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Meng M, Shen C, Lin M, Jin J, Chen W, Zhang X, Xu C, Hu X, Zhu Q, Chen C, Xie Y, Jacob Pooe O, Crickmore N, Liu X, Lü P, Liu Y. Characterization of the individual domains of the Bacillus thuringiensis Cry2Aa implicates Domain I as a possible binding site to Helicoverpa armigera. J Invertebr Pathol 2024; 205:108129. [PMID: 38754546 DOI: 10.1016/j.jip.2024.108129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/18/2024]
Abstract
Bacillus thuringiensis (Bt) Cry2Aa is a member of the Cry pore-forming, 3-domain, toxin family with activity against both lepidopteran and dipteran insects. Although domains II and III of the Cry toxins are believed to represent the primary specificity determinant through specific binding to cell receptors, it has been proposed that the pore-forming domain I of Cry2Aa also has such a role. Thus, a greater understanding of the functions of Cry2Aa's different domains could potentially be helpful in the rational design of improved toxins. In this work, cry2Aa and its domain fragments (DI, DII, DIII, DI-II and DII-DIII) were subcloned into the vector pGEX-6P-1 and expressed in Escherichia coli. Each protein was recognized by anti-Cry2Aa antibodies and, except for the DII fragment, could block binding of the antibody to Cry2Aa. Cry2Aa and its DI and DI-II fragments bound to brush border membrane vesicles (BBMV) from H. armigera and also to a ca 150 kDa BBMV protein on a far western (ligand) blot. In contrast the DII, DIII and DII-III fragments bound to neither of these. None of the fragments were stable in H. armigera gut juice nor showed any toxicity towards this insect. Our results indicate that contrary to the general model of Cry toxin activity domain I plays a role in the binding of the toxin to the insect midgut.
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Affiliation(s)
- Meng Meng
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Cheng Shen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Manman Lin
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Jiafeng Jin
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Wei Chen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Xiao Zhang
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Chongxin Xu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Xiaodan Hu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Qing Zhu
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Chengyu Chen
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Yajing Xie
- Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Ofentse Jacob Pooe
- School of Life Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
| | - Neil Crickmore
- School of Biological Sciences, University of Sussex, Brighton BN1 9RH, United Kingdom
| | - Xianjin Liu
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China
| | - Peng Lü
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China.
| | - Yuan Liu
- School of Life Sciences, Jiangsu University, Zhenjiang 212013, China; Key Laboratory of Food Quality and Safety of Jiangsu Province, Nanjing 210014, China.
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Jiang K, Gao X. Current advances on Vip3 highlight the promising potential of bacterial insecticidal proteins. Trends Microbiol 2024:S0966-842X(24)00145-8. [PMID: 38902178 DOI: 10.1016/j.tim.2024.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 06/22/2024]
Abstract
Biological control, based on microbial insecticidal proteins, has become an important strategy for sustainable pest management. This forum discusses recent advancements and research strategies of the bacterial insecticidal protein vegetative insecticidal protein 3 (Vip3), aiming to provide valuable insights for future investigations on Vip3 and other insecticidal proteins.
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Affiliation(s)
- Kun Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
| | - Xiang Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China.
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3
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Ma T, Huang J, Xu P, Shu C, Wang Z, Geng L, Zhang J. In Vivo and In Vitro Interactions between Exopolysaccharides from Bacillus thuringensis HD270 and Vip3Aa11 Protein. Toxins (Basel) 2024; 16:215. [PMID: 38787067 PMCID: PMC11125869 DOI: 10.3390/toxins16050215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 04/29/2024] [Accepted: 05/01/2024] [Indexed: 05/25/2024] Open
Abstract
Bacillus thuringiensis (Bt) secretes the nutritional insecticidal protein Vip3Aa11, which exhibits high toxicity against the fall armyworm (Spodoptera frugiperda). The Bt HD270 extracellular polysaccharide (EPS) enhances the toxicity of Vip3Aa11 protoxin against S. frugiperda by enhancing the attachment of brush border membrane vesicles (BBMVs). However, how EPS-HD270 interacts with Vip3Aa11 protoxin in vivo and the effect of EPS-HD270 on the toxicity of activated Vip3Aa11 toxin are not yet clear. Our results indicated that there is an interaction between mannose, a monosaccharide that composes EPS-HD270, and Vip3Aa11 protoxin, with a dissociation constant of Kd = 16.75 ± 0.95 mmol/L. When EPS-HD270 and Vip3Aa11 protoxin were simultaneously fed to third-instar larvae, laser confocal microscopy observations revealed the co-localization of the two compounds near the midgut wall, which aggravated the damage to BBMVs. EPS-HD270 did not have a synergistic insecticidal effect on the activated Vip3Aa11 protein against S. frugiperda. The activated Vip3Aa11 toxin demonstrated a significantly reduced binding capacity (548.73 ± 82.87 nmol/L) towards EPS-HD270 in comparison to the protoxin (34.96 ± 9.00 nmol/L). Furthermore, this activation diminished the affinity of EPS-HD270 for BBMVs. This study provides important evidence for further elucidating the synergistic insecticidal mechanism between extracellular polysaccharides and Vip3Aa11 protein both in vivo and in vitro.
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Affiliation(s)
- Tianjiao Ma
- College of Life Sciences, Northeast Agricultural University, Harbin 150030, China; (T.M.); (J.H.)
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jinqiu Huang
- College of Life Sciences, Northeast Agricultural University, Harbin 150030, China; (T.M.); (J.H.)
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Pengdan Xu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- College of Plant Protection, Anhui Agricultural University, Hefei 230036, China
| | - Changlong Shu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zeyu Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Lili Geng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Jie Zhang
- College of Life Sciences, Northeast Agricultural University, Harbin 150030, China; (T.M.); (J.H.)
- 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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Jiang K, Li W, Tong M, Xu J, Chen Z, Yang Y, Zang Y, Jiao X, Liu C, Lim B, Jiang X, Wang J, Wu D, Wang M, Liu SJ, Shao F, Gao X. Bacteroides fragilis ubiquitin homologue drives intraspecies bacterial competition in the gut microbiome. Nat Microbiol 2024; 9:70-84. [PMID: 38082149 DOI: 10.1038/s41564-023-01541-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 10/26/2023] [Indexed: 12/21/2023]
Abstract
Interbacterial antagonism and associated defensive strategies are both essential during bacterial competition. The human gut symbiont Bacteroides fragilis secretes a ubiquitin homologue (BfUbb) that is toxic to a subset of B. fragilis strains in vitro. In the present study, we demonstrate that BfUbb lyses certain B. fragilis strains by non-covalently binding and inactivating an essential peptidyl-prolyl isomerase (PPIase). BfUbb-sensitivity profiling of B. fragilis strains revealed a key tyrosine residue (Tyr119) in the PPIase and strains that encode a glutamic acid residue at Tyr119 are resistant to BfUbb. Crystal structural analysis and functional studies of BfUbb and the BfUbb-PPIase complex uncover a unique disulfide bond at the carboxy terminus of BfUbb to mediate the interaction with Tyr119 of the PPIase. In vitro coculture assays and mouse studies show that BfUbb confers a competitive advantage for encoding strains and this is further supported by human gut metagenome analyses. Our findings reveal a previously undescribed mechanism of bacterial intraspecies competition.
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Affiliation(s)
- Kun Jiang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Weixun Li
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ming Tong
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jinghua Xu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Zhe Chen
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yan Yang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yuanrong Zang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xuyao Jiao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Chang Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Bentley Lim
- Department of Microbial Pathogenesis and Microbial Sciences Institute, Yale University School of Medicine, New Haven, CT, USA
| | - Xianzhi Jiang
- Microbiome Research Center, Moon (Guangzhou) Biotech Co. Ltd., Guangzhou, China
| | - Jiawei Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China
| | - Dalei Wu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Mingyu Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Feng Shao
- National Institute of Biological Sciences, Beijing, China
| | - Xiang Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
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Hou X, Li M, Mao C, Jiang L, Zhang W, Li M, Geng X, Li X, Liu S, Yang G, Zhou J, Fang Y, Cai J. Domain III β4- β5 Loop and β14- β15 Loop of Bacillus thuringiensis Vip3Aa Are Involved in Receptor Binding and Toxicity. Toxins (Basel) 2024; 16:23. [PMID: 38251240 PMCID: PMC10820090 DOI: 10.3390/toxins16010023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/23/2023] [Accepted: 12/30/2023] [Indexed: 01/23/2024] Open
Abstract
Vip3Aa, secreted by Bacillus thuringiensis, is effective at controlling major agricultural pests such as Spodoptera frugiperda. However, to control Vip3Aa resistance evolved in the field by different lepidoptera species, an in-depth study of sequence--structure--activity relationships is necessary to design new Vip3Aa variants. In this study, the four specific loops (β4-β5 loop, β9-β10 loop, β12-β13 loop, and β14-β15 loop) in domain III were selected and four loop mutants were constructed by replacing all residues in each specific loop with alanine. We obtained soluble proteins for three of the loop mutants, excluding the β9-β10 loop. These loop mutants have been characterized by toxicity bioassays against S. frugiperda, proteolytic processing, and receptor binding. These results indicate that the β4-β5 loop and β14-β15 loop are involved in receptor binding and Vip3Aa toxicity. Based on this, we constructed numerous mutants and obtained three single mutants (Vip3Aa-S366T, Vip3Aa-S366L, and Vip3Aa-R501A) that exhibited significantly increased toxicity of 2.61-fold, 3.39-fold, and 2.51-fold, respectively. Compared to Vip3Aa, the receptor affinity of Vip3Aa-S366T and Vip3Aa-S366L was significantly enhanced. Furthermore, we also analyzed and aligned the three-dimensional structures of the mutants and Vip3Aa. In summary, these results indicate that the loops in domain III have the potential to be targeted to enhance the insecticidal toxicity of the Vip3Aa protein.
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Affiliation(s)
- Xiaoyue Hou
- Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang 222005, China; (X.H.); (S.L.); (G.Y.)
- Co–Innovation Center of Jiangsu Marine Bio–Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222005, China
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
- College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Mengjiao Li
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Chengjuan Mao
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Lei Jiang
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Wen Zhang
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Mengying Li
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Xiaomeng Geng
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Xin Li
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Shu Liu
- Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang 222005, China; (X.H.); (S.L.); (G.Y.)
- Co–Innovation Center of Jiangsu Marine Bio–Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222005, China
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Guang Yang
- Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang 222005, China; (X.H.); (S.L.); (G.Y.)
- Co–Innovation Center of Jiangsu Marine Bio–Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222005, China
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Jing Zhou
- Lianyungang City Quality Technology Comprehensive Inspection and Quality Inspection Center, Lianyungang 222346, China;
| | - Yaowei Fang
- Jiangsu Key Laboratory of Marine Bioresources and Environment, Jiangsu Ocean University, Lianyungang 222005, China; (X.H.); (S.L.); (G.Y.)
- Co–Innovation Center of Jiangsu Marine Bio–Industry Technology, Jiangsu Ocean University, Lianyungang 222005, China
- Jiangsu Marine Resources Development Research Institute, Jiangsu Ocean University, Lianyungang 222005, China
- College of Marine Food and Bioengineering, Jiangsu Ocean University, Lianyungang 222005, China; (M.L.); (C.M.); (L.J.); (W.Z.); (M.L.); (X.G.); (X.L.)
| | - Jun Cai
- College of Life Sciences, Nankai University, Tianjin 300071, China
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6
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Gouda MNR, Jeevan H, Shashank HG. CRISPR/Cas9: a cutting-edge solution for combatting the fall armyworm, Spodoptera frugiperda. Mol Biol Rep 2023; 51:13. [PMID: 38085335 DOI: 10.1007/s11033-023-08986-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 10/13/2023] [Indexed: 12/18/2023]
Abstract
The utilization of CRISPR/Cas9 in Spodoptera frugiperda, commonly known as fall armyworm, presents a groundbreaking avenue for pest management. With its ability to precisely modify the insect's genome, CRISPR/Cas9 offers innovative strategies to combat this destructive pest. The application of CRISPR/Cas9 in S. frugiperda holds immense potential. It enables the identification and functional analysis of key genes associated with its behavior, development, and insecticide resistance. This knowledge can unveil novel target sites for more effective and specific insecticides. Additionally, CRISPR/Cas9 can facilitate the development of population control methods by disrupting vital genes essential for survival. However, challenges such as off-target effects and the efficient delivery of CRISPR/Cas9 components remain. Addressing these obstacles is vital to ensure accurate and reliable results. Furthermore, ethical considerations, biosafety protocols, and regulatory frameworks must be integral to the adoption of this technology. Looking forward, CRISPR/Cas9-based gene drive systems hold the potential to promulgate desirable genetic traits within S. frugiperda populations, offering a sustainable and eco-friendly approach. This could curtail their reproductive capabilities or make them more susceptible to certain interventions. In conclusion, CRISPR/Cas9 presents a transformative platform for precise and targeted pest management in S. frugiperda. By deciphering the insect's genetic makeup and developing innovative strategies, we can mitigate the devastating impact of fall armyworm on agriculture while ensuring environmental sustainability.
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Affiliation(s)
- M N Rudra Gouda
- Division of Entomology, Indian Agricultural Research Institute, New Delhi, 110012, India.
| | - H Jeevan
- Division of Nematology, Indian Agricultural Research Institute, New Delhi, 110012, India
| | - H G Shashank
- Division of Plant Genetic Resources, Indian Agricultural Research Institute, New Delhi, 110012, India
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7
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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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8
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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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