-product Safety and Quality, Ministry of Agriculture, Institute of Food Safety and Nutrition, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
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Shi J, Peng D, Zhang F, Ruan L, Sun M. The Caenorhabditis elegans CUB-like-domain containing protein RBT-1 functions as a receptor for Bacillus thuringiensis Cry6Aa toxin. PLoS Pathog 2020; 16:e1008501. [PMID: 32369532 PMCID: PMC7228132 DOI: 10.1371/journal.ppat.1008501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 05/15/2020] [Accepted: 03/26/2020] [Indexed: 12/16/2022] Open
Abstract
Plant-parasitic nematodes cause huge agricultural economic losses. Two major families of Bacillus thuringiensis crystal proteins, Cry5 and Cry6, show nematicidal activity. Previous work showed that binding to midgut receptors is a limiting step in Cry toxin mode of action. In the case of Cry5Ba, certain Caenorhabditis elegans glycolipids were identified as receptors of this toxin. However, the receptors for Cry6 toxin remain unknown. In this study, the C. elegans CUB-like-domain containing protein RBT-1, released by phosphatidylinositol-specific phospholipase C (PI-PLC), was identified as a Cry6Aa binding protein by affinity chromatography. RBT-1 contained a predicted glycosylphosphatidylinositol (GPI) anchor site and was shown to locate in lipid rafts in the surface of the midgut cells. Western ligand blot assays and ELISA binding analysis confirmed the binding interaction between Cry6Aa and RBT-1 showing high affinity and specificity. In addition, the mutation of rbt-1 gene decreased the susceptibility of C. elegans to Cry6Aa but not that of Cry5Ba. Furthermore, RBT-1 mediated the uptake of Cry6Aa into C. elegans gut cells, and was shown to be involved in triggering pore-formation activity, indicating that RBT-1 is required for the interaction of Cry6Aa with the nematode midgut cells. These results support that RBT-1 is a functional receptor for Cry6Aa. Bacillus thuringiensis (Bt) crystal proteins belong to pore-forming toxins (PFTs), which display virulence against target hosts by forming holes in the cell membrane. Cry6A is a nematicidal PFT, which exhibits unique protein structure and different mode of action than Cry5B, another nematicidal PFT. However, little is known about the mode of action of Cry6A. Although an intracellular nematicidal necrosis pathway of Cry6A was reported, its extracellular mode of action remains unknown. We here demonstrate that the CUB-like-domain containing protein RBT-1 acts as a functional receptor of Cry6A, which mediates the intestinal cell interaction and nematicidal activity of this toxin. RBT-1 represents a new class of crystal protein receptors. RBT-1 is dispensable for Cry5B toxicity against nematodes, consistent with that Cry6A and Cry5B have different nematicidal mechanisms. We also find that Cry6A kills nematodes by complex mechanism since rbt-1 mutation did not affect Cry6A-mediated necrosis signaling pathway. This work not only enhances the understanding of Bt crystal protein-nematode mechanism, but is also in favor for the application of Cry6A in nematode control.
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Affiliation(s)
- Jianwei Shi
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Donghai Peng
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- * E-mail: (DP); (MS)
| | - Fengjuan Zhang
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Ming Sun
- State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
- * E-mail: (DP); (MS)
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da Silva G, Costa Ramos LF, Dos Santos Seckler H, Mendonça Gomes F, Reis Cortines J, Ramos I, Dinis Anobom C, de Alcantara Machado E, Perpétua de Oliveira DM. Biochemical characterization of digestive membrane-associated alkaline phosphatase from the velvet bean caterpillar Anticarsia gemmatalis. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 102:e21591. [PMID: 31257641 DOI: 10.1002/arch.21591] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In Brazil, the use of transgenic plants expressing the insect-toxic Bacillus thuringiensis endotoxin has been successfully used as pest control management since 2013 in transgenic soybean lineages against pest caterpillars such as Helicoverpa armigera. These toxins, endogenously expressed by the plants or sprayed over the crops, are ingested by the insect and bind to receptors in the midgut of these animals, resulting in disruption of digestion and lower insect survival rates. Here, we identified and characterized a membrane-associated alkaline phosphatase (ALP) in the midgut of Anticarsia gemmatalis, the main soybean defoliator pest in Brazil, and data suggested that it binds to Cry1Ac toxin in vitro. Our data showed a peak of ALP activity in homogenate samples of the midgut dissected from the 4th and 5th instars larvae. The brush border membrane vesicles obtained from the midgut of these larvae were used to purify a 60 kDa ALP, as detected by in-gel activity and in vitro biochemical characterization using pharmacological inhibitors and mass spectrometry. When Cry1Ac toxin was supplied to the diet, it was efficient in decreasing larval weight gain and survival. Indeed, in vitro incubation of Cry1Ac toxin with the purified ALP resulted in a 43% decrease in ALP specific activity and enzyme-linked immunosorbent assay showed that ALP interacts with Cry1Ac toxin in vitro, thus suggesting that ALP could function as a Cry toxin ligand. This is a first report characterizing an ALP in A. gemmatalis.
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Affiliation(s)
- Gabriela da Silva
- Laboratório de Bioquímica Estrutural de Proteínas, Departamento de Bioquímica, Centro de Ciências Matemáticas e da Natureza, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Luís Felipe Costa Ramos
- Laboratório de Bioquímica Estrutural de Proteínas, Departamento de Bioquímica, Centro de Ciências Matemáticas e da Natureza, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Henrique Dos Santos Seckler
- Laboratório de Bioquímica Estrutural de Proteínas, Departamento de Bioquímica, Centro de Ciências Matemáticas e da Natureza, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Fabio Mendonça Gomes
- Laboratório de Bioquímica de Insetos e Parasitos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Juliana Reis Cortines
- Departamento de Virologia, Centro de Ciências da Saúde, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Isabela Ramos
- Laboratório de Bioquímica de Insetos, Centro de Ciências da Saúde, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Cristiane Dinis Anobom
- Laboratório de Bioquímica Estrutural de Proteínas, Departamento de Bioquímica, Centro de Ciências Matemáticas e da Natureza, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Ednildo de Alcantara Machado
- Laboratório de Bioquímica de Insetos e Parasitos, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
| | - Danielle Maria Perpétua de Oliveira
- Laboratório de Bioquímica Estrutural de Proteínas, Departamento de Bioquímica, Centro de Ciências Matemáticas e da Natureza, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro CEP, Brazil
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10
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Ren XL, Hu HY, Jiang WL, Ma XY, Ma YJ, Li GQ, Ma Y. Three GPI-anchored alkaline phosphatases are involved in the intoxication of Cry1Ca toxin to Spodoptera exigua larvae. J Invertebr Pathol 2018; 151:32-40. [DOI: 10.1016/j.jip.2017.10.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 10/22/2017] [Accepted: 10/26/2017] [Indexed: 02/08/2023]
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11
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Chen J, Aimanova K, Gill SS. Functional characterization of Aedes aegypti alkaline phosphatase ALP1 involved in the toxicity of Cry toxins from Bacillus thuringiensis subsp. israelensis and jegathesan. Peptides 2017; 98:78-85. [PMID: 28587836 PMCID: PMC5705450 DOI: 10.1016/j.peptides.2017.05.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 05/24/2017] [Accepted: 05/30/2017] [Indexed: 10/19/2022]
Abstract
Presently three major groups of proteins from Aedes aegypti, cadherin, alkaline phosphatases (ALP) and aminopeptidases N (APN), have been identified as Cry11Aa toxin receptors. To further characterize their role on toxicity, transgenic mosquitoes with silenced Aedes cadherin expression were previously generated and the role of cadherin in mediating the toxicity of four different mosquitocidal toxins (Cry11Aa, Cry11Ba, Cry4Aa and Cry4Ba) was demonstrated. Here, we investigated the role of another reported Cry11Aa receptor, ALP1. As with Aedes cadherin, this protein is localized in the apical cell membrane of distal and proximal gastric caecae and the posterior midgut. We also successfully generated transgenic mosquitoes that knockdowned ALP1 transcript levels using an inducible Aedes heat shock promoter, Hsp70A driving dsALP1RNA. Four different mosquitocidal toxins were used for larval bioassays against this transgenic mosquito. Bioassay results show thatCry11Aa toxicity to these transgenic larvae following a heat shock decreased (4.4 fold) and Cry11Ba toxicity is slightly attenuated. But Cry4Aa and Cry4Ba toxicity to ALP1 silenced larvae is unchanged. Without heat shock, toxicity of all four toxins does not change, suggesting this heat shock promoter is heat-inducible. Notably, transgenic mosquitoes with ALP1 knockdown are about 3.7 times less resistant to Cry11Aa toxin than those with Aedes cadherin knockdown. These results demonstrate that the ALP1 is an important secondary receptor for Cry11Aa and Cry11Ba, but it might not be involved in Cry4Aa and Cry4Ba toxicity.
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Affiliation(s)
- Jianwu Chen
- Departmentof Cell Biology and Neurosciences, University of California, Riverside, CA 92521, United States.
| | - Karly Aimanova
- Departmentof Cell Biology and Neurosciences, University of California, Riverside, CA 92521, United States
| | - Sarjeet S Gill
- Departmentof Cell Biology and Neurosciences, University of California, Riverside, CA 92521, United States
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12
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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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13
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Rezende TMT, Romão TP, Batista M, Berry C, Adang MJ, Silva-Filha MHNL. Identification of Cry48Aa/Cry49Aa toxin ligands in the midgut of Culex quinquefasciatus larvae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 88:63-70. [PMID: 28780070 DOI: 10.1016/j.ibmb.2017.08.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/15/2017] [Accepted: 08/01/2017] [Indexed: 06/07/2023]
Abstract
A binary mosquitocidal toxin composed of a three-domain Cry-like toxin (Cry48Aa) and a binary-like toxin (Cry49Aa) was identified in Lysinibacillus sphaericus. Cry48Aa/Cry49Aa has action on Culex quinquefasciatus larvae, in particular, to those that are resistant to the Bin Binary toxin, which is the major insecticidal factor from L. sphaericus-based biolarvicides, indicating that Cry48Aa/Cry49Aa interacts with distinct target sites in the midgut and can overcome Bin toxin resistance. This study aimed to identify Cry48Aa/Cry49Aa ligands in C. quinquefasciatus midgut through binding assays and mass spectrometry. Several proteins, mostly from 50 to 120 kDa, bound to the Cry48Aa/Cry49Aa toxin were revealed by toxin overlay and pull-down assays. These proteins were identified against the C. quinquefasciatus genome and after analysis a set of 49 proteins were selected which includes midgut bound proteins such as aminopeptidases, amylases, alkaline phosphatases in addition to molecules from other classes that can be potentially involved in this toxin's mode of action. Among these, some proteins are orthologs of Cry receptors previously identified in mosquito larvae, as candidate receptors for Cry48Aa/Cry49Aa toxin. Further investigation is needed to evaluate the specificity of their interactions and their possible role as receptors.
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Affiliation(s)
| | | | - Michel Batista
- Instituto Carlos Chagas-FIOCRUZ, Curitiba, PR 81350-010, Brazil
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Cardiff, CF10 3AT, United Kingdom
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14
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Zhao M, Yuan X, Wei J, Zhang W, Wang B, Myint Khaing M, Liang G. Functional roles of cadherin, aminopeptidase-N and alkaline phosphatase from Helicoverpa armigera (Hübner) in the action mechanism of Bacillus thuringiensis Cry2Aa. Sci Rep 2017; 7:46555. [PMID: 28488696 PMCID: PMC5424343 DOI: 10.1038/srep46555] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/17/2017] [Indexed: 11/08/2022] Open
Abstract
A pyramid strategy combining the Cry1A and Cry2A toxins in Bt crops has been widely used throughout the world to delay pest adaption to transgenic crops and broaden the insecticidal spectrum. Midgut membrane-bound cadherin (CAD), aminopeptidase-N (APN) and alkaline phosphatase (ALP) are important for Cry1A toxicity in some lepidopteran larvae, but the proteins that bind Cry2A in the midgut of target insects and their role in the Cry2A mechanism of action are still unclear. In this study, we found that heterologously expressed CAD, APN4 and ALP2 peptides from the midgut of Helicoverpa armigera could bind to the Cry2Aa toxin with a high affinity. Additionally, the efficiency of Cry2Aa insecticidal activity against H. armigera larvae was obviously reduced after the genes encoding these proteins were silenced with specific siRNAs: CAD- and ALP2-silenced larvae showed significantly similar reductions in mortality due to the Cry2Aa toxin (41.67% and 43.06%, respectively), whereas a larger reduction in mortality was observed in APN4-silenced larvae (61.11%) than in controls. These results suggest that CAD, APN4 and ALP2 are involved in the mechanism of action of Cry2Aa in H. armigera and may play important functional roles in the toxicity of the Cry2Aa toxin.
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Affiliation(s)
- Man Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiangdong Yuan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jizhen Wei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Wanna Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bingjie Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Myint Myint Khaing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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15
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Yuan X, Zhao M, Wei J, Zhang W, Wang B, Myint Khaing M, Liang G. New insights on the role of alkaline phosphatase 2 from Spodoptera exigua (Hübner) in the action mechanism of Bt toxin Cry2Aa. JOURNAL OF INSECT PHYSIOLOGY 2017; 98:101-107. [PMID: 28034678 DOI: 10.1016/j.jinsphys.2016.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 12/19/2016] [Accepted: 12/22/2016] [Indexed: 06/06/2023]
Abstract
Cry1A and Cry2A toxins, which are widely used in Bt transgenic crops, can specifically bind to insect midguts and exert their insecticidal effects. There are interactions between insect midgut-binding proteins and Cry1A toxins; however, little is known about the insect protein that specifically binds to Cry2A. Midgut membrane-bound alkaline phosphatases (ALPs), which are important for the binding of proteins to Cry1A, play dominant roles in Cry1A-mediated toxicity in some lepidopteran larvae. In this study, we cloned and expressed one partial ALP2 peptide from susceptible Spodoptera exigua larvae and studied the binding characteristics of SeALP2 with Cry2Aa. The ALPs proteins was expressed at all larval stages and highly expressed in the first and second instar larvae. The heterologously expressed SeALP2 peptide bound specifically to Cry2Aa with a high affinity. Knocking down ALP2 in vivo revealed that it plays an important role in the susceptibility of S. exigua to Cry2Aa. Based on these findings, we propose that ALP2 in S. exigua serves as a functional receptor for Cry2Aa.
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Affiliation(s)
- Xiangdong Yuan
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Man Zhao
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jizhen Wei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wanna Zhang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bingjie Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Myint Myint Khaing
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Gemei Liang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
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16
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Atkinson SC, Armistead JS, Mathias DK, Sandeu MM, Tao D, Borhani-Dizaji N, Tarimo BB, Morlais I, Dinglasan RR, Borg NA. The Anopheles-midgut APN1 structure reveals a new malaria transmission-blocking vaccine epitope. Nat Struct Mol Biol 2015; 22:532-9. [PMID: 26075520 PMCID: PMC4547048 DOI: 10.1038/nsmb.3048] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/18/2015] [Indexed: 12/31/2022]
Abstract
Mosquito-based malaria transmission-blocking vaccines (mTBVs) target midgut-surface antigens of the Plasmodium parasite's obligate vector, the Anopheles mosquito. The alanyl aminopeptidase N (AnAPN1) is the leading mTBV immunogen; however, AnAPN1's role in Plasmodium infection of the mosquito and how anti-AnAPN1 antibodies functionally block parasite transmission have remained elusive. Here we present the 2.65-Å crystal structure of AnAPN1 and the immunoreactivity and transmission-blocking profiles of three monoclonal antibodies (mAbs) to AnAPN1, including mAb 4H5B7, which effectively blocks transmission of natural strains of Plasmodium falciparum. Using the AnAPN1 structure, we map the conformation-dependent 4H5B7 neoepitope to a previously uncharacterized region on domain 1 and further demonstrate that nonhuman-primate neoepitope-specific IgG also blocks parasite transmission. We discuss the prospect of a new biological function of AnAPN1 as a receptor for Plasmodium in the mosquito midgut and the implications for redesigning the AnAPN1 mTBV.
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Affiliation(s)
- Sarah C Atkinson
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Jennifer S Armistead
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Derrick K Mathias
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Maurice M Sandeu
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche pour le Développement-Organisation de Coordination et de Coopération pour la Lutte Contre les Grandes Endémies en Afrique Centrale, Yaoundé, Cameroon
| | - Dingyin Tao
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Nahid Borhani-Dizaji
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Brian B Tarimo
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [3] Nelson Mandela African Institute for Science and Technology, Arusha, Tanzania. [4] Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Isabelle Morlais
- Laboratoire de Recherche sur le Paludisme, Institut de Recherche pour le Développement-Organisation de Coordination et de Coopération pour la Lutte Contre les Grandes Endémies en Afrique Centrale, Yaoundé, Cameroon
| | - Rhoel R Dinglasan
- 1] W. Harry Feinstone Department of Molecular Microbiology &Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA. [2] Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Natalie A Borg
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
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17
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Zhang Q, Hua G, Adang MJ. Chitosan/DsiRNA nanoparticle targeting identifies AgCad1 cadherin in Anopheles gambiae larvae as an in vivo receptor of Cry11Ba toxin of Bacillus thuringiensis subsp. jegathesan. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2015; 60:33-38. [PMID: 25758367 DOI: 10.1016/j.ibmb.2015.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 02/18/2015] [Accepted: 03/01/2015] [Indexed: 06/04/2023]
Abstract
The Cry11Ba protein of Bacillus thuringiensis subsp. jegathesan crystals has uniquely high toxicity against a spectrum of mosquito species. The high potency of Cry11Ba against Anopheles gambiae is caused by recognition of multiple midgut proteins including glycosyl phosphatidylinositol-anchored alkaline phosphatase AgALP1, aminopeptidase AgAPN2, α-amylase AgAmy1 and α-glucosidase Agm3 that bind Cry11Ba with high affinity and function as putative receptors. The cadherin AgCad2 in An. gambiae larvae also binds Cry11Ba with high affinity (Kd = 12 nM) and is considered a putative receptor, while cadherin AgCad1 bound Cry11Ba with low affinity (Kd = 766 nM), a property not supportive for a Cry11Ba receptor role. Here, we show the in vivo involvement of AgCad1 in Cry11Ba toxicity in An. gambiae larvae using chitosan/DsiRNA nanoparticles to inhibit AgCad expression in larvae. Cry11Ba was significantly less toxic to AgCad1-silenced larvae than to control larvae. Because AgCad1 was co-suppressed by AgCad2 DsRNAi, the involvement of AgCad2 in Cry11Ba toxicity could not be ascertained. The ratio of AgCad1:AgCad2 transcript level is 36:1 for gut tissue in 4th instar larvae. Silencing AgCad expression had no effect on transcript levels of other binding receptors of Cry11Ba. We conclude that AgCad1 and possibly AgCad2 in An. gambiae larvae are functional receptors of Cry11Ba toxin in vivo.
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Affiliation(s)
- Qi Zhang
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA
| | - Gang Hua
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA
| | - Michael J Adang
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA; Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602-2603, USA.
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18
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A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera. PLoS One 2015; 10:e0126288. [PMID: 25885820 PMCID: PMC4401514 DOI: 10.1371/journal.pone.0126288] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 03/31/2015] [Indexed: 11/19/2022] Open
Abstract
Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.
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19
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Aroonkesorn A, Pootanakit K, Katzenmeier G, Angsuthanasombat C. Two specific membrane-bound aminopeptidase N isoforms from Aedes aegypti larvae serve as functional receptors for the Bacillus thuringiensis Cry4Ba toxin implicating counterpart specificity. Biochem Biophys Res Commun 2015; 461:300-6. [PMID: 25871797 PMCID: PMC7124302 DOI: 10.1016/j.bbrc.2015.04.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 04/05/2015] [Indexed: 12/28/2022]
Abstract
The interaction between Bacillus thuringiensis Cry toxins and their receptors on midgut cells of susceptible insect larvae is the critical determinant in toxin specificity. Besides GPI-linked alkaline phosphatase in Aedes aegypti mosquito-larval midguts, membrane-bound aminopeptidase N (AaeAPN) is widely thought to serve as a Cry4Ba receptor. Here, two full-length AaeAPN isoforms, AaeAPN2778 and AaeAPN2783, predicted to be GPI-linked were cloned and successfully expressed in Spodoptera frugiperda (Sf9) cells as 112- and 107-kDa membrane-bound proteins, respectively. In the cytotoxicity assay, Sf9 cells expressing each of the two AaeAPN isoforms showed increased sensitivity to the Cry4Ba mosquito-active toxin. Double immunolocalization revealed specific binding of Cry4Ba to each individual AaeAPN expressed on the cell membrane surface. Sequence analysis and homology-based modeling placed these two AaeAPNs to the M1 aminopeptidase family as they showed similar four-domain structures, with the most conserved domain II being the catalytic component. Additionally, the most variable domain IV containing negatively charged surface patches observed only in dipteran APNs could be involved in insect specificity. Overall results demonstrated that these two membrane-bound APN isoforms were responsible for mediating Cry4Ba toxicity against AaeAPN-expressed Sf9 cells, suggesting their important role as functional receptors for the toxin counterpart in A. aegypti mosquito larvae. Two novel Aedes GPI-APN isoforms were functionally expressed in Sf9 cells. Cells expressing each AaeAPN were more sensitive to Cry4Ba toxin cytolysis. Specific binding of Cry4Ba to individual AaeAPN-expressing Sf9 cells was demonstrated. These two AaeAPNs mediating Cry4Ba cytotoxicity serve as receptors in Aedes larvae. AaeAPN models reveal four-domain organization with implications for toxin-counterpart specificity.
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Affiliation(s)
- Aratee Aroonkesorn
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
| | - Kusol Pootanakit
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
| | - Gerd Katzenmeier
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
| | - Chanan Angsuthanasombat
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand; Laboratory of Molecular Biophysics and Structural Biochemistry, Biophysics Institute for Research and Development (BIRD), Bangkok 10160, Thailand.
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20
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Chen J, Likitvivatanavong S, Aimanova KG, Gill SS. A 104 kDa Aedes aegypti aminopeptidase N is a putative receptor for the Cry11Aa toxin from Bacillus thuringiensis subsp. israelensis. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1201-8. [PMID: 24128608 PMCID: PMC3872109 DOI: 10.1016/j.ibmb.2013.09.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/20/2013] [Accepted: 09/27/2013] [Indexed: 05/25/2023]
Abstract
The Cry11Aa protein produced in Bacillus thuringiensis subsp. israelensis, a bacterial strain used worldwide for the control of Aedes aegypti larvae, binds midgut brush border membrane vesicles (BBMV) with an apparent K(d) of 29.8 nM. Previously an aminopeptidase N (APN), named AaeAPN2, was identified as a putative Cry11Aa toxin binding protein by pull-down assays using biotinylated Cry11Aa toxin (Chen et al., 2009. Insect Biochem. Mol. Biol. 39, 688-696). Here we show this protein localizes to the apical membrane of epithelial cells in proximal and distal regions of larval caeca. The AaeAPN2 protein binds Cry11Aa with high affinity, 8.6 nM. The full-length and fragments of AaeAPN2 were cloned and expressed in Escherichia coli. The toxin-binding region was identified and further competitive assays demonstrated that Cry11Aa binding to BBMV was efficiently competed by the full-length AaeAPN2 and the fragments of AaeAPN2b and AaeAPN2e. In bioassays against Ae. aegypti larvae, the presence of full-length and a partial fragment (AaeAPN2b) of AaeAPN2 enhanced Cry11Aa larval mortality. Taken together, we conclude that AaeAPN2 is a binding protein and plays a role in Cry11Aa toxicity.
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Affiliation(s)
| | | | | | - Sarjeet S. Gill
- Corresponding author: Sarjeet Gill, . Tel: 951-827-4621/3547
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RNA interference of cadherin gene expression in Spodoptera exigua reveals its significance as a specific Bt target. J Invertebr Pathol 2013; 114:285-91. [DOI: 10.1016/j.jip.2013.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 09/04/2013] [Accepted: 09/11/2013] [Indexed: 01/19/2023]
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Zhang Q, Hua G, Bayyareddy K, Adang MJ. Analyses of α-amylase and α-glucosidase in the malaria vector mosquito, Anopheles gambiae, as receptors of Cry11Ba toxin of Bacillus thuringiensis subsp. jegathesan. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:907-915. [PMID: 23872242 DOI: 10.1016/j.ibmb.2013.07.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 06/28/2013] [Accepted: 07/08/2013] [Indexed: 06/02/2023]
Abstract
Bacillus thuringiensis subsp. jegathesan produces Cry11Ba crystal protein with high toxicity to mosquito larvae. The Cry11Ba toxicity is dependent on its receptors on mosquito larval midgut epithelial cells. Previously, a cadherin-like protein (AgCad2), aminopeptidase (AgAPN2) and alkaline phosphatase (AgALP1) were reported to be involved in regulation of Cry11Ba toxicity on Anopheles gambiae larvae. Here, the cDNAs encoding α-amylase (AgAmy1) and α-glucosidase (Agm3) were cloned from A. gambiae larva midgut. Both are glycophosphatidylinositol (GPI) anchored proteins on brush border membranes (BBMV). Immunohistochemistry revealed their localization on different regions of the larval midgut. AgAmy1 and Agm3 bound Cry11Ba with high affinity, 37.6 nM and 21.1 nM respectively. Cry11Ba toxicity against A. gambiae larvae was neutralized by both AgAmy1 and Agm3. The results provide evidence that both AgAmy1 and Agm3 function as receptors of Cry11Ba in A. gambiae.
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Affiliation(s)
- Qi Zhang
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA
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Hua G, Zhang Q, Zhang R, Abdullah AM, Linser PJ, Adang MJ. AgCad2 cadherin in Anopheles gambiae larvae is a putative receptor of Cry11Ba toxin of Bacillus thuringiensis subsp. jegathesan. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:153-161. [PMID: 23231770 DOI: 10.1016/j.ibmb.2012.11.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/22/2012] [Accepted: 11/30/2012] [Indexed: 06/01/2023]
Abstract
In an effort to study the mode of action of Cry11Ba, we identified toxin binding proteins in Anopheles gambiae larval midgut and investigated their receptor roles. Previously, an aminopeptidase (AgAPN2) and an alkaline phosphatase (AgALP1) were identified as receptors for Cry11Ba toxin in A. gambiae. However, an A. gambiae cadherin (AgCad1) that bound Cry11Ba with low affinity (K(d) = 766 nM) did not support a receptor role of AgCad1 for Cry11Ba. Here, we studied a second A. gambiae cadherin (AgCad2) that shares 14% identity to AgCad1. Immunohistochemical study showed that the protein is localized on A. gambiae larval midgut apical membranes. Its cDNA was cloned and the protein was analyzed as a transmembrane protein containing 14 cadherin repeats. An Escherichia coli expressed CR14MPED fragment of AgCad2 bound Cry11Ba with high affinity (K(d) = 11.8 nM), blocked Cry11Ba binding to A. gambiae brush border vesicles and reduced Cry11Ba toxicity in bioassays. Its binding to Cry11Ba could be completely competed off by AgCad1, but only partially competed by AgALP1. The results are evidence that AgCad2 may function as a receptor for Cry11Ba in A. gambiae larvae.
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Affiliation(s)
- Gang Hua
- Department of Entomology, University of Georgia, Athens, GA 30602-2603, USA
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Tetreau G, Bayyareddy K, Jones CM, Stalinski R, Riaz MA, Paris M, David JP, Adang MJ, Després L. Larval midgut modifications associated with Bti resistance in the yellow fever mosquito using proteomic and transcriptomic approaches. BMC Genomics 2012; 13:248. [PMID: 22703117 PMCID: PMC3460780 DOI: 10.1186/1471-2164-13-248] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 05/25/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bacillus thuringiensis var. israelensis (Bti) is a natural larval mosquito pathogen producing pore-forming toxins targeting the midgut of Diptera larvae. It is used worldwide for mosquito control. Resistance mechanisms of an Aedes aegypti laboratory strain selected for 30 generations with field-collected leaf litter containing Bti toxins were investigated in larval midguts at two levels: 1. gene transcription using DNA microarray and RT-qPCR and 2. differential expression of brush border membrane proteins using DIGE (Differential In Gel Electrophoresis). RESULTS Several Bti Cry toxin receptors including alkaline phosphatases and N-aminopeptidases and toxin-binding V-ATPases exhibited altered expression levels in the resistant strain. The under-expression of putative Bti-receptors is consistent with Bt-resistance mechanisms previously described in Lepidoptera. Four soluble metalloproteinases were found under-transcribed together with a drastic decrease of metalloproteinases activity in the resistant strain, suggesting a role in resistance by decreasing the amount of activated Cry toxins in the larval midgut. CONCLUSIONS By combining transcriptomic and proteomic approaches, we detected expression changes at nearly each step of the ingestion-to-infection process, providing a short list of genes and proteins potentially involved in Bti-resistance whose implication needs to be validated. Collectively, these results open the way to further functional analyses to better characterize Bti-resistance mechanisms in mosquitoes.
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Affiliation(s)
- Guillaume Tetreau
- Laboratoire d'Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09, France.
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Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding. Appl Microbiol Biotechnol 2011; 93:2365-75. [DOI: 10.1007/s00253-011-3547-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 08/01/2011] [Accepted: 08/13/2011] [Indexed: 02/08/2023]
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Aedes aegypti membrane-bound alkaline phosphatase expressed in Escherichia coli retains high-affinity binding for Bacillus thuringiensis Cry4Ba toxin. Appl Environ Microbiol 2011; 77:6836-40. [PMID: 21856837 DOI: 10.1128/aem.05775-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glycosylphosphatidylinositol-linked alkaline phosphatase (GPI-ALP) from the epithelial membrane of the larval midgut of Aedes aegypti was previously identified as a functional receptor of the Bacillus thuringiensis Cry4Ba toxin. Here, heterologous expression in Escherichia coli of the cloned ALP, lacking the secretion signal and GPI attachment sequences, and assessment of its binding characteristics were further investigated. The 54-kDa His tag-fused ALP overexpressed as an inclusion body was soluble when phosphate buffer (pH 7.5) was supplemented with 8 M urea. After renaturation in a nickel-nitrilotriacetic acid (Ni-NTA) affinity column, the refolded ALP protein was able to retain its phosphatase activity. This refolded ALP also showed binding to the 65-kDa activated Cry4Ba toxin under nondenaturing (dot blot) conditions. Quantitative binding analysis using a quartz crystal microbalance revealed that the purified ALP immobilized on a gold electrode was bound by the Cry4Ba toxin in a stoichiometry of approximately 1:2 and with high affinity (dissociation constant [K(d)] of ∼14 nM) which is comparable to that calculated from kinetic parameters (dissociation rate constant [k(off)]/binding constant [k(on)]). Altogether, the data presented here of the E. coli-expressed ALP from A. aegypti retaining high-affinity toxin binding support our notion that glycosylation of this receptor is not required for binding to its counterpart toxin, Cry4Ba.
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Valaitis AP. Localization of Bacillus thuringiensis Cry1A toxin-binding molecules in gypsy moth larval gut sections using fluorescence microscopy. J Invertebr Pathol 2011; 108:69-75. [PMID: 21767544 DOI: 10.1016/j.jip.2011.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 06/16/2011] [Accepted: 07/01/2011] [Indexed: 11/28/2022]
Abstract
The microbial insecticide Bacillus thuringiensis (Bt) produces Cry toxins, proteins that bind to the brush border membranes of gut epithelial cells of insects that ingest it, disrupting the integrity of the membranes, and leading to cell lysis and insect death. In gypsy moth, Lymantria dispar, two toxin-binding molecules for the Cry1A class of Bt toxins have been identified: an aminopeptidase N (APN-1) and a 270kDa anionic glycoconjugate (BTR-270). Studies have shown that APN-1 has a relatively weak affinity and a very narrow specificity to Cry1Ac, the only Cry1A toxin that it binds. In contrast, BTR-270 binds all toxins that are active against L. dispar larvae, and the affinities for these toxins to BTR-270 correlate positively with their respective toxicities. In this study, an immunohistochemical approach was coupled with fluorescence microscopy to localize APN-1 and BTR-270 in paraffin embedded midgut sections of L. dispar larvae. The distribution of cadherin and alkaline phosphatase in the gut tissue was also examined. A strong reaction indicative of polyanionic material was detected with alcian blue staining over the entire epithelial brush border, suggesting the presence of acidic glycoconjugates in the microvillar matrix. The Cry1A toxin-binding sites were confined to the apical surface of the gut epithelial cells with intense labeling of the apical tips of the microvilli. APN-1, BTR-270, and alkaline phosphatase were found to be present exclusively along the brush border microvilli along the entire gut epithelium. In contrast, cadherin, detected only in older gypsy moth larvae, was present both in the apical brush border and in the basement membrane anchoring the midgut epithelial cells. The topographical relationship between the Bt Cry toxin-binding molecules BTR-270 and APN-1 and the Cry1A toxin-binding sites that were confined to the apical brush border of the midgut cells is consistent with findings implicating their involvement in the mechanism of the action of Bt Cry toxins.
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Bravo A, Likitvivatanavong S, Gill SS, Soberón M. Bacillus thuringiensis: A story of a successful bioinsecticide. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:423-31. [PMID: 21376122 PMCID: PMC3689885 DOI: 10.1016/j.ibmb.2011.02.006] [Citation(s) in RCA: 554] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 02/15/2011] [Accepted: 02/22/2011] [Indexed: 05/04/2023]
Abstract
Bacillus thuringiensis (Bt) bacteria are insect pathogens that rely on insecticidal pore forming proteins known as Cry and Cyt toxins to kill their insect larval hosts. At least four different non-structurally related families of proteins form the Cry toxin group of toxins. The expression of certain Cry toxins in transgenic crops has contributed to an efficient control of insect pests resulting in a significant reduction in chemical insecticide use. The mode of action of the three domain Cry toxin family involves sequential interaction of these toxins with several insect midgut proteins facilitating the formation of a pre-pore oligomer structure and subsequent membrane insertion that leads to the killing of midgut insect cells by osmotic shock. In this manuscript we review recent progress in understanding the mode of action of this family of proteins in lepidopteran, dipteran and coleopteran insects. Interestingly, similar Cry-binding proteins have been identified in the three insect orders, as cadherin, aminopeptidase-N and alkaline phosphatase suggesting a conserved mode of action. Also, recent data on insect responses to Cry toxin attack is discussed. Finally, we review the different Bt based products, including transgenic crops, that are currently used in agriculture.
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Affiliation(s)
- Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | | | - Sarjeet S. Gill
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico
- Corresponding author. (M. Soberón)
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Upadhyay SK, Singh PK. Role of alkaline phosphatase in insecticidal action of Cry1Ac against Helicoverpa armigera larvae. Biotechnol Lett 2011; 33:2027-36. [PMID: 21660568 DOI: 10.1007/s10529-011-0665-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 05/24/2011] [Indexed: 02/06/2023]
Abstract
Cry1Ac δ-endotoxin produced by Bacillus thuringiensis (Bt) is used as a bio-pesticide for the control of Helicoverpa armigera. Aminopeptidases N (APN) and alkaline phosphatase (ALP) play critical roles in its action against H. armigera larvae. The binding of Cry1Ac with brush border membrane vesicle (BBMV) proteins was increased with the larval development although the sensitivity of larvae to δ-endotoxins decreased. There was higher expression of ALP than APN in early instar larvae with a ~10-fold higher affinity of Cry1Ac towards ALP than to APN. Binding to a specific receptor is therefore more important for the insecticidal activity rather than overall binding to the BBMV proteins. ALP might play a major role in toxicity as compared to APN.
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Affiliation(s)
- Santosh K Upadhyay
- National Botanical Research Institute, Council of Scientific and Industrial Research, Rana Pratap Marg, Lucknow, UP 226001, India
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Likitvivatanavong S, Chen J, Evans AE, Bravo A, Soberon M, Gill SS. Multiple receptors as targets of Cry toxins in mosquitoes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:2829-38. [PMID: 21210704 PMCID: PMC3686494 DOI: 10.1021/jf1036189] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Bacillus thuringiensis (Bt) produces inclusions that are composed of proteins known as crystal proteins or Cry toxins. Due to their high specificity and their safety to humans and the environment, these Cry toxins are considered to be valuable alternatives to chemical pesticides in insect control programs. It is believed that Cry toxin-induced membrane pore formation is responsible for insect toxicity. The molecular mechanism of pore formation involves recognition and subsequent binding of the toxin to membrane receptors. This binding is accompanied by toxin oligomerization and transfer of domain I helices of the toxin to the lipid-water interface. This toxin insertion creates pores that lyse the cells. Several receptors from lepidopteran, coleopteran, and dipteran insects have been well characterized. This paper provides an overview of the understanding of the interactions between Cry toxin and multiple receptors in mosquitoes, in particular Aedes aegypti and reviews the manner by which the receptors were identified and characterized, with a focus on three proteins, cadherin, alkaline phosphatase, and aminopeptidase-N.
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Affiliation(s)
| | - Jianwu Chen
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, 92521, USA
| | - Amy E. Evans
- 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 62250, Morelos, Mexico
| | - Mario Soberon
- Instituto de Biotecnología, Universidad Nacional Autónoma de México. Apdo. postal 510-3, Cuernavaca 62250, Morelos, Mexico
| | - Sarjeet S. Gill
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA, 92521, USA
- Corresponding author: . Tel: 951-827-4621/3547
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Bulushova NV, Zhuzhikov DP, Lyutikova LI, Kirillova NE, Zalunin IA, Chestukhina GG. Toxin-binding proteins isolated from yellow mealworm Tenebrio molitor and wax moth Galleria mellonella. BIOCHEMISTRY (MOSCOW) 2011; 76:202-8. [DOI: 10.1134/s0006297911020064] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Jurat-Fuentes JL, Karumbaiah L, Jakka SRK, Ning C, Liu C, Wu K, Jackson J, Gould F, Blanco C, Portilla M, Perera O, Adang M. Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis. PLoS One 2011; 6:e17606. [PMID: 21390253 PMCID: PMC3046977 DOI: 10.1371/journal.pone.0017606] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 01/29/2011] [Indexed: 12/13/2022] Open
Abstract
Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP) as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP) were detected by two dimensional differential in-gel electrophoresis (2D-DIGE) analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR) we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.
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Affiliation(s)
- Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, United States of America.
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Dechklar M, Tiewsiri K, Angsuthanasombat C, Pootanakit K. Functional expression in insect cells of glycosylphosphatidylinositol-linked alkaline phosphatase from Aedes aegypti larval midgut: a Bacillus thuringiensis Cry4Ba toxin receptor. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:159-166. [PMID: 21146607 DOI: 10.1016/j.ibmb.2010.11.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 11/18/2010] [Accepted: 11/29/2010] [Indexed: 05/30/2023]
Abstract
Bacillus thuringiensis produces insecticidal crystal (Cry) proteins which bind to cell surface receptors on the brush border membrane of susceptible midgut larvae. The toxin-receptor interaction generates pores in midgut epithelial cells resulting in cell lysis. Here, a cDNA encoding membrane-bound alkaline phosphatase from Aedes aegypti (Aa-mALP) midgut larvae, based on the sequence identity hit to Bombyx mori membrane-bound ALP, was amplified by RT-PCR and transiently expressed in Spodoptera frugiperda (Sf9) insect cells as a 58-kDa membrane-bound protein via the baculovirus expression system and confirmed by digestion with phosphatidylinositol-specific phospholipase C and LC-MS/MS analysis. Immunolocalization results showed that Cry4Ba is able to bind to only Sf9 cells-expressing Aa-mALP. Moreover, these cells were shown to undergo cell lysis in the presence of 100 μg/ml trypsin-treated toxin. Finally, trypan blue exclusion assay also demonstrated an increase in cell death in recombinant cells treated with Cry4Ba. Overall results indicated that Aa-mALP protein was responsible for mediating Cry4Ba toxicity against Sf9 cells, suggesting its role as a receptor for Cry4Ba toxin in A. aegypti mosquito larvae.
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Affiliation(s)
- Manasave Dechklar
- Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand
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Cadherin, alkaline phosphatase, and aminopeptidase N as receptors of Cry11Ba toxin from Bacillus thuringiensis subsp. jegathesan in Aedes aegypti. Appl Environ Microbiol 2010; 77:24-31. [PMID: 21037295 DOI: 10.1128/aem.01852-10] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cry11Ba is one of the most toxic proteins to mosquito larvae produced by Bacillus thuringiensis. It binds Aedes aegypti brush border membrane vesicles (BBMV) with high affinity, showing an apparent dissociation constant (K(d)) of 8.2 nM. We previously reported that an anticadherin antibody competes with Cry11Ba binding to BBMV, suggesting a possible role of cadherin as a toxin receptor. Here we provide evidence of specific cadherin repeat regions involved in this interaction. Using cadherin fragments as competitors, a C-terminal fragment which contains cadherin repeat 7 (CR7) to CR11 competed with Cry11Ba binding to BBMV. This binding was also efficiently competed by the CR9, CR10, and CR11 peptide fragments. Moreover, we show CR11 to be an important region of interaction with Cry11Ba toxin. An alkaline phosphatase (AaeALP1) and an aminopeptidase-N (AaeAPN1) also competed with Cry11Ba binding to Ae. aegypti BBMV. Finally, we found that Cry11Ba and Cry4Ba share binding sites. Synthetic peptides corresponding to loops α8, β2-β3 (loop 1), β8-β9, and β10-β11 (loop 3) of Cry4Ba compete with Cry11Ba binding to BBMV, suggesting Cry11Ba and Cry4Ba have common sites involved in binding Ae. aegypti BBMV. The data suggest that three different Ae. aegypti midgut proteins, i.e., cadherin, AaeALP1, and AaeAPN1, are involved in Cry11Ba binding to Ae. aegypti midgut brush border membranes.
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Ning C, Wu K, Liu C, Gao Y, Jurat-Fuentes JL, Gao X. Characterization of a Cry1Ac toxin-binding alkaline phosphatase in the midgut from Helicoverpa armigera (Hübner) larvae. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:666-672. [PMID: 20170658 DOI: 10.1016/j.jinsphys.2010.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 02/05/2010] [Accepted: 02/08/2010] [Indexed: 05/28/2023]
Abstract
Midgut membrane-bound alkaline phosphatases (mALP) tethered to the brush border membrane surface by a glycosylphosphatidylinositol (GPI) anchor have been proposed as crucial for Cry1Ac intoxication. In the present work, two full-length cDNAs-encoding alkaline phosphatases in the midgut of Helicoverpa armigera larvae were cloned and named HaALP1 (GenBank accession no. EU729322) and HaALP2 (GenBank accession no. EU729323), respectively. These two clones displayed high identity (above 94%) at the amino acid sequence, indicating that they may represent allelic variants, and were predicted to contain a GPI anchor. Protein sequence alignment revealed that HaALPs were grouped with mALP from the Heliothis virescens midgut. The HaALP1 and HaALP2 ( approximately 68kDa) proteins were heterologously expressed in Sf9 cells using a baculovirus expression system and purified to homogeneity. Ligand blot and dot blot analysis revealed that the Cry1Ac bound to both denatured and native purified HaALPs. Data from lectin blots, competition assays with soybean agglutinin (SBA) lectin and GalNAc binding inhibition assays were indicative of the presence of GalNAc on HaALPs and binding of Cry1Ac toxin to this residue. This observation was further confirmed through N-glycosidase digestion of HaALPs, which resulted in reduced Cry1Ac binding. Our data represent the first report on HaALPs and their putative role as receptors for Cry1Ac toxin in H. armigera.
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Affiliation(s)
- Changming Ning
- State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Enhancing Cry1Ac toxicity by expression of the Helicoverpa armigera cadherin fragment in Bacillus thuringiensis. Res Microbiol 2010; 161:383-9. [PMID: 20438837 DOI: 10.1016/j.resmic.2010.04.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 04/08/2010] [Accepted: 04/15/2010] [Indexed: 01/14/2023]
Abstract
Insect cadherin proteins localized in the midgut epithelium were identified as receptors for Bacillus thuringiensis insecticidal crystal proteins (Cry toxins). These cadherins facilitated toxin monomer oligomerization and mediated oligomer binding to secondary receptors. It has been reported that Manduca sexta, Helicoverpa armigera, Anopheles gambiae and Diabrotica virgifera cadherin toxin binding regions function as synergists for Cry1A, Cry4Ba and Cry3A toxicity against target insects. In the present study, the toxin binding region fragment of the H. armigera cadherin (hacad1) gene was cloned and fused with the promoter of the cry3Aa gene. The fusion gene pro3Aa-hacad1 and the cry1Ac gene were inserted into shuttle vector pHT304 and introduced into B. thuringiensis acrystalliferous strain BMB171 for coexpression (resulting in recombinant strain BMB1073). SDS-PAGE and mass spectrum analysis showed that BMB1073 could express HaCad1 and Cry1Ac proteins together. Bioassay results demonstrated that insecticidal activities against H. armigera and Spodoptera exigua could be increased 5.1-fold and 6.5-fold, respectively, by BMB1073 compared with the strain which can only express the Cry1Ac protein. Our discovery showed that coexpression of HaCad1 and Cry1Ac toxin in B. thuringiensis enhanced the insecticidal activity of Cry1Ac toward Lepidoptera insects. This finding also revealed a novel strategy for engineering strains and transgenic plants with higher insecticidal activity.
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