1
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Chen Z, Shi Y, Wang D, Liu X, Jiao X, Gao X, Jiang K. Structural insight into Bacillus thuringiensis Sip1Ab reveals its similarity to ETX_MTX2 family beta-pore-forming toxin. PEST MANAGEMENT SCIENCE 2023; 79:4264-4273. [PMID: 37341620 DOI: 10.1002/ps.7622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 06/15/2023] [Accepted: 06/21/2023] [Indexed: 06/22/2023]
Abstract
BACKGROUND Microbially derived, protein-based biopesticides are an important approach for sustainable pest management. The secreted insecticidal proteins (Sips) produced by the bacterium Bacillus thuringiensis exhibit potent insecticidal activity against coleopteran pests and are, therefore, attractive as candidate biopesticides. However, the modes-of-action of Sips are unclear as comprehensive structural information for these proteins is lacking. RESULTS Using X-ray crystallography, we elucidated the structure of monomeric Sip1Ab at 2.28 Å resolution. Structural analyses revealed that Sip1Ab has the three domains and conserved fold characteristic of other aerolysin-like beta-pore-forming toxins (β-PFTs). Based on the sequence and structural similarities between Sip1Ab and other ETX_MTX2 subfamily toxins, we suggested the mechanism of these proteins and proposed that it is common to them all. CONCLUSION The atomic-level structural data for Sip1Ab generated by the present study could facilitate future structural and mechanistic research on Sips as well as their application in sustainable insect pest management. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Zhe Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yiting Shi
- Taishan College, Shandong University, Jinan, China
| | - Dongdong Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xiaoyu Liu
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Xuyao Jiao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xiang Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Kun Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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2
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Pacheco S, Gómez I, Peláez-Aguilar AE, Verduzco-Rosas LA, García-Suárez R, do Nascimento NA, Rivera-Nájera LY, Cantón PE, Soberón M, Bravo A. Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis. FRONTIERS IN INSECT SCIENCE 2023; 3:1188891. [PMID: 38469496 PMCID: PMC10926538 DOI: 10.3389/finsc.2023.1188891] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 04/04/2023] [Indexed: 03/13/2024]
Abstract
Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some of these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism of action of these toxins that have helped to improve their performance and to cope with the resistance evolved by different insects against some of these proteins. However, crucial information that is still missing is the structure of pores formed by some of these PFTs, such as the three-domain crystal (Cry) proteins, which are the most commercially used Bt toxins in the biological control of insect pests. In recent years, progress has been made on the identification of the structural changes that certain Bt insecticidal PFT proteins undergo upon membrane insertion. In this review, we describe the models that have been proposed for the membrane insertion of Cry toxins. We also review the recently published structures of the vegetative insecticidal proteins (Vips; e.g. Vip3) and the insecticidal toxin complex (Tc) in the membrane-inserted state. Although different Bt PFTs show different primary sequences, there are some similarities in the three-dimensional structures of Vips and Cry proteins. In addition, all PFTs described here must undergo major structural rearrangements to pass from a soluble form to a membrane-inserted state. It is proposed that, despite their structural differences, all PFTs undergo major structural rearrangements producing an extended α-helix, which plays a fundamental role in perforating their target membrane, resulting in the formation of the membrane pore required for their insecticidal activity.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
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3
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Jiang K, Chen Z, Zang Y, Shi Y, Shang C, Jiao X, Cai J, Gao X. Functional characterization of Vip3Aa from Bacillus thuringiensis reveals the contributions of specific domains to its insecticidal activity. J Biol Chem 2023; 299:103000. [PMID: 36764522 PMCID: PMC10017365 DOI: 10.1016/j.jbc.2023.103000] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
Microbially derived, protein-based biopesticides offer a more sustainable pest management alternative to synthetic pesticides. Vegetative insecticidal proteins (Vip3), multidomain proteins secreted by Bacillus thuringiensis, represent a second-generation insecticidal toxin that has been preliminarily used in transgenic crops. However, the molecular mechanism underlying Vip3's toxicity is poorly understood. Here, we determine the distinct functions and contributions of the domains of the Vip3Aa protein to its toxicity against Spodoptera frugiperda larvae. We demonstrate that Vip3Aa domains II and III (DII-DIII) bind the midgut epithelium, while DI is essential for Vip3Aa's stability and toxicity inside the protease-enriched host insect midgut. DI-DIII can be activated by midgut proteases and exhibits cytotoxicity similar to full-length Vip3Aa. In addition, we determine that DV can bind the peritrophic matrix via its glycan-binding activity, which contributes to Vip3Aa insecticidal activity. In summary, this study provides multiple insights into Vip3Aa's mode-of-action which should significantly facilitate the clarification of its insecticidal mechanism and its further rational development.
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Affiliation(s)
- Kun Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Zhe Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yuanrong Zang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yiting Shi
- School of Life Sciences, Shandong University, Qingdao, China; Taishan College, Shandong University, Jinan, China
| | - Chengbin Shang
- School of Life Sciences, Shandong University, Qingdao, China
| | - Xuyao Jiao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jun Cai
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiang Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
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4
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Fu BW, Xu L, Zheng MX, Chen QX, Shi Y, Zhu YJ. Stability is essential for insecticidal activity of Vip3Aa toxin against Spodoptera exigua. AMB Express 2022; 12:92. [PMID: 35834019 PMCID: PMC9283630 DOI: 10.1186/s13568-022-01430-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 07/02/2022] [Indexed: 11/10/2022] Open
Abstract
Vegetative insecticidal proteins 3A (Vip3A) were important insecticidal proteins for control of lepidopteran pests. Previous study demonstrated that Vip3Aa and Vip3Ad showed significant difference in insecticidal activities against Spodoptera exigua, while the molecular mechanism remained ambiguous. Here we demonstrated that the difference in insecticidal activities between Vip3Aa and Vip3Ad might be caused by the difference in stability of Vip3Aa and Vip3Ad in S. exigua midgut protease. Vip3Aa was quite stable while Vip3Ad could be further degraded. Molecular dynamics simulation revealed that Vip3Aa was more stable than Vip3Ad, with smaller RMSD and RMSF value. Amino acid sequence alignment indicated that three were three extra prolines (P591, P605 and P779) located on Vip3Aa. We further identified that residue P591 played a crucial role on stability and insecticidal activity of Vip3Aa. Taken together, our study demonstrated that the stability was essential for the insecticidal activity of Vip3A toxins, which might provide new insight into the action mode of Vip3A toxins and contribute to the design Vip3A variants with improved stability and insecticidal activity.
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Affiliation(s)
- Bai-Wen Fu
- School of Life Sciences, Xiamen University, Xiamen, 361005, China
| | - Lian Xu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China
| | - Mei-Xia Zheng
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China
| | - Qing-Xi Chen
- School of Life Sciences, Xiamen University, Xiamen, 361005, China
| | - Yan Shi
- School of Life Sciences, Xiamen University, Xiamen, 361005, China.
| | - Yu-Jing Zhu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.
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5
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Lázaro-Berenguer M, Paredes-Martínez F, Bel Y, Núñez-Ramírez R, Arias-Palomo E, Casino P, Ferré J. Structural and functional role of Domain I for the insecticidal activity of the Vip3Aa protein from Bacillus thuringiensis. Microb Biotechnol 2022; 15:2607-2618. [PMID: 35830334 PMCID: PMC9518980 DOI: 10.1111/1751-7915.14110] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 06/07/2022] [Accepted: 06/13/2022] [Indexed: 12/05/2022] Open
Abstract
Vip3 proteins are produced by Bacillus thuringiensis and are toxic against lepidopterans, reason why the vip3Aa gene has been introduced into cotton and corn to control agricultural pests. Recently, the structure of Vip3 proteins has been determined and consists of a tetramer where each monomer is composed of five structural domains. The transition from protoxin to the trypsin‐activated form involves a major conformational change of the N‐terminal Domain I, which is remodelled into a tetrameric coiled‐coil structure that is thought to insert into the apical membrane of the midgut cells. To better understand the relevance of this major change in Domain I for the insecticidal activity, we have generated several mutants aimed to alter the activity and remodelling capacity of this central region to understand its function. These mutants have been characterized by proteolytic processing, negative staining electron microscopy, and toxicity bioassays against Spodoptera exigua. The results show the crucial role of helix α1 for the insecticidal activity and in restraining the Domain I in the protoxin conformation, the importance of the remodelling of helices α2 and α3, the proteolytic processing that takes place between Domains I and II, and the role of the C‐t Domains IV and V to sustain the conformational change necessary for toxicity.
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Affiliation(s)
- Maria Lázaro-Berenguer
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
| | - Francisco Paredes-Martínez
- Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain.,Department of Biochemistry and Molecular Biology, Universitat de València, Burjassot, Spain
| | - Yolanda Bel
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
| | | | | | - Patricia Casino
- Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain.,Department of Biochemistry and Molecular Biology, Universitat de València, Burjassot, Spain.,CIBER de Enfermedades Raras (CIBERER-ISCIII), Madrid, Spain
| | - Juan Ferré
- Department of Genetics, Universitat de València, Burjassot, Spain.,Institut Universitari de Biotecnologia i Biomedicina BIOTECMED, Universitat de València, Burjassot, Spain
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6
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Zhang Y, Li X, Tian H, An B, Yan B, Cai J. Vegetative Insecticidal Protein Vip3Aa Is Transported via Membrane Vesicles in Bacillus thuringiensis BMB171. Toxins (Basel) 2022; 14:toxins14070480. [PMID: 35878218 PMCID: PMC9319297 DOI: 10.3390/toxins14070480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/10/2022] [Accepted: 07/11/2022] [Indexed: 11/16/2022] Open
Abstract
Vegetative insecticidal protein Vip3Aa, secreted by many Bacillus thuringiensis (Bt) strains during the vegetative growth stage, represents the second-generation insecticidal toxin. In recent years, significant progress has been made on its structure and action mechanism. However, how it is translocated across the cytoplasmic membrane into the environment remains a mystery. This work demonstrates that Vip3Aa is not secreted by the General Secretion (Sec) System. To reveal the secretory pathway of Vip3A, we purified the membrane vesicles (MVs) of B. thuringiensis BMB171 and observed by TEM. The size of MVs was determined by the dynamic light scattering method, and their diameter was approximately 40–200 nm, which is consistent with the vesicles in Gram-negative bacteria. Moreover, Vip3A could be detected in the purified MVs by Western blot, and immunoelectron microscopy reveals Vip3A antibody-coated gold particles located in the MVs. After deleting its signal peptide, chitinase B (ChiB) failed to be secreted. However, the recombinant ChiB, whose signal peptide was substituted with the N-terminal 39 amino acids from Vip3A, was secreted successfully through MVs. Thus, this sequence is proposed as the signal region responsible for vesicle transport. Together, our results revealed for the first time that Vip3Aa is transported to the medium via MVs.
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Affiliation(s)
- Yizhuo Zhang
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
| | - Xuelian Li
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
| | - Hongwei Tian
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
| | - Baoju An
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
| | - Bing Yan
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
| | - Jun Cai
- Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China; (Y.Z.); (X.L.); (H.T.); (B.A.); (B.Y.)
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, Tianjin 300071, China
- Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin 300071, China
- Correspondence:
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7
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Singh P, G. K. S, Thakur S, Rathore M, Verma OP, Singh NP, Das A. Evaluation of transgenic chickpea harboring codon-modified Vip3Aa against gram pod borer (Helicoverpa armigera H.). PLoS One 2022; 17:e0270011. [PMID: 35749522 PMCID: PMC9231776 DOI: 10.1371/journal.pone.0270011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 06/01/2022] [Indexed: 11/29/2022] Open
Abstract
The gram pod borer is a major pest of chickpea, accounting for average annual yield losses to the tune of 40-50%. VIP3Aa, a class of insecticidal protein with different receptor binding site in the insect's midgut compared to Bt-crystal protein, offers an alternative protection strategy against Lepidopteran insects. Here, we report evaluation of genetically engineered chickpea lines harboring codon modified Vip3Aa (cmVip3Aa) against the Lepidopteran insect pest, gram pod borer. The synthetic codon modified, cmVip3Aa gene of 2,370 bp was sub-cloned in modified plant expression vector and used for direct transformation of embryonic axis explants of chickpea (cv. DCP 92-3), with transformation efficiency of 4.30%. Presence and transmission of transgene across two generations were confirmed by PCR and Southern blot analyses in the five selected transgenic chickpea lines. Real Time PCR analyses indicated variable levels of cmVip3Aa expression in the transgenic chickpea lines (average Cq values 15.01±0.86 to 19.32±0.10), which were absent in the non-transgenic counterpart. Detached leaf insect bioassay indicate larval mortality (up to 39.75%), reduced larval feeding (up to 82.91%) and reduced larval weight gain (up to 68.23%), compared to control lines. Evaluation of gene offers a platform to identify efficacious insecticidal gene that can be used for insect resistance management in chickpea.
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Affiliation(s)
- Prateek Singh
- Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
- Department of Molecular and Cellular Engineering, Jacob Institute of Biotechnology and Bioengineering, SHUATS, Prayagraj, Uttar Pradesh, India
| | - Sujayanand G. K.
- Division of Crop Protection, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
| | - Shallu Thakur
- Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
| | - Meenal Rathore
- Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
| | - Om Prakash Verma
- Department of Molecular and Cellular Engineering, Jacob Institute of Biotechnology and Bioengineering, SHUATS, Prayagraj, Uttar Pradesh, India
| | - Narendra Pratap Singh
- Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
| | - Alok Das
- Division of Plant Biotechnology, ICAR-Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India
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8
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Yang X, Wang Z, Geng L, Chi B, Liu R, Li H, Gao J, Zhang J. Vip3Aa domain IV and V mutants confer higher insecticidal activity against Spodoptera frugiperda and Helicoverpa armigera. PEST MANAGEMENT SCIENCE 2022; 78:2324-2331. [PMID: 35243758 DOI: 10.1002/ps.6858] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/23/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
BACKGROUND The fall armyworm Spodoptera frugiperda and cotton bollworm Helicoverpa armigera are major insect pests of corn and cotton worldwide. Genetically engineered crops producing Vip3Aa, a potent endotoxin, from the bacterium Bacillus thuringiensis (Bt) are effective in controlling these two harmful pests. However, Vip3Aa efficacy is relatively weak compared to that of other Bt proteins such as Cry1A and Cry1F. This study sought to modify Vip3Aa for increased insecticidal activity and determine the cause of elevated activity. RESULTS The two triple Vip3Aa mutants in domains IV and V (Vip3Aa-S543N/I544L/E627A and Vip3Aa-S543N/I544L/S686R) exhibited 7.3-fold and 2.8-fold increased toxicity against S. frugiperda, respectively, compared with the wild type while the toxicity of Vip3Aa-S543N/I544L/S686R was 3.2 times that of wild-type protein in H. armigera. The mutants had enhanced stability in midgut juice and 2.6-5.1 times higher binding affinity against S. frugiperda and H. armigera compared with wild type protein. CONCLUSIONS The enhanced toxicity of Vip3Aa mutants was due to increased stability and binding affinity during infection. The amino acids S543 and I544 combined with E627 or S686 in domains IV and V of Vip3Aa are important for maintaining structural stability and receptor binding. The results match insecticidal activity (LC50 ) with binding activity (Kd ), which provides novel clues for the rational design of Bt insecticidal proteins. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Xiaoxue Yang
- Northeast Agricultural University, Harbin, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zeyu Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Lili Geng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Baoyan Chi
- Northeast Agricultural University, Harbin, China
| | - Rongmei Liu
- Northeast Agricultural University, Harbin, China
| | - Haitao Li
- Northeast Agricultural University, Harbin, China
| | - Jiguo Gao
- Northeast Agricultural University, Harbin, China
| | - Jie Zhang
- Northeast Agricultural University, Harbin, China
- 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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9
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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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10
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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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11
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Gupta M, Kumar H, Kaur S. Vegetative Insecticidal Protein (Vip): A Potential Contender From Bacillus thuringiensis for Efficient Management of Various Detrimental Agricultural Pests. Front Microbiol 2021; 12:659736. [PMID: 34054756 PMCID: PMC8158940 DOI: 10.3389/fmicb.2021.659736] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/19/2021] [Indexed: 11/25/2022] Open
Abstract
Bacillus thuringiensis (Bt) bacterium is found in various ecological habitats, and has natural entomo-pesticidal properties, due to the production of crystalline and soluble proteins during different growth phases. In addition to Cry and Cyt proteins, this bacterium also produces Vegetative insecticidal protein (Vip) during its vegetative growth phase, which is considered an excellent toxic candidate because of the difference in sequence homology and receptor sites from Cry proteins. Vip proteins are referred as second-generation insecticidal proteins, which can be used either alone or in complementarity with Cry proteins for the management of various detrimental pests. Among these Vip proteins, Vip1 and Vip2 act as binary toxins and have toxicity toward pests belonging to Hemiptera and Coleoptera orders, whereas the most important Vip3 proteins have insecticidal activity against Lepidopteran pests. These Vip3 proteins are similar to Cry proteins in terms of toxicity potential against susceptible insects. They are reported to be toxic toward pests, which can’t be controlled with Cry proteins. The Vip3 proteins have been successfully pyramided along with Cry proteins in transgenic rice, corn, and cotton to combat resistant pest populations. This review provides detailed information about the history and importance of Vip proteins, their types, structure, newly identified specific receptors, and action mechanism of this specific class of proteins. Various studies conducted on Vip proteins all over the world and the current status have been discussed. This review will give insights into the significance of Vip proteins as alternative promising candidate toxic proteins from Bt for the management of pests in most sustainable manner.
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Affiliation(s)
- Mamta Gupta
- ICAR-National Institute for Plant Biotechnology, New Delhi, India.,ICAR-Indian Institute of Maize Research, Ludhiana, India
| | - Harish Kumar
- Punjab Agricultural University, Regional Research Station, Faridkot, India
| | - Sarvjeet Kaur
- ICAR-National Institute for Plant Biotechnology, New Delhi, India
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12
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Bacillus thuringiensis Toxins: Functional Characterization and Mechanism of Action. Toxins (Basel) 2020; 12:toxins12120785. [PMID: 33321796 PMCID: PMC7763903 DOI: 10.3390/toxins12120785] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/06/2020] [Accepted: 12/08/2020] [Indexed: 11/16/2022] Open
Abstract
Bacillus thuringiensis (Bt)-based products are the most successful microbial insecticides to date [...].
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13
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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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