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Wang HC, Lin SJ, Wang HC, Kumar R, Le PT, Leu JH. A bacterial binary toxin system that kills both insects and aquatic crustaceans: Photorhabdus insect-related toxins A and B. PLoS Pathog 2023; 19:e1011330. [PMID: 37141203 PMCID: PMC10159206 DOI: 10.1371/journal.ppat.1011330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
Abstract
Photorhabdus insect-related toxins A and B (PirA and PirB) were first recognized as insecticidal toxins from Photorhabdus luminescens. However, subsequent studies showed that their homologs from Vibrio parahaemolyticus also play critical roles in the pathogenesis of acute hepatopancreatic necrosis disease (AHPND) in shrimps. Based on the structural features of the PirA/PirB toxins, it was suggested that they might function in the same way as a Bacillus thuringiensis Cry pore-forming toxin. However, unlike Cry toxins, studies on the PirA/PirB toxins are still scarce, and their cytotoxic mechanism remains to be clarified. In this review, based on our studies of V. parahaemolyticus PirAvp/PirBvp, we summarize the current understanding of the gene locations, expression control, activation, and cytotoxic mechanism of this type of toxin. Given the important role these toxins play in aquatic disease and their potential use in pest control applications, we also suggest further topics for research. We hope the information presented here will be helpful for future PirA/PirB studies.
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Affiliation(s)
- Hao-Ching Wang
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, Republic of China
- The PhD Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei, Taiwan, Republic of China
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Shin-Jen Lin
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Han-Ching Wang
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Ramya Kumar
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan, Republic of China
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Phuoc Thien Le
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, Republic of China
| | - Jiann-Horng Leu
- Institute of Marine Biology, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
- Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
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Lei X, Zhang F, Zhang J. Gut Microbiota Accelerate the Insecticidal Activity of Plastid-Expressed Bacillus thuringiensis Cry3Bb to a Leaf Beetle, Plagiodera versicolora. Microbiol Spectr 2023; 11:e0504922. [PMID: 36976001 PMCID: PMC10101071 DOI: 10.1128/spectrum.05049-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 02/27/2023] [Indexed: 03/29/2023] Open
Abstract
Bacillus thuringiensis is widely used as a biopesticide, and its crystal protein expressed in transgenic crops has been successfully used for the management of insect pests. However, whether the midgut microbiota contribute to the Bt insecticidal mechanism remains controversial. We previously demonstrated that transplastomic poplar plants expressing Bt Cry3Bb are highly lethal to willow leaf beetle (Plagiodera versicolora), one of the major pests causing severe damage to Salicaceae plants such as willows and poplars. Here, we demonstrate that feeding poplar leaves expressing Cry3Bb to nonaxenic P. versicolora larvae leads to significantly accelerated mortality, and overgrowth and dysbiosis of the gut microbiota, compared with axenic larvae. Corroborating work done with Lepidopteran insects, plastid-expressed Cry3Bb can cause the lysis of the beetle's intestinal cells, lead to the entry of intestinal bacteria into the body cavity, and thus cause the dynamic changes in the flora of the midgut and blood cavity in P. versicolora. Reintroduction of Pseudomonas putida, a gut bacterium of P. versicolora, into axenic P. versicolora larvae further enhances mortality upon feeding on Cry3Bb-expressing poplar. Our results indicate the important contribution of host gut microbiota in promoting the B. thuringiensis crystal protein insecticidal activity and provide new insights into the mechanism of pest control by Bt-transplastomic approaches. IMPORTANCE The contribution of gut microbiota to Bacillus thuringiensis Cry3Bb insecticidal activity in a leaf beetle was demonstrated using transplastomic poplar plants, providing a potential new approach to improve the efficiency of plastid transformation technology for pest control by expression of Bt toxins.
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Affiliation(s)
- Xiaoyu Lei
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, School of Life Sciences, Hubei University, Wuhan, China
| | - Fengjuan Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, School of Life Sciences, Hubei University, Wuhan, China
| | - Jiang Zhang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, Hubei Hongshan Laboratory, School of Life Sciences, Hubei University, Wuhan, China
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
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Impact of Caterpillar Increased Feeding Rates on Reduction of Bt Susceptibility. Int J Mol Sci 2022; 23:ijms232314856. [PMID: 36499184 PMCID: PMC9735560 DOI: 10.3390/ijms232314856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/22/2022] [Accepted: 11/24/2022] [Indexed: 12/05/2022] Open
Abstract
The use of insect-resistant transgenic crops producing Bacillus thuringiensis protein Cry toxins (Bt) to control caterpillars is wide-spread. Development of a mechanism to prevent Bt from reaching its target site in the digestive system could result in Bt resistance and resistance to other insecticides active per os. Increased feeding rates by increasing temperature in tobacco budworms, Chloridea virescens, and bollworms, Helicoverpa zea, decreased Bt Cry1Ac susceptibility and mortality. The same was found in C. virescens for Bollgard II plant extract containing Bt Cry1Ac and Cry2Ab2 toxins. Furthermore, H. zea from the same inbred laboratory colony that fed faster independent of temperature manipulation were less susceptible to Bt intoxication. A laboratory derived C. virescens Bt resistant strain demonstrated a higher feeding rate on non-Bt artificial diet than the parental, Bt susceptible strain. A laboratory-reared Bt resistant fall armyworm, Spodoptera frugiperda, strain also fed faster on non-Bt diet compared to Bt susceptible caterpillars of the same species, both originally collected from corn. The studies in toto and the literature reviewed support the hypothesis that increased feeding rate is a behavioral mechanism for reducing caterpillar susceptibility to Bt. Its possible role in resistance needs further study.
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Gu X, Liu M, Wang B, Jiang K, Wang L. Identification and Expression Analysis of an Interacting Protein (LvFABP) that Mediates Vibrio parahaemolyticus AHPND Toxin Action. Front Immunol 2022; 13:940405. [PMID: 35860240 PMCID: PMC9289683 DOI: 10.3389/fimmu.2022.940405] [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: 05/10/2022] [Accepted: 06/09/2022] [Indexed: 11/13/2022] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND) caused by Vibrio parahaemolyticus causing AHPND (VPAHPND) is the most serious disease affecting shrimp farming. The PirAvp and PirBvp toxins of VPAHPND are known virulence factors. However, the corresponding target protein in shrimp that mediates their action has not been identified. By screening yeast two-hybrid cDNA libraries from intestine, stomach, and hepatopancreas of Litopenaeus vannamei, the protein with the largest increase in gene expression in shrimp hepatopancreas in response to VPAHPND challenge was identified and designated LvFABP. Analysis revealed high sequence homology of the LvFABP gene and a lipocalin/cytosolic fatty acid binding gene. Yeast two-hybrid pairwise analysis, GST-pull down assay, and far-western blot assay were performed to determine the interaction between LvFABP and PirBvp. LvFABP was able to directly bind to PirBvp. The expression of LvFABP in the hepatopancreas was significantly higher at P23 and P27 developmental stages of L. vannamei. RNA interference (RNAi) of LvFABP reduced the mortality, histopathological signs of AHPND in the hepatopancreas, and the number of virulent VPAHPND bacteria in the intestine, stomach, and hepatopancreas after VPAHPND challenge. We concluded that the LvFABP was involved in AHPND pathogenesis and acted as a VPAHPND toxin interacting protein. This is the first identification of VPAHPND toxin interacting protein from the shrimp digestive system by yeast two-hybrid library screening and were confirmed by in vitro protein interaction verification and in vivo challenge experiments. This study provides novel insight into the contributions of LvFABP towards AHPND pathogenesis in shrimp. The findings could inform AHPND preventative measures in shrimp farming.
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Affiliation(s)
- Xiaoqian Gu
- Chinese Academy Sciences (CAS) and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Mei Liu
- Shandong Key Laboratory of Disease Control in Mariculture, Marine Science Research Institute of Shandong Province, Qingdao, China
| | - Baojie Wang
- Chinese Academy Sciences (CAS) and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Keyong Jiang
- Chinese Academy Sciences (CAS) and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Lei Wang
- Chinese Academy Sciences (CAS) and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Lei Wang,
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Hernández-Martínez P, Bretsnyder EC, Baum JA, Haas JA, Head GP, Jerga A, Ferré J. Comparison of in vitro and in vivo binding site competition of Bacillus thuringiensis Cry1 proteins in two important maize pests. PEST MANAGEMENT SCIENCE 2022; 78:1457-1466. [PMID: 34951106 DOI: 10.1002/ps.6763] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 12/17/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Binding site models, derived from in vitro competition binding studies, have been widely used for predicting potential cross-resistance among insecticidal proteins from Bacillus thuringiensis. However, because discrepancies have been found between binding data and observed cross-resistance patterns in some insect species, new tools are required to study the functional relevance of the shared binding sites. RESULTS Here, an in vivo approach has been applied to the competition studies to establish the functional relevance of shared binding sites as determined by in vitro competition assays. Using Cry disabled proteins as competitors in mixed protein overlay assays, we assessed the preference of Cry1Ab, Cry1Fa, and Cry1A.105 proteins for shared binding sites in vivo in two important corn pests, Ostrinia nubilalis and Spodoptera frugiperda. CONCLUSION This study shows that in vivo and in vitro binding site competition assays can provide useful information to better ascertain whether different Cry proteins share binding sites and, consequently, whether cross-resistance due to binding site alteration can occur. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Patricia Hernández-Martínez
- Department of Genetics, University Institute of Biotechnology and Biomedicine, University of Valencia, Burjassot, Spain
| | - Eric C Bretsnyder
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - James A Baum
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Jeff A Haas
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Graham P Head
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Agoston Jerga
- Plant Biotechnology Program, Bayer Crop Science, Chesterfield, MO, USA
| | - Juan Ferré
- Department of Genetics, University Institute of Biotechnology and Biomedicine, University of Valencia, Burjassot, Spain
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Soto-Rodriguez SA, Lozano-Olvera R, Ramos-Clamont Montfort G, Zenteno E, Sánchez-Salgado JL, Vibanco-Pérez N, Aguilar Rendón KG. New Insights into the Mechanism of Action of PirAB from Vibrio Parahaemolyticus. Toxins (Basel) 2022; 14:toxins14040243. [PMID: 35448852 PMCID: PMC9030326 DOI: 10.3390/toxins14040243] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 02/06/2023] Open
Abstract
PirAB toxins secreted by Vibrio parahaemolyticus (Vp) harbor the pVA1 virulence plasmid, which causes acute hepatopancreatic necrosis disease (AHPND), an emerging disease in Penaeid shrimp that can cause 70–100% mortality and that has resulted in great economic losses since its first appearance. The cytotoxic effect of PirABVp on the epithelial cells of the shrimp hepatopancreas (Hp) has been extensively documented. New insights into the biological role of the PirBVp subunit show that it has lectin-like activity and recognizes mucin-like O-glycosidic structures in the shrimp Hp. The search for toxin receptors can lead to a better understanding of the infection mechanisms of the pathogen and the prevention of the host disease by blocking toxin–receptor interactions using a mimetic antagonist. There is also evidence that Vp AHPND changes the community structure of the microbiota in the surrounding water, resulting in a significant reduction of several bacterial taxa, especially Neptuniibacter spp. Considering these findings, the PirABvp toxin could exhibit a dual role of damaging the shrimp Hp while killing the surrounding bacteria.
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Affiliation(s)
- Sonia A. Soto-Rodriguez
- Laboratorio de Bacteriología, Centro de Investigación en Alimentación y Desarrollo, A.C. Unidad de Acuacultura y Manejo Ambiental, Av. Sábalo-Cerritos S/N A.P. 711, Mazatlán 82112, Sinaloa, Mexico; (R.L.-O.); (K.G.A.R.)
- Correspondence:
| | - Rodolfo Lozano-Olvera
- Laboratorio de Bacteriología, Centro de Investigación en Alimentación y Desarrollo, A.C. Unidad de Acuacultura y Manejo Ambiental, Av. Sábalo-Cerritos S/N A.P. 711, Mazatlán 82112, Sinaloa, Mexico; (R.L.-O.); (K.G.A.R.)
| | - Gabriela Ramos-Clamont Montfort
- Centro de Investigación en Alimentación y Desarrollo A.C., Carretera Gustavo Enrique Astiazarán Rosas, No. 46, Col. La Victoria, Hermosillo 83304, Sonora, Mexico;
| | - Edgar Zenteno
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City 04510, Mexico, Mexico; (E.Z.); (J.L.S.-S.)
| | - José Luis Sánchez-Salgado
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacan, Mexico City 04510, Mexico, Mexico; (E.Z.); (J.L.S.-S.)
| | - Norberto Vibanco-Pérez
- Laboratorio de Investigación en Biología Molecular e Inmunología, Unidad Académica de Ciencias Químico Biológicas y Farmacéuticas, Universidad Autónoma de Nayarit, Ciudad de la Cultura, Tepic 63190, Nayarit, Mexico;
| | - Karla G. Aguilar Rendón
- Laboratorio de Bacteriología, Centro de Investigación en Alimentación y Desarrollo, A.C. Unidad de Acuacultura y Manejo Ambiental, Av. Sábalo-Cerritos S/N A.P. 711, Mazatlán 82112, Sinaloa, Mexico; (R.L.-O.); (K.G.A.R.)
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Bao S, Gao S, Zhang M, Wang Y. Characterization of toxicity and structure of PirAB vc -like proteins that are structurally almost identical to shrimp AHPND-causing PirAB toxin. JOURNAL OF FISH DISEASES 2022; 45:315-326. [PMID: 34802159 DOI: 10.1111/jfd.13557] [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: 06/30/2021] [Revised: 10/31/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
PirAB is a binary toxic protein that causes acute hepatopancreatic necrosis disease (AHPND) in shrimp. Their closest homologs, PirAvc -like and PirBvc -like proteins, are encoded by two adjacent genes on a non-pVH plasmid from a Vibrio campbellii strain. Herein, PirABvc -like protein caused neither abnormalities nor death in shrimp postlarvae (Litopenaeus vannamei); furthermore, typical AHPND clinical signs were not observed. PirAvc -like protein corresponds to Cry toxin domain III (ligand-binding domain) and likely binds to N-acetylgalactosamine. The C-terminal and N-terminal of PirBvc -like resemble Cry toxin domain II (receptor-binding domain) and domain I (pore-forming domain), respectively. PirAvc -like and PirBvc -like proteins are structurally similar to PirA and PirB, respectively. Subtle structural differences between PirAvc -like protein and PirA appear to be involved in ligand-binding and binary protein complex formation. The difference in virulence of PirABvc -like and PirAB may result from the specific binding of the protein complex to distinct host receptors. These results shed light on the potential functions and host receptors of PirABvc -like proteins and their relationship with PirAB.
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Affiliation(s)
- Shuaiming Bao
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China
| | - Shuangshuang Gao
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China
| | - Mengmeng Zhang
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China
| | - Yongjie Wang
- College of Food Science and Technology, Shanghai Ocean University, Shanghai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Laboratory of Quality and Safety Risk Assessment for Aquatic Products on Storage and Preservation (Shanghai), Ministry of Agriculture, Shanghai, China
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Bacterial Toxins Active against Mosquitoes: Mode of Action and Resistance. Toxins (Basel) 2021; 13:toxins13080523. [PMID: 34437394 PMCID: PMC8402332 DOI: 10.3390/toxins13080523] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 06/18/2021] [Accepted: 06/19/2021] [Indexed: 12/25/2022] Open
Abstract
Larvicides based on the bacteria Bacillus thuringiensis svar. israelensis (Bti) and Lysinibacillus sphaericus are effective and environmentally safe compounds for the control of dipteran insects of medical importance. They produce crystals that display specific and potent insecticidal activity against larvae. Bti crystals are composed of multiple protoxins: three from the three-domain Cry type family, which bind to different cell receptors in the midgut, and one cytolytic (Cyt1Aa) protoxin that can insert itself into the cell membrane and act as surrogate receptor of the Cry toxins. Together, those toxins display a complex mode of action that shows a low risk of resistance selection. L. sphaericus crystals contain one major binary toxin that display an outstanding persistence in field conditions, which is superior to Bti. However, the action of the Bin toxin based on its interaction with a single receptor is vulnerable for resistance selection in insects. In this review we present the most recent data on the mode of action and synergism of these toxins, resistance issues, and examples of their use worldwide. Data reported in recent years improved our understanding of the mechanism of action of these toxins, showed that their combined use can enhance their activity and counteract resistance, and reinforced their relevance for mosquito control programs in the future years.
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Byrne MJ, Iadanza MG, Perez MA, Maskell DP, George RM, Hesketh EL, Beales PA, Zack MD, Berry C, Thompson RF. Cryo-EM structures of an insecticidal Bt toxin reveal its mechanism of action on the membrane. Nat Commun 2021; 12:2791. [PMID: 33990582 PMCID: PMC8121907 DOI: 10.1038/s41467-021-23146-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 03/25/2021] [Indexed: 12/11/2022] Open
Abstract
Insect pests are a major cause of crop losses worldwide, with an estimated economic cost of $470 billion annually. Biotechnological tools have been introduced to control such insects without the need for chemical pesticides; for instance, the development of transgenic plants harbouring genes encoding insecticidal proteins. The Vip3 (vegetative insecticidal protein 3) family proteins from Bacillus thuringiensis convey toxicity to species within the Lepidoptera, and have wide potential applications in commercial agriculture. Vip3 proteins are proposed to exert their insecticidal activity through pore formation, though to date there is no mechanistic description of how this occurs on the membrane. Here we present cryo-EM structures of a Vip3 family toxin in both inactive and activated forms in conjunction with structural and functional data on toxin-membrane interactions. Together these data demonstrate that activated Vip3Bc1 complex is able to insert into membranes in a highly efficient manner, indicating that receptor binding is the likely driver of Vip3 specificity.
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Affiliation(s)
- Matthew J Byrne
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Matthew G Iadanza
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, UK
| | - Marcos Arribas Perez
- Astbury Centre for Structural and Molecular Biology, School of Chemistry, Faculty of Engineering and Physical Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Daniel P Maskell
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Rachel M George
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Emma L Hesketh
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Paul A Beales
- Astbury Centre for Structural and Molecular Biology, School of Chemistry, Faculty of Engineering and Physical Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | | | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Cardiff, UK.
| | - Rebecca F Thompson
- Astbury Centre for Structural and Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
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Luangtrakul W, Boonchuen P, Jaree P, Kumar R, Wang HC, Somboonwiwat K. Cytotoxicity of Vibrio parahaemolyticus AHPND toxin on shrimp hemocytes, a newly identified target tissue, involves binding of toxin to aminopeptidase N1 receptor. PLoS Pathog 2021; 17:e1009463. [PMID: 33770150 PMCID: PMC8041169 DOI: 10.1371/journal.ppat.1009463] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 04/12/2021] [Accepted: 03/09/2021] [Indexed: 01/07/2023] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND) caused by PirABVP-producing strain of Vibrio parahaemolyticus, VPAHPND, has seriously impacted the shrimp production. Although the VPAHPND toxin is known as the VPAHPND virulence factor, a receptor that mediates its action has not been identified. An in-house transcriptome of Litopenaeus vannamei hemocytes allows us to identify two proteins from the aminopeptidase N family, LvAPN1 and LvAPN2, the proteins of which in insect are known to be receptors for Cry toxin. The membrane-bound APN, LvAPN1, was characterized to determine if it was a VPAHPND toxin receptor. The increased expression of LvAPN1 was found in hemocytes, stomach, and hepatopancreas after the shrimp were challenged with either VPAHPND or the partially purified VPAHPND toxin. LvAPN1 knockdown reduced the mortality, histopathological signs of AHPND in the hepatopancreas, and the number of virulent VPAHPND bacteria in the stomach after VPAHPND toxin challenge. In addition, LvAPN1 silencing prevented the toxin from causing severe damage to the hemocytes and sustained both the total hemocyte count (THC) and the percentage of living hemocytes. We found that the rLvAPN1 directly bound to both rPirAVP and rPirBVP toxins, supporting the notion that silencing of LvAPN1 prevented the VPAHPND toxin from passing through the cell membrane of hemocytes. We concluded that the LvAPN1 was involved in AHPND pathogenesis and acted as a VPAHPND toxin receptor mediating the toxin penetration into hemocytes. Besides, this was the first report on the toxic effect of VPAHPND toxin on hemocytes other than the known target tissues, hepatopancreas and stomach. A specific strain of Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (AHPND) in shrimp or VPAHPND produces a binary toxin (PirABvp toxin) that is previously known to induce cell death of stomach and hepatopancreas but the molecular mechanism has not been defined. Similar to Cry toxin receptor in insects, a novel aminopeptidase N1 protein from L. vannamei (LvAPN1) was identified as a putative receptor of VPAHPND toxin. Suppression of LvAPN1 reduced the number of AHPND virulence plasmids in stomach and occurrence of AHPND clinical sign, sustained the number of total hemocyte count, and elevated the number of viable hemocyte. We demonstrated that VPAHPND toxin challenge induces hemocyte cell damage and it interacts with LvAPN1 in vitro. Collectively, our finding suggested that not only stomach and hepatopancreas but also hemocyte are the VPAHPND target tissues where LvAPN1 serves as a VPAHPND toxin receptor. This study provides novel insight into the contributions of LvAPN1 receptor towards the AHPND pathogenesis in shrimp and may extend to the development of AHPND preventive measure in shrimp.
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Affiliation(s)
- Waruntorn Luangtrakul
- Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Pakpoom Boonchuen
- Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Phattarunda Jaree
- Center of Applied Shrimp Research and Innovation, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Ramya Kumar
- Department of Biotechnology and Bioindustry Sciences, College of Biosciences and Biotechnology, National Cheng Kung University, Tainan, Taiwan
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan
| | - Han-Ching Wang
- Department of Biotechnology and Bioindustry Sciences, College of Biosciences and Biotechnology, National Cheng Kung University, Tainan, Taiwan
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan
- * E-mail: (HC); (KS)
| | - Kunlaya Somboonwiwat
- Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- * E-mail: (HC); (KS)
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A novel anti-dipteran Bacillus thuringiensis strain: Unusual Cry toxin genes in a highly dynamic plasmid environment. Appl Environ Microbiol 2021; 87:AEM.02294-20. [PMID: 33310715 PMCID: PMC8090892 DOI: 10.1128/aem.02294-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacillus thuringiensis emerged as a major bioinsecticide on the global market. It offers a valuable alternative to chemical products classically utilized to control pest insects. Despite the efficiency of several strains and products available on the market, the scientific community is always on the lookout for novel toxins that can replace or supplement the existing products. In this study, H3, a novel B. thuringiensis strain showing mosquitocidal activity, was isolated from Lebanese soil and characterized at an in vivo, genomic and proteomic levels. H3 parasporal crystal is toxic on its own but displays an unusual killing profile with a higher LC50 than the reference B. thuringiensis serovar israelensis crystal proteins. In addition, H3 has a different toxicity order: it is more toxic to Aedes albopictus and Anopheles gambiae than to Culex pipiens Whole genome sequencing and crystal analysis revealed that H3 can produce eleven novel Cry proteins, eight of which are assembled in genes with an orf1-gap-orf2 organization, where orf2 is a potential Cry4-type crystallization domain. Moreover, pH3-180, the toxin-carrying plasmid, holds a wide repertoire of mobile genetic elements that amount to ca 22% of its size., including novel insertion sequences and class II transposable elements Two other large plasmids present in H3 carry genetic determinants for the production of many interesting molecules - such as chitinase, cellulase and bacitracin - that may add up to H3 bioactive properties. This study therefore reports a novel mosquitocidal Bacillus thuringiensis strain with unusual Cry toxin genes in a rich mobile DNA environment.IMPORTANCE Bacillus thuringiensis, a soil entomopathogenic bacteria, is at the base of many sustainable eco-friendly bio-insecticides. Hence stems the need to continually characterize insecticidal toxins. H3 is an anti-dipteran B. thuringiensis strain, isolated from Lebanese soil, whose parasporal crystal contains eleven novel Cry toxins and no Cyt toxins. In addition to its individual activity, H3 showed potential as a co-formulant with classic commercialized B. thuringiensis products, to delay the emergence of resistance and to shorten the time required for killing. On a genomic level, H3 holds three large plasmids, one of which carries the toxin-coding genes, with four occurrences of the distinct orf1-gap-orf2 organization. Moreover, this plasmid is extremely rich in mobile genetic elements, unlike its two co-residents. This highlights the important underlying evolutionary traits between toxin-carrying plasmids and the adaptation of a B. thuringiensis strain to its environment and insect host spectrum.
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Passive Immunization with Recombinant Antibody VLRB-PirA vp/PirB vp-Enriched Feeds against Vibrio parahaemolyticus Infection in Litopenaeus vannamei Shrimp. Vaccines (Basel) 2021; 9:vaccines9010055. [PMID: 33467013 PMCID: PMC7829966 DOI: 10.3390/vaccines9010055] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/11/2021] [Accepted: 01/12/2021] [Indexed: 11/17/2022] Open
Abstract
The causative agent of acute hepatopancreatic necrosis disease (AHPND) is the bacterium, Vibrio parahaemolyticus, which secretes toxins into the gastrointestinal tract of its host. Vibrio parahaemolyticus toxins A and B (PirAvp/PirBvp) have been implicated in the pathogenesis of this disease, and are, therefore, the focus of studies developing treatments for AHPND. We previously produced recombinant antibodies based on the hagfish variable lymphocyte receptor B (VLRB) capable of neutralizing some viruses, suggesting that this type of antibody may have a potential application for treatment of AHPND. Here, recombinant PirAvp/PirBvp, produced using a bacterial expression system, were used as antigens to screen a hagfish VLRB cDNA library to obtain PirAvp/PirBvp-specific antibodies. A cell line secreting these antibodies was established by screening and cloning the DNA extracted from hagfish B cells. Supernatants collected from cells secreting the PirAvp/PirBvp antibodies were collected and concentrated, and used to passively immunize shrimp to neutralize the toxins PirAvp or PirBvp associated with AHPND. Briefly, 10 μg of PirAvp and PirBvp antibodies, 7C12 and 9G10, respectively, were mixed with the shrimp feed, and fed to shrimp for three days consecutive days prior to experimentally infecting the shrimp with V. parahaemolyticus (containing toxins A and B), and resulting mortalities recorded for six days. Results showed significantly higher level of survival in shrimp fed with the PirBvp-9G10 antibody (60%) compared to the group fed the PirAvp-7C12 antibody (3%) and the control group (0%). This suggests that VLRB antibodies may be a suitable alternative to immunoglobulin-based antibodies, as passive immunization treatments for effective management of AHPND outbreaks within shrimp farms.
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Wang HC, Lin SJ, Mohapatra A, Kumar R, Wang HC. A Review of the Functional Annotations of Important Genes in the AHPND-Causing pVA1 Plasmid. Microorganisms 2020; 8:E996. [PMID: 32635298 PMCID: PMC7409025 DOI: 10.3390/microorganisms8070996] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 01/20/2023] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND) is a lethal shrimp disease. The pathogenic agent of this disease is a special Vibrio parahaemolyticus strain that contains a pVA1 plasmid. The protein products of two toxin genes in pVA1, pirAvp and pirBvp, targeted the shrimp's hepatopancreatic cells and were identified as the major virulence factors. However, in addition to pirAvp and pirBvp, pVA1 also contains about ~90 other open-reading frames (ORFs), which may encode functional proteins. NCBI BLASTp annotations of the functional roles of 40 pVA1 genes reveal transposases, conjugation factors, and antirestriction proteins that are involved in horizontal gene transfer, plasmid transmission, and maintenance, as well as components of type II and III secretion systems that may facilitate the toxic effects of pVA1-containing Vibrio spp. There is also evidence of a post-segregational killing (PSK) system that would ensure that only pVA1 plasmid-containing bacteria could survive after segregation. Here, in this review, we assess the functional importance of these pVA1 genes and consider those which might be worthy of further study.
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Affiliation(s)
- Hao-Ching Wang
- The Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei 110, Taiwan
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan;
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan; (S.-J.L.); (R.K.)
| | - Shin-Jen Lin
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan; (S.-J.L.); (R.K.)
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
| | - Arpita Mohapatra
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan;
- Mits School of Biotechnology, Utkal University, Bhubaneswar, Odisha 751004, India
| | - Ramya Kumar
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan; (S.-J.L.); (R.K.)
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
| | - Han-Ching Wang
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan; (S.-J.L.); (R.K.)
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
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14
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Al-Harbi A, Lary S, Edwards MG, Qusti S, Cockburn A, Poulsen M, Gatehouse AMR. A proteomic-based approach to study underlying molecular responses of the small intestine of Wistar rats to genetically modified corn (MON810). Transgenic Res 2019; 28:479-498. [PMID: 31172414 PMCID: PMC6848250 DOI: 10.1007/s11248-019-00157-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 05/27/2019] [Indexed: 12/13/2022]
Abstract
A genetically modified (GM) commercial corn variety, MON810, resistant to European corn borer, has been shown to be non-toxic to mammals in a number of rodent feeding studies carried out in accordance with OECD Guidelines. Insect resistance results from expression of the Cry1Ab gene encoding an insecticidal Bt protein that causes lysis and cell death in susceptible insect larvae by binding to midgut epithelial cells, which is a key determinant of Cry toxin species specificity. Whilst whole animal studies are still recognised as the 'gold standard' for safety assessment, they only provide indirect evidence for changes at the cellular/organ/tissue level. In contrast, omics-based technologies enable mechanistic understanding of toxicological or nutritional events at the cellular/receptor level. To address this important knowledge-gap and to gain insights into the underlying molecular responses in rat to MON810, differential gene expression in the epithelial cells of the small intestine of rats fed formulated diets containing MON810, its near isogenic line, two conventional corn varieties, and a commercial (Purina™) corn-based control diet were investigated using comparative proteomic profiling. Pairwise and five-way comparisons showed that the majority of proteins that were differentially expressed in the small intestine epithelial cells in response to consumption of the different diets in both 7-day and 28-day studies were related to lipid and carbohydrate metabolism and protein biosynthesis. Irrespective of the diet, a limited number of stress-related proteins were shown to be differentially expressed. However these stress-related proteins differed between diets. No adverse clinical or behavioural effects, or biomarkers of adverse health, were observed in rats fed GM corn compared to the other corn diets. These findings suggest that MON810 has negligible effects on the small intestine of rats at the cellular level compared with the well-documented toxicity observed in susceptible insects.
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Affiliation(s)
- Asmaa Al-Harbi
- Biochemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box: 42805, Jeddah, 21551, Kingdom of Saudi Arabia
| | - Sahira Lary
- Biochemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box: 42805, Jeddah, 21551, Kingdom of Saudi Arabia
| | - Martin G Edwards
- School of Natural and Environmental Sciences, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK
| | - Safaa Qusti
- Biochemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box: 42805, Jeddah, 21551, Kingdom of Saudi Arabia
| | - Andrew Cockburn
- School of Natural and Environmental Sciences, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK
| | - Morten Poulsen
- The National Food Institute, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Angharad M R Gatehouse
- School of Natural and Environmental Sciences, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK.
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Pore-Forming Proteins from Cnidarians and Arachnids as Potential Biotechnological Tools. Toxins (Basel) 2019; 11:toxins11060370. [PMID: 31242582 PMCID: PMC6628452 DOI: 10.3390/toxins11060370] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 06/18/2019] [Accepted: 06/21/2019] [Indexed: 12/31/2022] Open
Abstract
Animal venoms are complex mixtures of highly specialized toxic molecules. Cnidarians and arachnids produce pore-forming proteins (PFPs) directed against the plasma membrane of their target cells. Among PFPs from cnidarians, actinoporins stand out for their small size and molecular simplicity. While native actinoporins require only sphingomyelin for membrane binding, engineered chimeras containing a recognition antibody-derived domain fused to an actinoporin isoform can nonetheless serve as highly specific immunotoxins. Examples of such constructs targeted against malignant cells have been already reported. However, PFPs from arachnid venoms are less well-studied from a structural and functional point of view. Spiders from the Latrodectus genus are professional insect hunters that, as part of their toxic arsenal, produce large PFPs known as latrotoxins. Interestingly, some latrotoxins have been identified as potent and highly-specific insecticides. Given the proteinaceous nature of these toxins, their promising future use as efficient bioinsecticides is discussed throughout this Perspective. Protein engineering and large-scale recombinant production are critical steps for the use of these PFPs as tools to control agriculturally important insect pests. In summary, both families of PFPs, from Cnidaria and Arachnida, appear to be molecules with promising biotechnological applications.
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Lin SJ, Chen YF, Hsu KC, Chen YL, Ko TP, Lo CF, Wang HC, Wang HC. Structural Insights to the Heterotetrameric Interaction between the Vibrio parahaemolyticus PirA vp and PirB vp Toxins and Activation of the Cry-Like Pore-Forming Domain. Toxins (Basel) 2019; 11:toxins11040233. [PMID: 31013623 PMCID: PMC6520838 DOI: 10.3390/toxins11040233] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/16/2019] [Accepted: 04/19/2019] [Indexed: 02/06/2023] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND) is a newly emergent penaeid shrimp disease which can cause 70-100% mortality in Penaeus vannamei and Penaeus monodon, and has resulted in enormous economic losses since its appearance. AHPND is caused by the specific strains of Vibrio parahaemolyticus that harbor the pVA1 plasmid and express PirAvp and PirBvp toxins. These two toxins have been reported to form a binary complex. When both are present, they lead to the death of shrimp epithelial cells in the hepatopancreas and cause the typical histological symptoms of AHPND. However, the binding mode of PirAvp and PirBvp has not yet been determined. Here, we used isothermal titration calorimetry (ITC) to measure the binding affinity of PirAvp and PirBvp. Since the dissociation constant (Kd = 7.33 ± 1.20 μM) was considered too low to form a sufficiently stable complex for X-ray crystallographic analysis, we used alternative methods to investigate PirAvp-PirBvp interaction, first by using gel filtration to evaluate the molecular weight of the PirAvp/PirBvp complex, and then by using cross-linking and hydrogen-deuterium exchange (HDX) mass spectrometry to further understand the interaction interface between PirAvp and PirBvp. Based on these results, we propose a heterotetrameric interaction model of this binary toxin complex. This model provides insight of how conformational changes might activate the PirBvp N-terminal pore-forming domain and should be helpful for devising effective anti-AHPND strategies in the future.
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Affiliation(s)
- Shin-Jen Lin
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
| | - Yi-Fan Chen
- The Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei 110, Taiwan.
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
| | - Kai-Cheng Hsu
- Graduate Institute of Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
- Ph.D. Program for Cancer Molecular Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
- Biomedical Commercialization Center, Taipei Medical University, Taipei 110, Taiwan.
| | - Yun-Ling Chen
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan.
| | - Chu-Fang Lo
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan.
| | - Han-Ching Wang
- Department of Biotechnology and Bioindustry Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan.
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan.
| | - Hao-Ching Wang
- The Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University and Academia Sinica, Taipei 110, Taiwan.
- Graduate Institute of Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan.
- International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan 701, Taiwan.
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17
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Recent advancement on chemical arsenal of Bt toxin and its application in pest management system in agricultural field. 3 Biotech 2018; 8:201. [PMID: 29607282 DOI: 10.1007/s13205-018-1223-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2017] [Accepted: 03/22/2018] [Indexed: 10/17/2022] Open
Abstract
Bacillus thuringiensis (Bt) is a Gram-positive, spore-forming, soil bacterium, which is very popular bio-control agent in agricultural and forestry. In general, B. thuringiensis secretes an array of insecticidal proteins including toxins produced during vegetative growth phase (such as secreted insecticidal protein, Sip; vegetative insecticidal proteins, Vip), parasporal crystalline δ-endotoxins produced during vegetative stationary phase (such as cytolytic toxin, Cyt; and crystal toxin, Cry), and β-exotoxins. Till date, a wide spectrum of Cry proteins has been reported and most of them belong to three-domain-Cry toxins, Bin-like toxin, and Etx_Mtx2-like toxins. To the best of our knowledge, neither Bt insecticidal toxins are exclusive to Bt nor all the strains of Bt are capable of producing insecticidal Bt toxins. The lacuna in their latest classification has also been discussed. In this review, the updated information regarding the insecticidal Bt toxins and their different mode of actions were summarized. Before applying the Bt toxins on agricultural field, the non-specific effects of toxins should be investigated. We also have summarized the problem of insect resistance and the strategies to combat with this problem. We strongly believe that this information will help a lot to the budding researchers in the field of modern pest control biotechnology.
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Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirA vp and PirB vp Toxins. Mar Drugs 2017; 15:md15120373. [PMID: 29194352 PMCID: PMC5742833 DOI: 10.3390/md15120373] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 11/14/2017] [Accepted: 11/17/2017] [Indexed: 02/01/2023] Open
Abstract
In aquaculture, shrimp farming is a popular field. The benefits of shrimp farming include a relatively short grow-out time, high sale price, and good cost recovery. However, outbreaks of serious diseases inflict serious losses, and acute hepatopancreatic necrosis disease (AHPND) is an emerging challenge to this industry. In South American white shrimp (Penaeus vannamei) and grass shrimp (Penaeus monodon), this disease has a 70–100% mortality. The pathogenic agent of AHPND is a specific strain of Vibrio parahaemolyticus which contains PirAvp and PirBvp toxins encoded in the pVA1 plasmid. PirAvp and PirBvp have been shown to cause the typical histological symptoms of AHPND in infected shrimps, and in this review, we will focus on our structural understanding of these toxins. By analyzing their structures, a possible cytotoxic mechanism, as well as strategies for anti-AHPND drug design, is proposed.
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Yang Q, Zhang J, Li T, Liu S, Song P, Nangong Z, Wang Q. PirAB protein from Xenorhabdus nematophila HB310 exhibits a binary toxin with insecticidal activity and cytotoxicity in Galleria mellonella. J Invertebr Pathol 2017; 148:43-50. [PMID: 28438456 DOI: 10.1016/j.jip.2017.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/05/2017] [Accepted: 04/20/2017] [Indexed: 11/17/2022]
Abstract
PirAB (Photorhabdus insect-related proteins, PirAB) toxin was initially found in the Photorhabdus luminescens TT01 strain and has been shown to be a binary toxin with high insecticidal activity. Based on GenBank data, this gene was also found in the Xenorhabdus nematophila genome sequence. The predicted amino acid sequence of pirA and pirB in the genome of X. nematophila showed 51% and 50% identity with those gene sequences from P. luminescens. The purpose of this experiment is to identify the relevant information for this toxin gene in X. nematophila. The pirA, pirB and pirAB genes of X. nematophila HB310 were cloned and expressed in Escherichia coli BL21 (DE3) using the pET-28a vector. A PirAB-fusion protein (PirAB-F) was constructed by linking the pirA and pirB genes with the flexible linker (Gly)4 DNA encoding sequence and then efficiently expressed in E. coli. The hemocoel and oral insecticidal activities of the recombinant proteins were analyzed against the larvae of Galleria mellonella. The results show that PirA/B alone, PirA/B mixture, co-expressed PirAB protein, and PirAB-F all had no oral insecticidal activity against the second-instar larvae of G. mellonella. Only PirA/B mixture and co-expressed PirAB protein had hemocoel insecticidal activity against G. mellonella fifth-instar larvae, with an LD50 of 2.718μg/larva or 1.566μg/larva, respectively. Therefore, we confirmed that PirAB protein of X. nematophila HB310 is a binary insecticidal toxin. The successful expression and purification of PirAB laid a foundation for further studies on the function, insecticidal mechanism and expression regulation of the binary toxin.
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Affiliation(s)
- Qing Yang
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China
| | - Jie Zhang
- Luanping State-owned Forestry Farm Management of Chengde City, 068250 Chengde, China
| | - Tianhui Li
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China
| | - Shen Liu
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China
| | - Ping Song
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China
| | - Ziyan Nangong
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China.
| | - Qinying Wang
- College of Plant Protection, Hebei Agricultural University, 071001 Baoding, Hebei Province, China
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Midgut microbiota and host immunocompetence underlie Bacillus thuringiensis killing mechanism. Proc Natl Acad Sci U S A 2016; 113:9486-91. [PMID: 27506800 DOI: 10.1073/pnas.1521741113] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacillus thuringiensis is a widely used bacterial entomopathogen producing insecticidal toxins, some of which are expressed in insect-resistant transgenic crops. Surprisingly, the killing mechanism of B. thuringiensis remains controversial. In particular, the importance of the septicemia induced by the host midgut microbiota is still debated as a result of the lack of experimental evidence obtained without drastic manipulation of the midgut and its content. Here this key issue is addressed by RNAi-mediated silencing of an immune gene in a lepidopteran host Spodoptera littoralis, leaving the midgut microbiota unaltered. The resulting cellular immunosuppression was characterized by a reduced nodulation response, which was associated with a significant enhancement of host larvae mortality triggered by B. thuringiensis and a Cry toxin. This was determined by an uncontrolled proliferation of midgut bacteria, after entering the body cavity through toxin-induced epithelial lesions. Consequently, the hemolymphatic microbiota dramatically changed upon treatment with Cry1Ca toxin, showing a remarkable predominance of Serratia and Clostridium species, which switched from asymptomatic gut symbionts to hemocoelic pathogens. These experimental results demonstrate the important contribution of host enteric flora in B. thuringiensis-killing activity and provide a sound foundation for developing new insect control strategies aimed at enhancing the impact of biocontrol agents by reducing the immunocompetence of the host.
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Nair MS, Dean DH. Composition of the Putative Prepore Complex of Bacillus thuringiensis Cry1Ab Toxin. ACTA ACUST UNITED AC 2015; 5:179-188. [PMID: 26702367 PMCID: PMC4686277 DOI: 10.4236/abc.2015.54014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Prepore formation is hypothesized to be an obligate step in the insertion of Cry1Ab toxin into insect brush border membrane vesicles. We examined the architecture of the putative prepore when isolated using the published protocols [1] [2]. Our results demonstrate that the putative prepore form of Cry1Ab is a combination of receptor proteins attached to the toxin, when purified. The results also suggest that this prepore form as prepared by the methods published is different from other membrane-extracted oligomeric forms of Cry toxins and prepore of other toxins in general. While most other known prepores are composed of multimers of a single protein, the Cry1Ab prepore, as generated, is a protein-receptor complex oligomer and monomers of Cry toxins.
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Affiliation(s)
- Manoj S Nair
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA ; Aaron Diamond AIDS Research Center, Rockefeller University, New York, NY, USA
| | - Donald H Dean
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
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22
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Rojko N, Dalla Serra M, Maček P, Anderluh G. Pore formation by actinoporins, cytolysins from sea anemones. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:446-56. [PMID: 26351738 DOI: 10.1016/j.bbamem.2015.09.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/31/2015] [Accepted: 09/02/2015] [Indexed: 11/30/2022]
Abstract
Actinoporins (APs) from sea anemones are ~20 kDa pore forming toxins with a β-sandwich structure flanked by two α-helices. The molecular mechanism of APs pore formation is composed of several well-defined steps. APs bind to membrane by interfacial binding site composed of several aromatic amino acid residues that allow binding to phosphatidylcholine and specific recognition of sphingomyelin. Subsequently, the N-terminal α-helix from the β-sandwich has to be inserted into the lipid/water interphase in order to form a functional pore. Functional studies and single molecule imaging revealed that only several monomers, 3-4, oligomerise to form a functional pore. In this model the α-helices and surrounding lipid molecules build toroidal pore. In agreement, AP pores are transient and electrically heterogeneous. On the contrary, crystallized oligomers of actinoporin fragaceatoxin C were found to be composed of eight monomers with no lipids present between the adjacent α-helices. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Maur Dalla Serra and Franco Gambale.
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Affiliation(s)
- Nejc Rojko
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia
| | - Mauro Dalla Serra
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche & Fondazione Bruno Kessler, via alla Cascata 56/C, 38123 Trento, Italy
| | - Peter Maček
- Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia
| | - Gregor Anderluh
- Laboratory for Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Hajdrihova 19, 1000 Ljubljana, Slovenia; Department of Biology, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia.
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The opportunistic marine pathogen Vibrio parahaemolyticus becomes virulent by acquiring a plasmid that expresses a deadly toxin. Proc Natl Acad Sci U S A 2015; 112:10798-803. [PMID: 26261348 DOI: 10.1073/pnas.1503129112] [Citation(s) in RCA: 284] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acute hepatopancreatic necrosis disease (AHPND) is a severe, newly emergent penaeid shrimp disease caused by Vibrio parahaemolyticus that has already led to tremendous losses in the cultured shrimp industry. Until now, its disease-causing mechanism has remained unclear. Here we show that an AHPND-causing strain of V. parahaemolyticus contains a 70-kbp plasmid (pVA1) with a postsegregational killing system, and that the ability to cause disease is abolished by the natural absence or experimental deletion of the plasmid-encoded homologs of the Photorhabdus insect-related (Pir) toxins PirA and PirB. We determined the crystal structure of the V. parahaemolyticus PirA and PirB (PirA(vp) and PirB(vp)) proteins and found that the overall structural topology of PirA(vp)/PirB(vp) is very similar to that of the Bacillus Cry insecticidal toxin-like proteins, despite the low sequence identity (<10%). This structural similarity suggests that the putative PirAB(vp) heterodimer might emulate the functional domains of the Cry protein, and in particular its pore-forming activity. The gene organization of pVA1 further suggested that pirAB(vp) may be lost or acquired by horizontal gene transfer via transposition or homologous recombination.
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Zhao C, Jurat-Fuentes JL, Abdelgaffar HM, Pan H, Song F, Zhang J. Identification of a New cry1I-Type Gene as a Candidate for Gene Pyramiding in Corn To Control Ostrinia Species Larvae. Appl Environ Microbiol 2015; 81:3699-705. [PMID: 25795679 PMCID: PMC4421046 DOI: 10.1128/aem.00379-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/17/2015] [Indexed: 11/20/2022] Open
Abstract
Pyramiding of diverse cry toxin genes from Bacillus thuringiensis with different modes of action is a desirable strategy to delay the evolution of resistance in the European corn borer (Ostrinia nubilalis). Considering the dependency of susceptibility to Cry toxins on toxin binding to receptors in the midgut of target pests, a diverse mode of action is commonly defined as recognition of unique binding sites in the target insect. In this study, we present a novel cry1Ie toxin gene (cry1Ie2) as a candidate for pyramiding with Cry1Ab or Cry1Fa in corn to control Ostrinia species larvae. The new toxin gene encodes an 81-kDa protein that is processed to a protease-resistant core form of approximately 55 kDa by trypsin digestion. The purified protoxin displayed high toxicity to Ostrinia furnacalis and O. nubilalis larvae but low to no activity against Spodoptera or heliothine species or the coleopteran Tenebrio molitor. Results of binding assays with (125)I-labeled Cry1Ab toxin and brush border membrane vesicles from O. nubilalis larvae demonstrated that Cry1Ie2 does not recognize the Cry1Ab binding sites in that insect. Reciprocal competition binding assays with biotin-labeled Cry1Ie2 confirmed the lack of shared sites with Cry1Ab or Cry1Fa in O. nubilalis brush border membrane vesicles. These data support Cry1Ie2 as a good candidate for pyramiding with Cry1Ab or Cry1Fa in corn to increase the control of O. nubilalis and reduce the risk of resistance evolution.
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Affiliation(s)
- Can Zhao
- College of Plant Science, Jilin University, Changchun, Jilin, China State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Juan Luis Jurat-Fuentes
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Heba M Abdelgaffar
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Hongyu Pan
- College of Plant Science, Jilin University, Changchun, Jilin, China
| | - Fuping Song
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Jie Zhang
- 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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Park Y, Ahn SJ, Vogel H, Kim Y. Integrin β subunit and its RNA interference in immune and developmental processes of the Oriental tobacco budworm, Helicoverpa assulta. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 47:59-67. [PMID: 25008242 DOI: 10.1016/j.dci.2014.06.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 06/26/2014] [Accepted: 06/28/2014] [Indexed: 06/03/2023]
Abstract
Integrins are cell surface heterodimeric proteins interacting with the extracellular matrix and mediating environmental signals through cell membranes. A full-length cDNA sequence of the integrin β1 subunit gene (HaITGb1) was cloned from the Oriental tobacco budworm, Helicoverpa assulta, and analyzed for its physiological role in both immune response and development. HaITGb1 was expressed in all developmental stages from egg to adult and in all tested larval tissues of hemocytes, fat body, gut, and epidermis. Utilizing an RNA interference (RNAi) approach, injection of a specific double-stranded RNA (dsRNA) in larvae suppressed HaITGb1 transcript levels and significantly impaired hemocytes in their extracellular matrix adherence properties. Furthermore, the RNAi treatment significantly suppressed hemocyte nodule formation in response to bacterial challenge, which resulted in significantly enhanced susceptibility to both pathogenic and non-pathogenic bacteria. The RNAi treatment also interfered with H. assulta larval and pupal development. These results suggest that the extensive and constitutive expression of HaITGb1 is necessary for H. assulta to perform an efficient immune response against microbial pathogens and undergo normal immature development.
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Affiliation(s)
- Youngjin Park
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea
| | - Seung-Joon Ahn
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany
| | - Heiko Vogel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena 07745, Germany
| | - Yonggyun Kim
- Department of Bioresource Sciences, Andong National University, Andong 760-749, Republic of Korea.
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Melo ALDA, Soccol VT, Soccol CR. Bacillus thuringiensis: mechanism of action, resistance, and new applications: a review. Crit Rev Biotechnol 2014; 36:317-26. [DOI: 10.3109/07388551.2014.960793] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Lucena WA, Pelegrini PB, Martins-de-Sa D, Fonseca FCA, Gomes JE, de Macedo LLP, da Silva MCM, Oliveira RS, Grossi-de-Sa MF. Molecular approaches to improve the insecticidal activity of Bacillus thuringiensis Cry toxins. Toxins (Basel) 2014; 6:2393-423. [PMID: 25123558 PMCID: PMC4147589 DOI: 10.3390/toxins6082393] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 06/23/2014] [Accepted: 06/27/2014] [Indexed: 02/01/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity.
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Affiliation(s)
- Wagner A. Lucena
- Embrapa Cotton, Campina Grande, 58428-095, PB, Brazil; E-Mail:
- Graduate Program in Cellular and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, 91501-970, RS, Brazil
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Patrícia B. Pelegrini
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Diogo Martins-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Fernando C. A. Fonseca
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Jose E. Gomes
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Department of Molecular Biology, Federal University of Brasília, Brasília, 70910-900, DF, Brazil
| | - Leonardo L. P. de Macedo
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria Cristina M. da Silva
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
| | - Raquel S. Oliveira
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
| | - Maria F. Grossi-de-Sa
- Embrapa Genetic Resources and Biotechnology, Brasília, 70779-917, DF, Brazil; E-Mails: (P.B.P.); (D.M.-S.); (F.C.A.F.); (J.E.G.); (L.L.P.M.); (M.C.M.S.); (R.S.)
- Post-Graduation of Genomic Sciences and Biotechnology, Catholic University of Brasilia, Brasília, 70790-160, DF, Brazil
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Iatsenko I, Nikolov A, Sommer RJ. Identification of distinct Bacillus thuringiensis 4A4 nematicidal factors using the model nematodes Pristionchus pacificus and Caenorhabditis elegans. Toxins (Basel) 2014; 6:2050-63. [PMID: 25025708 PMCID: PMC4113741 DOI: 10.3390/toxins6072050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/02/2014] [Accepted: 06/27/2014] [Indexed: 01/10/2023] Open
Abstract
Bacillus thuringiensis has been extensively used for the biological control of insect pests. Nematicidal B. thuringiensis strains have also been identified; however, virulence factors of such strains are poorly investigated. Here, we describe virulence factors of the nematicidal B. thuringiensis 4A4 strain, using the model nematodes Pristionchus pacificus and Caenorhabditis elegans. We show that B. thuringiensis 4A4 kills both nematodes via intestinal damage. Whole genome sequencing of B. thuringiensis 4A4 identified Cry21Ha, Cry1Ba, Vip1/Vip2 and β-exotoxin as potential nematicidal factors. Only Cry21Ha showed toxicity to C. elegans, while neither Cry nor Vip toxins were active against P. pacificus, when expressed in E. coli. Purified crystals also failed to intoxicate P. pacificus, while autoclaved spore-crystal mixture of B. thuringiensis 4A4 retained toxicity, suggesting that primary β-exotoxin is responsible for P. pacificus killing. In support of this, we found that a β-exotoxin-deficient variant of B. thuringiensis 4A4, generated by plasmid curing lost virulence to the nematodes. Thus, using two model nematodes we revealed virulence factors of the nematicidal strain B. thuringiensis 4A4 and showed the multifactorial nature of its virulence.
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Affiliation(s)
- Igor Iatsenko
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstrasse 37, 72076 Tuebingen, Germany.
| | - Angel Nikolov
- Institute for Chemistry and Biochemistry, Free University of Berlin, Thielallee 63, 14195 Berlin, Germany.
| | - Ralf J Sommer
- Department for Evolutionary Biology, Max-Planck Institute for Developmental Biology, Spemannstrasse 37, 72076 Tuebingen, Germany.
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Yao J, Buschman LL, Lu N, Khajuria C, Zhu KY. Changes in gene expression in the larval gut of Ostrinia nubilalis in Response to Bacillus thuringiensis Cry1Ab protoxin ingestion. Toxins (Basel) 2014; 6:1274-94. [PMID: 24704690 PMCID: PMC4014733 DOI: 10.3390/toxins6041274] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 03/13/2014] [Accepted: 03/26/2014] [Indexed: 12/04/2022] Open
Abstract
We developed a microarray based on 2895 unique transcripts assembled from 15,000 cDNA sequences from the European corn borer (Ostrinia nubilalis) larval gut. This microarray was used to monitor gene expression in early third-instar larvae of Bacillus thuringiensis (Bt)-susceptible O. nubilalis after 6 h feeding on diet, with or without the Bt Cry1Ab protoxin. We identified 174 transcripts, for which the expression was changed more than two-fold in the gut of the larvae fed Cry1Ab protoxin (p < 0.05), representing 80 down-regulated and 94 up-regulated transcripts. Among 174 differentially expressed transcripts, 13 transcripts putatively encode proteins that are potentially involved in Bt toxicity, and these transcripts include eight serine proteases, three aminopeptidases, one alkaline phosphatase, and one cadherin. The expressions of trypsin-like protease and three aminopeptidase transcripts were variable, but two potential Bt-binding proteins, alkaline phosphatase and cadherin were consistently up-regulated in larvae fed Cry1Ab protoxin. The significantly up and down-regulated transcripts may be involved in Cry1Ab toxicity by activation, degradation, toxin binding, and other related cellular responses. This study is a preliminary survey of Cry1Ab protoxin-induced transcriptional responses in O. nubilalis gut and our results are expected to help with further studies on Bt toxin-insect interactions at the molecular level.
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Affiliation(s)
- Jianxiu Yao
- Department of Entomology, 123 Waters Hall, Kansas State University, Manhattan, KS 66506, USA.
| | - Lawrent L Buschman
- Department of Entomology, 123 Waters Hall, Kansas State University, Manhattan, KS 66506, USA.
| | - Nanyan Lu
- Bioinformatics Center, Kansas State University, Manhattan, KS 66506, USA.
| | - Chitvan Khajuria
- Department of Entomology, 123 Waters Hall, Kansas State University, Manhattan, KS 66506, USA.
| | - Kun Yan Zhu
- Department of Entomology, 123 Waters Hall, Kansas State University, Manhattan, KS 66506, USA.
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Li N, Wang J, Han H, Huang L, Shao F, Li X. Intravital imaging of Bacillus thuringiensis Cry1A toxin binding sites in the midgut of silkworm. Anal Biochem 2014; 447:90-7. [DOI: 10.1016/j.ab.2013.11.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/25/2013] [Accepted: 11/07/2013] [Indexed: 12/31/2022]
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Sengupta A, Sarkar A, Priya P, Ghosh Dastidar S, Das S. New insight to structure-function relationship of GalNAc mediated primary interaction between insecticidal Cry1Ac toxin and HaALP receptor of Helicoverpa armigera. PLoS One 2013; 8:e78249. [PMID: 24205171 PMCID: PMC3813429 DOI: 10.1371/journal.pone.0078249] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 09/11/2013] [Indexed: 11/30/2022] Open
Abstract
Over the last few decades Cry1Ac toxin has been widely used in controlling the insect attack due to its high specificity towards target insects. The pore-forming toxin undergoes a complex mechanism in the insect midgut involving sequential interaction with specific glycosylated receptors in which terminal GalNAc molecule plays a vital role. Recent studies on Cry toxins interactions with specific receptors revealed the importance of several amino acid residues in domain III of Cry1Ac, namely Q509, N510, R511, Y513 and W545, serve as potential binding sites that surround the putative GalNAc binding pocket and mediate the toxin-receptor interaction. In the present study, alanine substitution mutations were generated in the Cry1Ac domain III region and functional significance of those key residues was monitored by insect bioassay on Helicoverpa armigera larvae. In addition, ligand blot analysis and SPR binding assay was performed to monitor the binding characteristics of Cry1Ac wild type and mutant toxins towards HaALP receptor isolated from Helicoverpa armigera. Mutagenesis data revealed that, alanine substitutions in R511, Y513 and W545 substantially impacted the relative affinity towards HaALP receptor and toxicity toward target insect. Furthermore, in silico study of GalNAc-mediated interaction also confirmed the important roles of these residues. This structural analysis will provide a detail insight for evaluating and engineering new generation Cry toxins to address the problem of change in insect behavioral patterns.
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Affiliation(s)
- Anindita Sengupta
- Division of Plant Biology, Bose Institute, Kolkata, West Bengal, India
| | - Anindya Sarkar
- Division of Plant Biology, Bose Institute, Kolkata, West Bengal, India
| | - Prerna Priya
- Bioinformatics Centre, Bose Institute, Kolkata, West Bengal, India
| | | | - Sampa Das
- Division of Plant Biology, Bose Institute, Kolkata, West Bengal, India
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Zhang X, Kain W, Wang P. Sequence variation and differential splicing of the midgut cadherin gene in Trichoplusia ni. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:712-723. [PMID: 23743444 DOI: 10.1016/j.ibmb.2013.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 05/07/2013] [Accepted: 05/21/2013] [Indexed: 06/02/2023]
Abstract
The insect midgut cadherin serves as an important receptor for the Cry toxins from Bacillus thuringiensis (Bt). Variation of the cadherin in insect populations provides a genetic potential for development of cadherin-based Bt resistance in insect populations. Sequence analysis of the cadherin from the cabbage looper, Trichoplusia ni, together with cadherins from 18 other lepidopterans showed a similar phylogenetic relationship of the cadherins to the phylogeny of Lepidoptera. The midgut cadherin in three laboratory populations of T. ni exhibited high variability, although the resistance to Bt toxin Cry1Ac in the T. ni strain is not genetically associated with cadherin gene mutations. A total of 142 single nucleotide polymorphisms (SNPs) were identified in the cadherin cDNAs from the T. ni strains, including 20 missense mutations. In addition, insertion and deletion polymorphisms (indels) were also identified in the cadherin alleles in T. ni. More interestingly, the results from this study reveal that differential splicing of mRNA also occurs in the cadherin gene expression. Therefore, variation of the midgut cadherin in insects may not only be caused by cadherin gene mutations, but could also result from alternative splicing of its mRNA regulated by factors acting in trans. Analysis of cadherin gene alleles in F2, F3 and F4 progenies from the cross between the Cry1Ac resistant and the susceptible strain after consecutive selections with Cry1Ac for three generations showed that selection with Cry1Ac did not result in an increase of frequencies of the cadherin alleles originated from the resistant strain.
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Affiliation(s)
- Xin Zhang
- Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA
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A novel Bacillus thuringiensis Cry-like protein from a rare filamentous strain promotes crystal localization within the exosporium. Appl Environ Microbiol 2013; 79:5774-6. [PMID: 23851091 DOI: 10.1128/aem.01206-13] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutation of a novel cry-like gene (cry256) from Bacillus thuringiensis resulted in a protein crystal, normally located within the spore's exosporium, being found predominately outside the exosporium. The cry256 gene codes for a 3-domain Cry-like protein that does not correspond to any of the known Cry protein holotypes.
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Differential role of Manduca sexta aminopeptidase-N and alkaline phosphatase in the mode of action of Cry1Aa, Cry1Ab, and Cry1Ac toxins from Bacillus thuringiensis. Appl Environ Microbiol 2013; 79:4543-50. [PMID: 23686267 DOI: 10.1128/aem.01062-13] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Aminopeptidase-N (APN1) and alkaline phosphatase (ALP) proteins located in the midgut epithelium of Manduca sexta have been implicated as receptors for Cry1Aa, Cry1Ab, and Cry1Ac insecticidal proteins produced by Bacillus thuringiensis subsp. kurstaki. In this study, we analyzed the roles of ALP and APN1 in the toxicity of these three Cry1A proteins. Ligand blot analysis using brush border membrane vesicles of M. sexta showed that Cry1Aa and Cry1Ab bind preferentially to ALP during early instars while binding to APN was observed after the third instar of larval development. Cry1Ac binds to APN throughout all larval development, with no apparent binding to ALP. ALP was cloned from M. sexta midgut RNA and expressed in Escherichia coli. Surface plasmon resonance binding analysis showed that recombinant ALP binds to Cry1Ac with 16-fold lower affinity than to Cry1Aa or Cry1Ab. Downregulation of APN1 and ALP expression by RNA interference (RNAi) using specific double-stranded RNA correlated with a reduction of transcript and protein levels. Toxicity analysis of the three Cry1A proteins in ALP- or APN1-silenced larvae showed that Cry1Aa relies similarly on both receptor molecules for toxicity. In contrast, RNAi experiments showed that ALP is more important than APN for Cry1Ab toxicity, while Cry1Ac relied principally on APN1. These results indicated that ALP and APN1 have a differential role in the mode of action of Cry1A toxins, suggesting that B. thuringiensis subsp. kurstaki produces different Cry1A toxins that in conjunction target diverse midgut proteins to exert their insecticidal effect.
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Navarro-Cerrillo G, Hernández-Martínez P, Vogel H, Ferré J, Herrero S. A new gene superfamily of pathogen-response (repat) genes in Lepidoptera: Classification and expression analysis. Comp Biochem Physiol B Biochem Mol Biol 2013; 164:10-7. [DOI: 10.1016/j.cbpb.2012.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/21/2012] [Accepted: 09/25/2012] [Indexed: 01/17/2023]
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Chakrabarti S, Liehl P, Buchon N, Lemaitre B. Infection-Induced Host Translational Blockage Inhibits Immune Responses and Epithelial Renewal in the Drosophila Gut. Cell Host Microbe 2012; 12:60-70. [DOI: 10.1016/j.chom.2012.06.001] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 05/09/2012] [Accepted: 06/21/2012] [Indexed: 12/25/2022]
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Hu Y, Aroian RV. Bacterial pore-forming proteins as anthelmintics. INVERTEBRATE NEUROSCIENCE : IN 2012; 12:37-41. [PMID: 22562659 PMCID: PMC3889471 DOI: 10.1007/s10158-012-0135-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Accepted: 04/18/2012] [Indexed: 12/21/2022]
Abstract
Crystal (Cry) proteins are made by the Gram-positive bacterium Bacillus thuringiensis (Bt). Cry proteins are pore-forming proteins and are the most widely used biological insecticides in the world. Our laboratory found some Cry proteins are highly effective against a broad range of nematodes (roundworms). Here, we discuss our results of Cry protein activity against intestinal roundworms. Both Cry5B and Cry21A have therapeutic activities against infections of the roundworm Heligmosomoides polygyrus bakeri in mice. Cry5B also shows highly therapeutic activity against Ancylostoma ceylanicum infection in hamsters. A. ceylanicum is a minor hookworm parasite of humans, and it is closely related to the more prevalent Ancylostoma duodenale. In addition, Cry proteins show excellent combinatorial therapeutic properties with nicotinic acetylcholine receptor (nAChR) agonists, one of the two classes of compounds approved by the World Health Organization for the treatment for intestinal roundworms in humans. Given their non-toxicity to humans and their broad spectrum of nematicidal action, Cry proteins show great potential as next-generation anthelmintics.
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Affiliation(s)
- Yan Hu
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, Mail Code 0322, La Jolla, CA 92093-0322, USA
| | - Raffi V. Aroian
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, Mail Code 0322, La Jolla, CA 92093-0322, USA
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Ryffel GU. Dismay with GM maize. A science-based solution to public resistance against genetically modified crops that could be compatible with organic farming. EMBO Rep 2011; 12:996-9. [PMID: 21909075 DOI: 10.1038/embor.2011.182] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 08/24/2011] [Indexed: 01/20/2023] Open
Affiliation(s)
- Gerhart U Ryffel
- Institute for Cell Biology, University Hospital Essen, University Duisburg-Essen, Germany.
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Cohen S, Albeck S, Ben-Dov E, Cahan R, Firer M, Zaritsky A, Dym O. Cyt1Aa toxin: crystal structure reveals implications for its membrane-perforating function. J Mol Biol 2011; 413:804-14. [PMID: 21959261 DOI: 10.1016/j.jmb.2011.09.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 09/09/2011] [Accepted: 09/13/2011] [Indexed: 10/17/2022]
Abstract
During sporulation, Bacillus thuringiensis subsp. israelensis produces a mosquito larvicidal protein complex containing several crystalline and cytolytic (Cyt) toxins. Here, the activated monomeric form of Cyt1Aa, the most toxic Cyt family member, was isolated and crystallized, and its structure was determined for the first time at 2.2 Å resolution. Cyt1Aa adopts a typical cytolysin fold containing a β-sheet held by two surrounding α-helical layers. The absence of a β-strand (between residues V26 and I37) in the dimeric structure of Cyt2Aa led us to deduce that this is the only essential segment for dimer formation and that activation of the toxin occurs by proteolytic processing of its N-terminus. Based on the Cyt1Aa structure, we suggest that the toxicity of Cyt1Aa and other nonrelated proteins, all sharing a cytolysin fold, is correlated with their ability to undergo conformational changes that are necessary prior to their membrane insertion and perforation. This fold allows the α-helical layers to swing away, exposing the β-sheet to insert into the membrane. The identification of a putative lipid binding pocket between the β-sheet and the helical layer of Cyt1Aa supports this mechanism. Sequence-based structural analysis of Cyt1Aa revealed that the lack of activity of Cyt1Ca may be related to the latter's inability to undergo this conformational change due to its lack of flexibility. The pattern of the hemolytic activity of Cyt1Aa presented here (resembling that of pore-forming agents), while differing from that imposed by ionic and nonionic detergents, further supports the pore-forming model by which conformational changes occur prior to membrane insertion and perforation.
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Affiliation(s)
- Shmuel Cohen
- Department of Life Sciences, Ben-Gurion University of the Negev, Be'er-Sheva 84105, Israel
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Porta H, Jiménez G, Cordoba E, León P, Soberón M, Bravo A. Tobacco plants expressing the Cry1AbMod toxin suppress tolerance to Cry1Ab toxin of Manduca sexta cadherin-silenced larvae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:513-9. [PMID: 21621616 DOI: 10.1016/j.ibmb.2011.04.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 04/15/2011] [Accepted: 04/25/2011] [Indexed: 05/30/2023]
Abstract
Cry toxins produced by Bacillus thuringiensis bacteria are insecticidal proteins used worldwide in the control of different insect pests. Alterations in toxin-receptor interaction represent the most common mechanism to induce resistance to Cry toxins in lepidopteran insects. Cry toxins bind with high affinity to the cadherin protein present in the midgut cells and this interaction facilitates the proteolytic removal of helix α-1 and pre-pore oligomer formation. Resistance to Cry toxins has been linked with mutations in the cadherin gene. One strategy effective to overcome larval resistance to Cry1A toxins is the production of Cry1AMod toxins that lack helix α-1. Cry1AMod are able to form oligomeric structures without binding to cadherin receptor and were shown to be toxic to cadherin-silenced Manduca sexta larvae and Pectinophora gossypiella strain with resistance linked to mutations in a cadherin gene. We developed Cry1AbMod tobacco transgenic plants to analyze if Cry1AMod toxins can be expressed in transgenic crops, do not affect plant development and are able to control insect pests. Our results show that production of the Cry1AbMod toxin in transgenic plants does not affect plant development, since these plants exhibited healthy growth, produced abundant seeds, and were virtually undistinguishable from control plants. Most importantly, Cry1AbMod protein produced in tobacco plants retains its functional toxic activity against susceptible and tolerant M. sexta larvae due to the silencing of cadherin receptor by RNAi. These results suggest that CryMod toxins could potentially be expressed in other transgenic crops to protect them against both toxin-susceptible and resistant lepidopteran larvae affected in cadherin gene.
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Affiliation(s)
- Helena Porta
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca, Morelos 62250, Mexico.
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