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Miranda LS, Rudd SR, Mena O, Hudspeth PE, Barboza-Corona JE, Park HW, Bideshi DK. The Perpetual Vector Mosquito Threat and Its Eco-Friendly Nemeses. BIOLOGY 2024; 13:182. [PMID: 38534451 DOI: 10.3390/biology13030182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 03/28/2024]
Abstract
Mosquitoes are the most notorious arthropod vectors of viral and parasitic diseases for which approximately half the world's population, ~4,000,000,000, is at risk. Integrated pest management programs (IPMPs) have achieved some success in mitigating the regional transmission and persistence of these diseases. However, as many vector-borne diseases remain pervasive, it is obvious that IPMP successes have not been absolute in eradicating the threat imposed by mosquitoes. Moreover, the expanding mosquito geographic ranges caused by factors related to climate change and globalization (travel, trade, and migration), and the evolution of resistance to synthetic pesticides, present ongoing challenges to reducing or eliminating the local and global burden of these diseases, especially in economically and medically disadvantaged societies. Abatement strategies include the control of vector populations with synthetic pesticides and eco-friendly technologies. These "green" technologies include SIT, IIT, RIDL, CRISPR/Cas9 gene drive, and biological control that specifically targets the aquatic larval stages of mosquitoes. Regarding the latter, the most effective continues to be the widespread use of Lysinibacillus sphaericus (Ls) and Bacillus thuringiensis subsp. israelensis (Bti). Here, we present a review of the health issues elicited by vector mosquitoes, control strategies, and lastly, focus on the biology of Ls and Bti, with an emphasis on the latter, to which no resistance has been observed in the field.
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Affiliation(s)
- Leticia Silva Miranda
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Sarah Renee Rudd
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Integrated Biomedical Graduate Studies, and School of Medicine, Loma Linda University, Loma Linda, CA 92350, USA
| | - Oscar Mena
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Piper Eden Hudspeth
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - José E Barboza-Corona
- Departmento de Alimentos, Posgrado en Biociencias, Universidad de Guanajuato Campus Irapuato-Salamanca, Irapuato 36500, Guanajuato, Mexico
| | - Hyun-Woo Park
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Dennis Ken Bideshi
- Graduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
- Undergraduate Program in Biomedical Sciences, Department of Biological Sciences, California Baptist University, Riverside, CA 92504, USA
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Takahashi H, Asakura M, Ide T, Hayakawa T. Mutational analysis of the transmembrane α4-helix of Bacillus thuringiensis mosquito-larvicidal Cry4Aa toxin. Curr Microbiol 2024; 81:80. [PMID: 38281302 PMCID: PMC10822788 DOI: 10.1007/s00284-023-03602-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 12/26/2023] [Indexed: 01/30/2024]
Abstract
Cry4Aa, produced by Bacillus thuringiensis subsp. israelensis, exhibits specific toxicity to larvae of medically important mosquito genera. Cry4Aa functions as a pore-forming toxin, and a helical hairpin (α4-loop-α5) of domain I is believed to be the transmembrane domain that forms toxin pores. Pore formation is considered to be a central mode of Cry4Aa action, but the relationship between pore formation and toxicity is poorly understood. In the present study, we constructed Cry4Aa mutants in which each polar amino acid residues within the transmembrane α4 helix was replaced with glutamic acid. Bioassays using Culex pipiens mosquito larvae and subsequent ion permeability measurements using symmetric KCl solution revealed an apparent correlation between toxicity and toxin pore conductance for most of the Cry4Aa mutants. In contrast, the Cry4Aa mutant H178E was a clear exception, almost losing its toxicity but still exhibiting a moderately high conductivity of about 60% of the wild-type. Furthermore, the conductance of the pore formed by the N190E mutant (about 50% of the wild-type) was close to that of H178E, but the toxicity was significantly higher than that of H178E. Ion selectivity measurements using asymmetric KCl solution revealed a significant decrease in cation selectivity of toxin pores formed by H178E compared to N190E. Our data suggest that the toxicity of Cry4Aa is primarily pore related. The formation of toxin pores that are highly ion-permeable and also highly cation-selective may enhance the influx of cations and water into the target cell, thereby facilitating the eventual death of mosquito larvae.
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Affiliation(s)
- Hirokazu Takahashi
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama, 700-8530, Japan
| | - Mami Asakura
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama, 700-8530, Japan
| | - Toru Ide
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama, 700-8530, Japan
| | - Tohru Hayakawa
- Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, 3-1-1 Tsushima-Naka, Kita-Ku, Okayama, 700-8530, Japan.
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He X, Yang Y, Soberón M, Bravo A, Zhang L, Zhang J, Wang Z. Bacillus thuringiensis Cry9Aa Insecticidal Protein Domain I Helices α3 and α4 Are Two Core Regions Involved in Oligomerization and Toxicity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:1321-1329. [PMID: 38175929 DOI: 10.1021/acs.jafc.3c08070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
Bacillus thuringiensis Cry9 proteins show high insecticidal activity against different lepidopteran pests. Cry9 could be a valuable alternative to Cry1 proteins because it showed a synergistic effect with no cross-resistance. However, the pore-formation region of the Cry9 proteins is still unclear. In this study, nine mutations of certain Cry9Aa helices α3 and α4 residues resulted in a complete loss of insecticidal activity against the rice pest Chilo suppressalis; however, the protein stability and receptor binding ability of these mutants were not affected. Among these mutants, Cry9Aa-D121R, Cry9Aa-D125R, Cry9Aa-D163R, Cry9Aa-E165R, and Cry9Aa-D167R are unable to form oligomers in vitro, while the oligomers formed by Cry9Aa-R156D, Cry9Aa-R158D, and Cry9Aa-R160D are unstable and failed to insert into the membrane. These data confirmed that helices α3 and α4 of Cry9Aa are involved in oligomerization, membrane insertion, and toxicity. The knowledge of Cry9 pore-forming action may promote its application as an alternative to Cry1 insecticidal proteins.
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Affiliation(s)
- Xiang He
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui Province 230036, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Yanchao Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Mario Soberón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Apdo. Postal 510-3, Morelos 62250, Mexico
| | - Alejandra Bravo
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Apdo. Postal 510-3, Morelos 62250, Mexico
| | - Lihong Zhang
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui Province 230036, China
| | - Jie Zhang
- Anhui Province Engineering Laboratory for Green Pesticide Development and Application, School of Plant Protection, Anhui Agricultural University, Hefei, Anhui Province 230036, China
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Zeyu Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Torres J, Surya W, Boonserm P. Channel Formation in Cry Toxins: An Alphafold-2 Perspective. Int J Mol Sci 2023; 24:16809. [PMID: 38069132 PMCID: PMC10705909 DOI: 10.3390/ijms242316809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 12/18/2023] Open
Abstract
Bacillus thuringiensis (Bt) strains produce pore-forming toxins (PFTs) that attack insect pests. Information for pre-pore and pore structures of some of these Bt toxins is available. However, for the three-domain (I-III) crystal (Cry) toxins, the most used Bt toxins in pest control, this crucial information is still missing. In these Cry toxins, biochemical data have shown that 7-helix domain I is involved in insertion in membranes, oligomerization and formation of a channel lined mainly by helix α4, whereas helices α1 to α3 seem to have a dynamic role during insertion. In the case of Cry1Aa, toxic against Manduca sexta larvae, a tetrameric oligomer seems to precede membrane insertion. Given the experimental difficulty in the elucidation of the membrane insertion steps, we used Alphafold-2 (AF2) to shed light on possible oligomeric structural intermediates in the membrane insertion of this toxin. AF2 very accurately (<1 Å RMSD) predicted the crystal monomeric and trimeric structures of Cry1Aa and Cry4Ba. The prediction of a tetramer of Cry1Aa, but not Cry4Ba, produced an 'extended model' where domain I helices α3 and α2b form a continuous helix and where hydrophobic helices α1 and α2 cluster at the tip of the bundle. We hypothesize that this represents an intermediate that binds the membrane and precedes α4/α5 hairpin insertion, together with helices α6 and α7. Another Cry1Aa tetrameric model was predicted after deleting helices α1 to α3, where domain I produced a central cavity consistent with an ion channel, lined by polar and charged residues in helix α4. We propose that this second model corresponds to the 'membrane-inserted' structure. AF2 also predicted larger α4/α5 hairpin n-mers (14 ≤n ≤ 17) with high confidence, which formed even larger (~5 nm) pores. The plausibility of these models is discussed in the context of available experimental data and current paradigms.
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Affiliation(s)
- Jaume Torres
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Panadda Boonserm
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand;
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Prashar A, Kinkar OU, Kumar A, Hadapad AB, Makde RD, Hire RS. Crystal structures of PirA and PirB toxins from Photorhabdus akhurstii subsp. akhurstii K-1. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2023; 162:104014. [PMID: 37778713 DOI: 10.1016/j.ibmb.2023.104014] [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: 06/02/2023] [Revised: 08/08/2023] [Accepted: 09/25/2023] [Indexed: 10/03/2023]
Abstract
PirAB binary toxin from Photorhabdus is toxic to the larvae of dipteran and lepidopteran insect pests. However, the 3-D structures and their toxicity mechanism are not yet fully understood. Here we report the crystal structures of PirA and PirB proteins from Photorhabdus akhurstii subsp. akhurstii K-1 at 1.6 and 2.1 Å, respectively. PirA comprises of eight β-strands depicting jelly-roll topology while PirB folds into two distinct domains, an N-terminal domain (PirB-N) made up of seven α-helices and a C-terminal domain (PirB-C) consists of ten β-strands. Despite the low sequence identity, PirA adopts similar architecture as domain III and PirB shared similar architecture as domain I/II of the Cry δ-endotoxin of Bacillus thuringiensis, respectively. However, PirA shows significant structural variations as compared to domain III of lepidopteran and dipteran specific Cry toxins (Cry1Aa and Cry11Ba) suggesting its role in virulence among range of insect pests and hence, in receptor binding. High structural resemblance between PirB-N and domain I of Cry toxin raises the possibility that the putative PirAB binary toxin may mimic the toxicity mechanism of the Cry protein, particularly its ability to perform pore formation. The mixture of independently purified PirA and PirB proteins are not toxic to insects. However, PirA-PirB protein complex purified from expression of pir operon with non-coding Enterobacterial Repetitive Intergenic Consensus (ERIC) sequences found toxic to Galleria mellonella larvae with LD50 value of 1.62 μg/larva. This suggests that toxic conformation of PirA and PirB are achieved in-vivo with the help of ERIC sequences.
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Affiliation(s)
- Arpit Prashar
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Omkar U Kinkar
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashwani Kumar
- Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ashok B Hadapad
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ravindra D Makde
- Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India; Beamline Development and Application Section, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India.
| | - Ramesh S Hire
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai, 400085, Maharashtra, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, 400094, Maharashtra, India.
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Thammasittirong A, Thammasittirong SNR. Cry4Ba toxin of Bacillus thuringiensis subsp. israelensis uses both domains II and III to bind to its receptor- Aedes aegypti alkaline phosphatase. Heliyon 2023; 9:e19458. [PMID: 37810109 PMCID: PMC10558600 DOI: 10.1016/j.heliyon.2023.e19458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 08/19/2023] [Accepted: 08/23/2023] [Indexed: 10/10/2023] Open
Abstract
Receptor binding is one of the crucial steps to exhibit the insecticidal activity of Cry toxins. In addition, binding to receptors is a determining step for the specificity of toxins. In this work, receptor binding domain II was cloned from the full-length Cry4Ba toxin and heterologously expressed in Escherichia coli. The 21 kDa purified protein was characterized as Cry4Ba domain II using Western blotting and tandem mass spectrometry coupled to liquid chromatography. Circular dichroism revealed the correct folding of the isolated domain II fragment, similar to that found in the Cry4Ba protein. Binding analysis using an enzyme-linked immunosorbent assay revealed that the purified Cry4Ba-domain II had bound to the 54 kDa alkaline phosphatase cloned from Aedes aegypti (Aa-mALP) with a dissociation constant of approximately 116.27 ± 11.09 nM. The binding affinity of Cry4Ba-domain II to Aa-mALP was comparable to that of Cry4Ba domain III, suggesting that both domains II and III of the Cry4Ba contributed equally in binding to the Aa-mALP protein. Our findings should provide more valuable insight on the molecular mechanisms in the toxin-receptor interaction of the Cry4Ba toxin.
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Affiliation(s)
- Anon Thammasittirong
- Department of Science and Bioinnovation, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom, 73140, Thailand
- Microbial Biotechnology Unit, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom, 73140, Thailand
| | - Sutticha Na Ranong Thammasittirong
- Department of Science and Bioinnovation, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom, 73140, Thailand
- Microbial Biotechnology Unit, Faculty of Liberal Arts and Science, Kasetsart University, Nakhon Pathom, 73140, Thailand
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Pacheco S, Gómez I, Peláez-Aguilar AE, Verduzco-Rosas LA, García-Suárez R, do Nascimento NA, Rivera-Nájera LY, Cantón PE, Soberón M, Bravo A. Structural changes upon membrane insertion of the insecticidal pore-forming toxins produced by Bacillus thuringiensis. FRONTIERS IN INSECT SCIENCE 2023; 3:1188891. [PMID: 38469496 PMCID: PMC10926538 DOI: 10.3389/finsc.2023.1188891] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 04/04/2023] [Indexed: 03/13/2024]
Abstract
Different Bacillus thuringiensis (Bt) strains produce a broad variety of pore-forming toxins (PFTs) that show toxicity against insects and other invertebrates. Some of these insecticidal PFT proteins have been used successfully worldwide to control diverse insect crop pests. There are several studies focused on describing the mechanism of action of these toxins that have helped to improve their performance and to cope with the resistance evolved by different insects against some of these proteins. However, crucial information that is still missing is the structure of pores formed by some of these PFTs, such as the three-domain crystal (Cry) proteins, which are the most commercially used Bt toxins in the biological control of insect pests. In recent years, progress has been made on the identification of the structural changes that certain Bt insecticidal PFT proteins undergo upon membrane insertion. In this review, we describe the models that have been proposed for the membrane insertion of Cry toxins. We also review the recently published structures of the vegetative insecticidal proteins (Vips; e.g. Vip3) and the insecticidal toxin complex (Tc) in the membrane-inserted state. Although different Bt PFTs show different primary sequences, there are some similarities in the three-dimensional structures of Vips and Cry proteins. In addition, all PFTs described here must undergo major structural rearrangements to pass from a soluble form to a membrane-inserted state. It is proposed that, despite their structural differences, all PFTs undergo major structural rearrangements producing an extended α-helix, which plays a fundamental role in perforating their target membrane, resulting in the formation of the membrane pore required for their insecticidal activity.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
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Ma X, Hu J, Ding C, Portieles R, Xu H, Gao J, Du L, Gao X, Yue Q, Zhao L, Borrás-Hidalgo O. New native Bacillus thuringiensis strains induce high insecticidal action against Culex pipiens pallens larvae and adults. BMC Microbiol 2023; 23:100. [PMID: 37055727 PMCID: PMC10099900 DOI: 10.1186/s12866-023-02842-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 03/28/2023] [Indexed: 04/15/2023] Open
Abstract
Mosquitoes of many species are key disease vectors, killing millions of people each year. Bacillus thuringiensis-based insecticide formulations are largely recognized as among the most effective, ecologically safe, and long-lasting methods of managing insect pests. New B. thuringiensis strains with high mosquito control effectiveness were isolated, identified, genetically defined, and physiologically characterized. Eight B. thuringiensis strains were identified and shown to carry endotoxin-producing genes. Using a scanning electron microscope, results revealed typical crystal forms of various shapes in B. thuringiensis strains. Fourteen cry and cyt genes were found in the strains examined. Although the genome of the B. thuringiensis A4 strain had twelve cry and cyt genes, not all of them were expressed, and only a few protein profiles were observed. The larvicidal activity of the eight B. thuringiensis strains was found to be positive (LC50: 1.4-28.5 g/ml and LC95: 15.3-130.3 g/ml). Bioassays in a laboratory environment demonstrated that preparations containing B. thuringiensis spores and crystals were particularly active to mosquito larvae and adults. These new findings show that the novel preparation containing B. thuringiensis A4 spores and crystals mixture might be used to control larval and adult mosquitoes in a sustainable and ecologically friendly manner.
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Affiliation(s)
- Xinmin Ma
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Jianjian Hu
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Chengsong Ding
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Roxana Portieles
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Hongli Xu
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Jingyao Gao
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Lihua Du
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Xiangyou Gao
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China
| | - Qiulin Yue
- State Key Laboratory of Biobased Material and Green Papermaking, Shandong Provincial Key Lab of Microbial Engineering, Qilu University of Technology (Shandong Academic of Science), Jinan, People's Republic of China
| | - Lin Zhao
- State Key Laboratory of Biobased Material and Green Papermaking, Shandong Provincial Key Lab of Microbial Engineering, Qilu University of Technology (Shandong Academic of Science), Jinan, People's Republic of China
| | - Orlando Borrás-Hidalgo
- Joint R and D Center of Biotechnology, RETDA, Yotabio-Engineering Co., Ltd, 99 Shenzhen Road, Rizhao, 276826, Shandong, People's Republic of China.
- State Key Laboratory of Biobased Material and Green Papermaking, Shandong Provincial Key Lab of Microbial Engineering, Qilu University of Technology (Shandong Academic of Science), Jinan, People's Republic of China.
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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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Aromatic Residues on the Side Surface of Cry4Ba-Domain II of Bacillus thuringiensis subsp. israelensis Function in Binding to Their Counterpart Residues on the Aedes aegypti Alkaline Phosphatase Receptor. Toxins (Basel) 2023; 15:toxins15020114. [PMID: 36828427 PMCID: PMC9960242 DOI: 10.3390/toxins15020114] [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: 12/28/2022] [Revised: 01/22/2023] [Accepted: 01/26/2023] [Indexed: 01/31/2023] Open
Abstract
Receptor binding is a prerequisite process to exert the mosquitocidal activity of the Cry4Ba toxin of Bacillus thuringiensis subsp. israelensis. The beta-sheet prism (domain II) and beta-sheet sandwich (domain III) of the Cry4Ba toxin have been implicated in receptor binding, albeit the precise binding mechanisms of these remain unclear. In this work, alanine scanning was used to determine the contribution to receptor binding of some aromatic and hydrophobic residues on the surface of domains II and III that are predicted to be responsible for binding to the Aedes aegypti membrane-bound alkaline phosphatase (Aa-mALP) receptor. Larvicidal activity assays against A. aegypti larvae revealed that aromatic residues (Trp327 on the β2 strand, Tyr347 on the β3-β4 loop, and Tyr359 on the β4 strand) of domain II were important to the toxicity of the Cry4Ba toxin. Quantitative binding assays using enzyme-linked immunosorbent assay (ELISA) showed similar decreasing trends in binding to the Aa-mALP receptor and in toxicity of the Cry4Ba mutants Trp327Ala, Tyr347Ala, and Tyr359Ala, suggesting that a possible function of these surface-exposed aromatic residues is receptor binding. In addition, binding assays of the Cry4Ba toxin to the mutants of the binding residues Gly513, Ser490, and Phe497 of the Aa-mALP receptor supported the binding function of Trp327, Tyr347, and Tyr359 of the Cry4Ba toxin, respectively. Altogether, our results showed for the first time that aromatic residues on a side surface of the Cry4Ba domain II function in receptor binding. This finding provides greater insight into the possible molecular mechanisms of the Cry4Ba toxin.
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Pacheco S, Gómez I, Soberón M, Bravo A. A major conformational change of N-terminal helices of Bacillus thuringiensis Cry1Ab insecticidal protein is necessary for membrane insertion and toxicity. FEBS J 2022; 290:2692-2705. [PMID: 36560841 DOI: 10.1111/febs.16710] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 12/01/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
Pore forming toxins rely on oligomerization for membrane insertion to kill their targets. Bacillus thuringiensis produces insecticidal Cry-proteins composed of three domains that form pores that kill the insect larvae. Domain I is involved in oligomerization and membrane insertion, whereas Domains II and III participate in receptor binding and specificity. However, the structural changes involved in membrane insertion of these proteins remain unsolved. The most widely accepted model for membrane insertion, the 'umbrella model', proposed that the α-4/α-5 hairpin of Domain I swings away and is inserted into the membrane. To determine the topology of Cry1Ab in the membrane, disulfide bonds linking α-helices of Domain I were introduced to restrict their movement. Disulfide bonds between helices α-2/α-3 or α-3/α-4 lost oligomerization and toxicity, indicating that movement of these helices is needed for insecticidal activity. By contrast, disulfide bonds linking helices α-5/α-6 did not affect toxicity, which contradicts the 'umbrella model'. Additionally, Föster resonance energy transfer closest approach analyses measuring distances of different points in the toxin to the membrane plane and collisional quenching assays analysing the protection of specific fluorescent-labeled residues to the soluble potassium iodide quencher in the membrane inserted state were performed. Overall, the data show that Domain I from Cry1Ab may undergo a major conformational change during its membrane insertion, where the N-terminal region (helices α-1 to α-4) participates in oligomerization and toxicity, probably forming an extended helix. These data break a paradigm, showing a new 'folding white-cane model', which better explains the structural changes of Cry toxins during insertion into the membrane.
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Affiliation(s)
- Sabino Pacheco
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Isabel Gómez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Mario Soberón
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
| | - Alejandra Bravo
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
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12
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Insights from the Structure of an Active Form of Bacillus thuringiensis Cry5B. Toxins (Basel) 2022; 14:toxins14120823. [PMID: 36548720 PMCID: PMC9785347 DOI: 10.3390/toxins14120823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/17/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022] Open
Abstract
The crystal protein Cry5B, a pore-forming protein produced by the soil bacterium Bacillus thuringiensis, has been demonstrated to have excellent anthelmintic activity. While a previous structure of the three-domain core region of Cry5B(112-698) had been reported, this structure lacked a key N-terminal extension critical to function. Here we report the structure of Cry5B(27-698) containing this N-terminal extension. This new structure adopts a distinct quaternary structure compared to the previous Cry5B(112-698) structure, and also exhibits a change in the conformation of residues 112-140 involved in linking the N-terminal extension to the three-domain core by forming a random coil and an extended α-helix. A role for the N-terminal extension is suggested based on a computational model of the tetramer with the conformation of residues 112-140 in its alternate α-helix conformation. Finally, based on the Cry5B(27-698) structure, site-directed mutagenesis studies were performed on Tyr495, which revealed that having an aromatic group or bulky group at this residue 495 is important for Cry5B toxicity.
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13
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Complete structure elucidation of a functional form of the Bacillus thuringiensis Cry4Ba δ-endotoxin: Insights into toxin-induced transmembrane pore architecture. Biochem Biophys Res Commun 2022; 620:158-164. [DOI: 10.1016/j.bbrc.2022.06.065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 06/21/2022] [Indexed: 11/24/2022]
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14
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Tetreau G, Sawaya MR, De Zitter E, Andreeva EA, Banneville AS, Schibrowsky NA, Coquelle N, Brewster AS, Grünbein ML, Kovacs GN, Hunter MS, Kloos M, Sierra RG, Schiro G, Qiao P, Stricker M, Bideshi D, Young ID, Zala N, Engilberge S, Gorel A, Signor L, Teulon JM, Hilpert M, Foucar L, Bielecki J, Bean R, de Wijn R, Sato T, Kirkwood H, Letrun R, Batyuk A, Snigireva I, Fenel D, Schubert R, Canfield EJ, Alba MM, Laporte F, Després L, Bacia M, Roux A, Chapelle C, Riobé F, Maury O, Ling WL, Boutet S, Mancuso A, Gutsche I, Girard E, Barends TRM, Pellequer JL, Park HW, Laganowsky AD, Rodriguez J, Burghammer M, Shoeman RL, Doak RB, Weik M, Sauter NK, Federici B, Cascio D, Schlichting I, Colletier JP. De novo determination of mosquitocidal Cry11Aa and Cry11Ba structures from naturally-occurring nanocrystals. Nat Commun 2022; 13:4376. [PMID: 35902572 PMCID: PMC9334358 DOI: 10.1038/s41467-022-31746-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/30/2022] [Indexed: 11/08/2022] Open
Abstract
Cry11Aa and Cry11Ba are the two most potent toxins produced by mosquitocidal Bacillus thuringiensis subsp. israelensis and jegathesan, respectively. The toxins naturally crystallize within the host; however, the crystals are too small for structure determination at synchrotron sources. Therefore, we applied serial femtosecond crystallography at X-ray free electron lasers to in vivo-grown nanocrystals of these toxins. The structure of Cry11Aa was determined de novo using the single-wavelength anomalous dispersion method, which in turn enabled the determination of the Cry11Ba structure by molecular replacement. The two structures reveal a new pattern for in vivo crystallization of Cry toxins, whereby each of their three domains packs with a symmetrically identical domain, and a cleavable crystal packing motif is located within the protoxin rather than at the termini. The diversity of in vivo crystallization patterns suggests explanations for their varied levels of toxicity and rational approaches to improve these toxins for mosquito control.
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Affiliation(s)
- Guillaume Tetreau
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Michael R Sawaya
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, CA, 90095-1570, USA
| | - Elke De Zitter
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Elena A Andreeva
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Anne-Sophie Banneville
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Natalie A Schibrowsky
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, CA, 90095-1570, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Nicolas Coquelle
- Large-Scale Structures Group, Institut Laue-Langevin, F-38000, Grenoble, France
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Marie Luise Grünbein
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Gabriela Nass Kovacs
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Mark S Hunter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Marco Kloos
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Raymond G Sierra
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Giorgio Schiro
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Pei Qiao
- Department of Chemistry, Texas A&M University, College Station, TX, 77845, USA
| | - Myriam Stricker
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Dennis Bideshi
- Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
- Department of Biological Sciences, California Baptist University, Riverside, CA, 92504, USA
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ninon Zala
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Sylvain Engilberge
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Alexander Gorel
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Luca Signor
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Jean-Marie Teulon
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Mario Hilpert
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Lutz Foucar
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Johan Bielecki
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Richard Bean
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Raphael de Wijn
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Tokushi Sato
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Henry Kirkwood
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Romain Letrun
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Alexander Batyuk
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Irina Snigireva
- European Synchrotron Radiation Facility (ESRF), BP 220, 38043, Grenoble, France
| | - Daphna Fenel
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Robin Schubert
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Ethan J Canfield
- Mass Spectrometry Core Facility, School of Pharmacy, University of Southern California, Los Angeles, CA, 90089, USA
| | - Mario M Alba
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, 90089, USA
| | | | | | - Maria Bacia
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Amandine Roux
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342, Lyon, France
| | | | - François Riobé
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342, Lyon, France
| | - Olivier Maury
- Univ. Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342, Lyon, France
| | - Wai Li Ling
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Sébastien Boutet
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA
| | - Adrian Mancuso
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - Irina Gutsche
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Eric Girard
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Thomas R M Barends
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Jean-Luc Pellequer
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Hyun-Woo Park
- Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
- Department of Biological Sciences, California Baptist University, Riverside, CA, 92504, USA
| | - Arthur D Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX, 77845, USA
| | - Jose Rodriguez
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, CA, 90095-1570, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095, USA
| | - Manfred Burghammer
- European Synchrotron Radiation Facility (ESRF), BP 220, 38043, Grenoble, France
| | - Robert L Shoeman
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - R Bruce Doak
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Martin Weik
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Brian Federici
- Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Duilio Cascio
- UCLA-DOE Institute for Genomics and Proteomics, Department of Biological Chemistry, University of California, Los Angeles, CA, 90095-1570, USA
| | - Ilme Schlichting
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120, Heidelberg, Germany
| | - Jacques-Philippe Colletier
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 71 Avenue des martyrs, F-38000, Grenoble, France.
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15
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Alam I, Batool K, Idris AL, Tan W, Guan X, Zhang L. Role of Lectin in the Response of Aedes aegypti Against Bt Toxin. Front Immunol 2022; 13:898198. [PMID: 35634312 PMCID: PMC9136036 DOI: 10.3389/fimmu.2022.898198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 04/19/2022] [Indexed: 12/05/2022] Open
Abstract
Aedes aegypti is one of the world’s most dangerous mosquitoes, and a vector of diseases such as dengue fever, chikungunya virus, yellow fever, and Zika virus disease. Currently, a major global challenge is the scarcity of antiviral medicine and vaccine for arboviruses. Bacillus thuringiensis var israelensis (Bti) toxins are used as biological mosquito control agents. Endotoxins, including Cry4Aa, Cry4Ba, Cry10Aa, Cry11Aa, and Cyt1Aa, are toxic to mosquitoes. Insect eradication by Cry toxin relies primarily on the interaction of cry toxins with key toxin receptors, such as aminopeptidase (APN), alkaline phosphatase (ALP), cadherin (CAD), and ATP-binding cassette transporters. The carbohydrate recognition domains (CRDs) of lectins and domains II and III of Cry toxins share similar structural folds, suggesting that midgut proteins, such as C-type lectins (CTLs), may interfere with interactions among Cry toxins and receptors by binding to both and alter Cry toxicity. In the present review, we summarize the functional role of C-type lectins in Ae. aegypti mosquitoes and the mechanism underlying the alteration of Cry toxin activity by CTLs. Furthermore, we outline future research directions on elucidating the Bti resistance mechanism. This study provides a basis for understanding Bti resistance, which can be used to develop novel insecticides.
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Affiliation(s)
- Intikhab Alam
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Lab of Biopesticides and Chemical Biology, MOE, Fujian Agriculture and Forestry University, Fuzhou, China
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Khadija Batool
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Lab of Biopesticides and Chemical Biology, MOE, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Aisha Lawan Idris
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Lab of Biopesticides and Chemical Biology, MOE, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Weilong Tan
- Nanjing Bioengineering (Gene) Technology Center for Medicines, Nanjing, China
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Lab of Biopesticides and Chemical Biology, MOE, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Lingling Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
- Key Lab of Biopesticides and Chemical Biology, MOE, Fujian Agriculture and Forestry University, Fuzhou, China
- *Correspondence: Lingling Zhang,
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16
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Gonzalez-Vazquez MC, Vela-Sanchez RA, Rojas-Ruiz NE, Carabarin-Lima A. Importance of Cry Proteins in Biotechnology: Initially a Bioinsecticide, Now a Vaccine Adjuvant. Life (Basel) 2021; 11:999. [PMID: 34685371 PMCID: PMC8541582 DOI: 10.3390/life11100999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 09/19/2021] [Accepted: 09/19/2021] [Indexed: 11/21/2022] Open
Abstract
A hallmark of Bacillus thuringiensis bacteria is the formation of one or more parasporal crystal (Cry) proteins during sporulation. The toxicity of these proteins is highly specific to insect larvae, exerting lethal effects in different insect species but not in humans or other mammals. The aim of this review is to summarize previous findings on Bacillus thuringiensis, including the characteristics of the bacterium, its subsequent contribution to biotechnology as a bioinsecticide due to the presence of Cry proteins, and its potential application as an adjuvant. In several studies, Cry proteins have been administered together with specific antigens to immunize experimental animal models. The results have shown that these proteins can enhance immunogenicity by generating an adequate immune response capable of protecting the model against an experimental infectious challenge, whereas protection is decreased when the specific antigen is administered without the Cry protein. Therefore, based on previous results and the structural homology between Cry proteins, these molecules have arisen as potential adjuvants in the development of vaccines for both animals and humans. Finally, a model of the interaction of Cry proteins with different components of the immune response is proposed.
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Affiliation(s)
- Maria Cristina Gonzalez-Vazquez
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
| | - Ruth Abril Vela-Sanchez
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
| | - Norma Elena Rojas-Ruiz
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
| | - Alejandro Carabarin-Lima
- Centro de Investigaciones en Ciencias Microbiologicas, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico; (M.C.G.-V.); (N.E.R.-R.)
- Licenciatura en Biotecnología, Benemerita Universidad Autonoma de Puebla, Puebla 72000, PU, Mexico;
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17
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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: 45] [Impact Index Per Article: 15.0] [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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18
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Bourchookarn W, Bourchookarn A, Imtong C, Li HC, Angsuthanasombat C. His 180 in the pore-lining α4 of the Bacillus thuringiensis Cry4Aa δ-endotoxin is crucial for structural arrangements of the α4-α5 transmembrane hairpin and hence biotoxicity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2021; 1869:140634. [PMID: 33636413 DOI: 10.1016/j.bbapap.2021.140634] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/15/2021] [Accepted: 02/19/2021] [Indexed: 10/22/2022]
Abstract
One proposed toxic mechanism of Bacillus thuringiensis Cry δ-endotoxins involves pore formation in target membranes by the α4-α5 transmembrane hairpin constituting their pore-forming domain. Here, nine selected charged and uncharged polar residues in the pore-lining α4 of the Cry4Aa mosquito-active toxin were substituted with Ala. All mutant toxins, i.e., D169A, R171A, Q173A, H178A, Y179A, H180A, Q182A, N183A and E187A, were over-expressed in Escherichia coli as 130-kDa protoxin inclusions at levels comparable to the wild-type toxin. Bioassays against Aedes aegypti larvae revealed that only H178A and H180A mutants displayed a drastic reduction in biotoxicity, albeit almost complete insolubility observed for H178A, but not for H180A inclusions. Further mutagenic analysis showed that replacements of His180 with charged (Arg, Lys, Asp, Glu), small uncharged polar (Ser, Cys) or small non-polar (Gly, Val) residues severely impaired the biotoxicity, unlike substitutions with relatively large uncharged (Asn, Gln, Leu) or aromatic (Phe, Tyr, Trp) residues. Similar to the trypsin-activated wild-type toxin, both bio-active and -inactive H180 mutants were still capable of releasing entrapped calcein from lipid vesicles and producing cation-selective channels with ~130-pS maximum conductance. Analysis of the Cry4Aa structure revealed the existence of a hydrophobic cavity near the critical His180 side-chain. Analysis of simulated structures revealed that His180-to-smaller residue conversions create a gap disrupting such cavity's hydrophobicity and hence structural arrangements of the α4-α5 hairpin. Altogether, our data disclose a critical involvement in Cry4Aa-biotoxicity of His180 exclusively present in the lumen-facing α4 for providing proper environment for the α4-α5 hairpin prior to membrane-inserted pore formation.
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Affiliation(s)
- Walairat Bourchookarn
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand
| | - Apichai Bourchookarn
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand.
| | - Chompounoot Imtong
- Faculty of Science and Technology, Prince of Songkla University, Pattani 94000, Thailand
| | - Hui-Chun Li
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan
| | - Chanan Angsuthanasombat
- Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien 97004, Taiwan; Laboratory of Synthetic Biophysics and Chemical Biology, Biophysics Institute for Research and Development (BIRD), Chiang Mai 50230, Thailand; Bacterial Toxin Research Innovation Cluster (BRIC), Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakornpathom 73170, Thailand.
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19
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Pacheco S, Quiliche JPJ, Gómez I, Sánchez J, Soberón M, Bravo A. Rearrangement of N-Terminal α-Helices of Bacillus thuringiensis Cry1Ab Toxin Essential for Oligomer Assembly and Toxicity. Toxins (Basel) 2020; 12:toxins12100647. [PMID: 33049917 PMCID: PMC7601232 DOI: 10.3390/toxins12100647] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/28/2020] [Accepted: 09/28/2020] [Indexed: 12/02/2022] Open
Abstract
Cry proteins produced by Bacillus thuringiensis are pore-forming toxins that disrupt the membrane integrity of insect midgut cells. The structure of such pore is unknown, but it has been shown that domain I is responsible for oligomerization, membrane insertion and pore formation activity. Specifically, it was proposed that some N-terminal α-helices are lost, leading to conformational changes that trigger oligomerization. We designed a series of mutants to further analyze the molecular rearrangements at the N-terminal region of Cry1Ab toxin that lead to oligomer assembly. For this purpose, we introduced Cys residues at specific positions within α-helices of domain I for their specific labeling with extrinsic fluorophores to perform Föster resonance energy transfer analysis to fluorescent labeled Lys residues located in Domains II–III, or for disulfide bridges formation to restrict mobility of conformational changes. Our data support that helix α-1 of domain I is cleaved out and swings away from the toxin core upon binding with Manduca sexta brush border membrane vesicles. That movement of helix α-2b is also required for the conformational changes involved in oligomerization. These observations are consistent with a model proposing that helices α-2b and α-3 form an extended helix α-3 necessary for oligomer assembly of Cry toxins.
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Vílchez S. Making 3D-Cry Toxin Mutants: Much More Than a Tool of Understanding Toxins Mechanism of Action. Toxins (Basel) 2020; 12:toxins12090600. [PMID: 32948025 PMCID: PMC7551160 DOI: 10.3390/toxins12090600] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/15/2020] [Accepted: 08/20/2020] [Indexed: 12/21/2022] Open
Abstract
3D-Cry toxins, produced by the entomopathogenic bacterium Bacillus thuringiensis, have been extensively mutated in order to elucidate their elegant and complex mechanism of action necessary to kill susceptible insects. Together with the study of the resistant insects, 3D-Cry toxin mutants represent one of the pillars to understanding how these toxins exert their activity on their host. The principle is simple, if an amino acid is involved and essential in the mechanism of action, when substituted, the activity of the toxin will be diminished. However, some of the constructed 3D-Cry toxin mutants have shown an enhanced activity against their target insects compared to the parental toxins, suggesting that it is possible to produce novel versions of the natural toxins with an improved performance in the laboratory. In this report, all mutants with an enhanced activity obtained by accident in mutagenesis studies, together with all the variants obtained by rational design or by directed mutagenesis, were compiled. A description of the improved mutants was made considering their historical context and the parallel development of the protein engineering techniques that have been used to obtain them. This report demonstrates that artificial 3D-Cry toxins made in laboratories are a real alternative to natural toxins.
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Affiliation(s)
- Susana Vílchez
- Institute of Biotechnology, Department of Biochemistry and Molecular Biology I, Faculty of Science, University of Granada, 18071 Granada, Spain
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21
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Insecticidal Activity of Bacillus thuringiensis Proteins Against Coleopteran Pests. Toxins (Basel) 2020; 12:toxins12070430. [PMID: 32610662 PMCID: PMC7404982 DOI: 10.3390/toxins12070430] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/25/2020] [Accepted: 06/25/2020] [Indexed: 12/17/2022] Open
Abstract
Bacillus thuringiensis is the most successful microbial insecticide agent and its proteins have been studied for many years due to its toxicity against insects mainly belonging to the orders Lepidoptera, Diptera and Coleoptera, which are pests of agro-forestry and medical-veterinary interest. However, studies on the interactions between this bacterium and the insect species classified in the order Coleoptera are more limited when compared to other insect orders. To date, 45 Cry proteins, 2 Cyt proteins, 11 Vip proteins, and 2 Sip proteins have been reported with activity against coleopteran species. A number of these proteins have been successfully used in some insecticidal formulations and in the construction of transgenic crops to provide protection against main beetle pests. In this review, we provide an update on the activity of Bt toxins against coleopteran insects, as well as specific information about the structure and mode of action of coleopteran Bt proteins.
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Viana JL, Soares-da-Silva J, Vieira-Neta MRA, Tadei WP, Oliveira CD, Abdalla FC, Peixoto CA, Pinheiro VCS. Isolates of Bacillus thuringiensis from Maranhão biomes with potential insecticidal action against Aedes aegypti larvae (Diptera, Culicidae). BRAZ J BIOL 2020; 81:114-124. [PMID: 32130286 DOI: 10.1590/1519-6984.223389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/23/2019] [Indexed: 11/22/2022] Open
Abstract
Entomopathogenic agents are viable and effective options due to their selective action against insects but benign effects on humans and the environment. The most promising entomopathogens include subspecies of Bacillus thuringiensis (Bt), which are widely used for the biological control of insects, including mosquito vectors of human pathogens. The efficacy of B. thuringiensis toxicity has led to the search for new potentially toxic isolates in different regions of the world. Therefore, soil samples from the Amazon, Cerrado and Caatinga biomes of the state of Maranhão were evaluated for their potential larvicidal action against Aedes aegypti. The isolates with high toxicity to mosquito larvae, as detected by bioassays, were subjected to histological evaluation under a light microscope to identify the genes potentially responsible for the toxicity. Additionally, the toxic effects of these isolates on the intestinal epithelium were assessed. In the new B. thuringiensis isolates toxic to A. aegypti larvae, cry and cyt genes were amplified at different frequencies, with cry4, cyt1, cry32, cry10 and cry11 being the most frequent (33-55%) among those investigated. These genes encode specific proteins toxic to dipterans and may explain the severe morphological changes in the intestine of A. aegypti larvae caused by the toxins of the isolates.
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Affiliation(s)
- J L Viana
- Programa de Pós-graduação em Biodiversidade e Biotecnologia da Rede BIONORTE - PPG BIONORTE, Universidade do Estado do Amazonas - UEA, Av. Carvalho Leal, 1777, Ed. Anexo, 4º andar, Cachoeirinha, CEP 69065-00, Manaus, AM, Brasil.,Laboratório de Entomologia Médica, Programa de Pós-graduação em Biodiversidade, Ambiente e Saúde, Centro de Estudos Superiores de Caxias - CESC, Universidade Estadual do Maranhão - UEMA, Praça Duque de Caxias, Morro do Alecrim, s/n, CEP 65604-380, Caxias, MA, Brasil
| | - J Soares-da-Silva
- Coordenação de Ciências Naturais/Biologia, Universidade Federal do Maranhão - UFMA, Campus VII, Av. Dr. José Anselmo, 2008, São Sebastião, CEP 65400-000, Codó, MA, Brasil
| | - M R A Vieira-Neta
- Universidade Federal de São Carlos - UFSCar, Campus Sorocaba, Rodovia João Leme dos Santos, SP-264, Km 110, Itinga, CEP 18052-780, Sorocaba, SP, Brasil
| | - W P Tadei
- Programa de Pós-graduação em Entomologia, Laboratório de Malária e Dengue, Instituto Nacional de Pesquisas da Amazônia - INPA, Av. André Araújo, 2936, Petrópolis, CEP 69067-375, Manaus, AM, Brasil
| | - C D Oliveira
- Grupo Mosquitos Vetores: Endosimbionte e Interação Patógeno Vetor, Centro de Pesquisa René Rachou, Av. Augusto de Lima, 1715, Barro Preto, CEP 30190-002, Belo Horizonte, MG, Brasil
| | - F C Abdalla
- Laboratório de Biologia Estrutural e Funcional - LABEF, Universidade Federal de São Carlos - UFSCar, Campus Sorocaba, Rodovia João Leme dos Santos, SP-264, Itinga, CEP 18052-780, Sorocaba, SP, Brasil
| | - C A Peixoto
- Laboratório de Ultraestrutura, Instituto de Pesquisas Aggeu Magalhães, Fundação Oswaldo Cruz - FIOCRUZ, Av. Moraes Rego, s/n, Campus UFPE, Cidade Universitária, CEP 50740-465, Recife, PE, Brasil
| | - V C S Pinheiro
- Laboratório de Entomologia Médica, Departamento de Química e Biologia, Centro de Estudos Superiores de Caxias - CESC, Universidade Estadual do Maranhão - UEMA, Praça Duque de Caxias, s/n, Morro do Alecrim, CEP 65604-380, Caxias, MA, Brasil
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Hu X, Chen H, Xu J, Zhao G, Huang X, Liu J, Batool K, Wu C, Wu S, Huang E, Wu J, Chowhury M, Zhang J, Guan X, Yu XQ, Zhang L. Function of Aedes aegypti galectin-6 in modulation of Cry11Aa toxicity. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2020; 162:96-104. [PMID: 31836060 DOI: 10.1016/j.pestbp.2019.09.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/09/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
Galectins are a family of β-galactoside binding proteins, and insect galectins play a role in immune responses and may also affect Cry toxin activity. In this study, we aimed to further understand the function and molecular mechanism of Aedes aegypti galectin-6 in modulation of Cry11Aa toxicity. A. aegypti galectin-6 was cloned, and the recombinant galectin-6 was expressed and purified. Bioassays indicated that galectin-6 could reduce the toxicity of Cry11Aa, protecting A. aegypti larvae. To determine interactions among galectin-6, Cry11Aa and putative toxin receptors, Octet Red System, western blotting, far-western blotting and ELISA assays were performed. Octet Red System showed that galectin-6 bound to BBMVs of A. aegypti larvae with lower affinity than that of Cry11Aa. Western blotting and far-western blotting analyses demonstrated that galectin-6 bound to A. aegypti ALP1 and APN2 as well as to BBMVs, consistent with the results of ELISA and protein docking simulations. However, galectin-6 did not bind to Cadherin in far-western blotting or ELISA assay, though the protein docking simulations suggested their binding potential. These findings support the conclusion that galectin-6 may block Cry11Aa from binding to ALP1 and APN2 due to structural similarity, which might decrease the mosquitocidal toxicity of Cry11Aa.
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Affiliation(s)
- Xiaohua Hu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hong Chen
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jin Xu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Guohui Zhao
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xianhui Huang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Jiannan Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Khadija Batool
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Chenxu Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Songqing Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Enjiong Huang
- Fujian International Travel Healthcare Center, Fuzhou 350001, China
| | - Juan Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Munmun Chowhury
- Division of Cell Biology and Biophysics, University of Missouri, Kansas City, MO 64110, USA
| | - Jie Zhang
- Division of Cell Biology and Biophysics, University of Missouri, Kansas City, MO 64110, USA
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiao-Qiang Yu
- Division of Cell Biology and Biophysics, University of Missouri, Kansas City, MO 64110, USA.
| | - Lingling Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops & School of Life Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Division of Cell Biology and Biophysics, University of Missouri, Kansas City, MO 64110, USA.
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Arrata I, Grison CM, Coubrough HM, Prabhakaran P, Little MA, Tomlinson DC, Webb ME, Wilson AJ. Control of conformation in α-helix mimicking aromatic oligoamide foldamers through interactions between adjacent side-chains. Org Biomol Chem 2019; 17:3861-3867. [PMID: 30938392 DOI: 10.1039/c9ob00123a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The design, synthesis and structural characterization of non-natural oligomers that adopt well-defined conformations, so called foldamers, is a key objective in developing biomimetic 3D functional architectures. For the aromatic oligoamide foldamer family, use of interactions between side-chains to control conformation is underexplored. The current manuscript addresses this objective through the design, synthesis and conformational analyses of model dimers derived from 3-O-alkylated para-aminobenzoic acid monomers. The O-alkyl groups on these foldamers are capable of adopting syn- or anti-conformers through rotation around the Ar-CO/NH axes. In the syn-conformation this allows the foldamer to act as a topographical mimic of the α-helix whereby the O-alkyl groups mimic the spatial orientation of the i and i + 4 side-chains from the α-helix. Using molecular modelling and 2D NMR analyses, this work illustrates that covalent links and hydrogen-bonding interactions between side-chains can bias the conformation in favour of the α-helix mimicking syn-conformer, offering insight that may be more widely applied to control secondary structure in foldamers.
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Affiliation(s)
- Irene Arrata
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK.
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25
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BenFarhat-Touzri D, Jemli S, Driss F, Tounsi S. Molecular and structural characterization of a novel Cry1D toxin from Bacillus thuringiensis with high toxicity to Spodoptera littoralis (Lepidoptera: Noctuidae). Int J Biol Macromol 2019; 126:969-976. [PMID: 30593807 DOI: 10.1016/j.ijbiomac.2018.12.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 12/08/2018] [Accepted: 12/19/2018] [Indexed: 10/27/2022]
Abstract
The investigation of new Bacillus thuringiensis (Bt) insecticidal proteins (Cry) with specific toxicity is one of the alternative measures used for Lepidopteran pest control. In the present study, a new Cry toxin was identified from a promising Bt strain BLB250 which was previously selected for its high toxicity against Spodoptera littoralis. The corresponding gene, designated cry1D-250, was cloned. It showed an ORF of 3498bp, encoding a protein of 1165 amino acid residues with a putative molecular mass of 132kDa which was confirmed by SDS-PAGE and Western blot analyses. The corresponding toxin named Cry1D-250 showed a higher insecticidal activity towards S. littoralis than Cry1D-133 (LC50 of 224.4ngcm-2) with an LC50 of only 166ngcm-2. Besides to the 65kDa active toxin, proteolysis activation of Cry1D-133 protein with S. littoralis midgut juice generated an extra form of 56kDa, which was the result of a second cleavage. Via activation study and 3D structure analysis, novel substitutions found in the Cry1D-250 protein compared to Cry1D-133 toxin were shown to be involved in the protein stability and toxicity. Therefore, the Cry1D-250 toxin can be considered to be an effective alternative for the control of S. littoralis.
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Affiliation(s)
- Dalel BenFarhat-Touzri
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box. "1177", 3018 Sfax, Tunisia
| | - Sonia Jemli
- Laboratory of Microbial Biotechnology and Enzyme Engineering, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box. "1177", 3018 Sfax, Tunisia
| | - Fatma Driss
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box. "1177", 3018 Sfax, Tunisia.
| | - Slim Tounsi
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box. "1177", 3018 Sfax, Tunisia
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The C-Terminal Domain of the Bacillus thuringiensis Cry4Ba Mosquito-Specific Toxin Serves as a Potential Membrane Anchor. Toxins (Basel) 2019; 11:toxins11020062. [PMID: 30678087 PMCID: PMC6410236 DOI: 10.3390/toxins11020062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 11/16/2022] Open
Abstract
Although the C-terminal domain (DIII) of three-domain Cry insecticidal toxins from Bacillus thuringiensis has been implicated in various biological functions, its exact role still remains to be elucidated. Here, the 21-kDa isolated DIII fragment of the 65-kDa Cry4Ba mosquito-specific toxin was analyzed for its binding characteristics toward lipid-bilayer membranes. When the highly-purified Cry4Ba-DIII protein was structurally verified by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, it revealed the presence of a distinct β-sheet structure, corresponding to its structure embodied in the Cry4Ba crystal structure. Binding analysis via surface plasmon resonance (SPR) spectroscopy revealed that the 21-kDa Cry4Ba-DIII truncate displayed tight binding to immobilized liposome membranes in a two-step manner, exhibiting a dissociation rate constant (kd) comparable to the 65-kDa full-length toxin. Also similar to the Cry4Ba full-length toxin, its isolated DIII truncate was able to anchor a part of its molecule into the immobilized membrane as the SPR signal was still detected after prolonged treatment with proteinase K. However, unlike the full-length active toxin, the DIII truncate was unable to induce membrane permeability of calcein-loaded liposomes or ion-channel formation in planar lipid bilayers. Together, our present data have disclosed a pivotal role of C-terminal DIII in serving as a membrane anchor rather than a pore-forming moiety of the Cry4Ba mosquito-active toxin, highlighting its potential mechanistic contribution to the interaction of the full-length toxin with lipid membranes in mediating toxicity.
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27
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Zhang LL, Hu XH, Wu SQ, Batool K, Chowdhury M, Lin Y, Zhang J, Gill SS, Guan X, Yu XQ. Aedes aegypti Galectin Competes with Cry11Aa for Binding to ALP1 To Modulate Cry Toxicity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:13435-13443. [PMID: 30556692 DOI: 10.1021/acs.jafc.8b04665] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The key step for the toxicity of Bacillus thuringiensis subsp. israelensis (Bti) is the interaction between toxins and putative receptors; thus, many studies focus on identification of new toxin receptors and engineering of toxins with higher affinity/specificity for receptors. In the larvae of Aedes aegypti, galectin-14 was one of the genes upregulated by Bti treatment. RNAi knockdown expression of galectin-14 and feeding recombinant galectin-14-thioredoxin fusion protein significantly affected survival of Ae. aegypti larvae treated with Bti toxins. Recombinant galectin-14 protein bound to brush border membrane vesicles (BBMVs) of Ae. aegypti larvae, ALP1 and APN2, and galectin-14 and Cry11Aa bound to BBMVs with a similarly high affinity. Competitive binding results showed that galectin-14 competed with Cry11Aa for binding to BBMVs and ALP1 to prevent effective binding of toxin to receptors. These novel findings demonstrated that midgut proteins other than receptors play an important role in modulating the toxicity of Cry toxins.
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Affiliation(s)
- Ling-Ling Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and School of Life Science , Fujian Agriculture and Forestry University , Fuzhou 350002 , China
- Division of Cell Biology and Biophysics , University of Missouri - Kansas City , Kansas City , Missouri 64110 , United States
| | - Xiao-Hua Hu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and School of Life Science , Fujian Agriculture and Forestry University , Fuzhou 350002 , China
| | - Song-Qing Wu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and School of Life Science , Fujian Agriculture and Forestry University , Fuzhou 350002 , China
| | - Khadija Batool
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and School of Life Science , Fujian Agriculture and Forestry University , Fuzhou 350002 , China
| | - Munmun Chowdhury
- Division of Cell Biology and Biophysics , University of Missouri - Kansas City , Kansas City , Missouri 64110 , United States
| | - Yi Lin
- Department of Bioengineering & Biotechnology, College of Chemical Engineering , Huaqiao University , Xiamen 361021 , China
| | - Jie Zhang
- Division of Cell Biology and Biophysics , University of Missouri - Kansas City , Kansas City , Missouri 64110 , United States
| | - Sarjeet S Gill
- Department of Molecular, Cell and Systems Biology , University of California , Riverside , California 92521 , United States
| | - Xiong Guan
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops and School of Life Science , Fujian Agriculture and Forestry University , Fuzhou 350002 , China
| | - Xiao-Qiang Yu
- Division of Cell Biology and Biophysics , University of Missouri - Kansas City , Kansas City , Missouri 64110 , United States
- Guangzhou Key Laboratory of Insect Development Regulation and Application Research, Institute of Insect Science and Technology, and School of Life Sciences , South China Normal University , Guangzhou 510631 , China
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28
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Liu L, Boyd SD, Bulla LA, Winkler DD. "The Defined Toxin-binding Region of the Cadherin G-protein Coupled Receptor, BT-R 1, for the Active Cry1Ab Toxin of Bacillus thuringiensis". ACTA ACUST UNITED AC 2018; 11:201-210. [PMID: 30740004 PMCID: PMC6366636 DOI: 10.4172/0974-276x.1000487] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The bacterium Bacillus thuringiensis (Bt) produces protoxin proteins in parasporal crystals. Proteolysis of the protoxin generates an active toxin which is a potent microbial insecticide. Additionally, Bt toxin genes have been introduced into genetically modified crops to produce insecticidal toxins which protect crops from insect invasion. The insecticidal activity of Cry toxins is mediated by specific interaction between toxins and their respective cellular receptors. One such toxin (Cry1Ab) exerts toxicity by first targeting the 12th ectodomain region (EC12) of the moth cadherin receptor BT-R1. Binding promotes a highly regulated signaling cascade event that concludes in oncotic-like cell death. We previously determined that conserved sequence motifs near the N- and C-termini of EC12 are critical for toxin binding in insect cells. Here, we have established that Cry1Ab specifically binds to EC12 as a soluble heterodimeric complex with extremely high affinity (Kd = 19.5 ± 1.6 nM). Binding assays using Cry1Ab toxin and a fluorescently labeled EC12 revealed that the heterodimeric complex is highly specific in that no such formation occurs between EC12 and other Cry toxins active against beetle and mosquito. Disruption of one or both terminal sequence motifs in EC12 eliminates complex formation. Until now, comprehensive biophysical characterization of Cry1Ab recognition and binding by the BT-R1 receptor was unresolved. The findings presented here provide insight on the molecular determinants in the Cry family of toxins and should facilitate the assessment and advancement of their use as pesticidal agents.
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Affiliation(s)
- Li Liu
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75083, USA
| | - Stefanie D Boyd
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75083, USA
| | - Lee A Bulla
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75083, USA.,CustomGene, LLC, Tioga, TX 76271, USA
| | - Duane D Winkler
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75083, USA
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29
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Jing X, Yuan Y, Wu Y, Wu D, Gong P, Gao M. Crystal structure of Bacillus thuringiensis Cry7Ca1 toxin active against Locusta migratoria manilensis. Protein Sci 2018; 28:609-619. [PMID: 30506755 DOI: 10.1002/pro.3561] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/25/2018] [Accepted: 11/23/2018] [Indexed: 01/06/2023]
Abstract
Insecticidal crystal (Cry) proteins produced by Bacillus thuringiensis (Bt) are widely used as environmentally friendly insecticides. As the only known Cry protein with insecticidal activity against Locusta migratoria manilensis, a locust subspecies that causes extensive destruction of crops, the Cry7Ca1 protein from Bt strain BTH-13 identified in our previous study is of particular interest to locust prevention and control. However, the three-dimensional structure of Cry7Ca1 toxin (the active form of the Cry7Ca1 protein) and the mechanisms of the Cry7Ca1 insecticidal specificity remain largely elusive. Here, we report a 2.3 Å crystal structure of the Cry7Ca1 toxin and carry out a systematic comparison of all available Cry toxins structures. A cluster of six loops in Cry toxin domain II, named Apex here, are the most variable structural elements and were documented to contribute in insecticidal specificity. The Cry7Ca1 toxin Apex loops are different from those of other Cry toxins in length, conformation, and sequence. Electrostatic potential analysis further revealed that Cry7Ca1 is the only structure-available Cry toxin that does not have a high contrast of surface electrostatic potentials in the Apex. We further suggest that the L1/L2 loops in the center of the Cry7Ca1 Apex may be worthy of attention in future efforts to unravel the Cry7Ca1 insecticidal specificity as they exhibit unique features not found in the corresponding regions of other Cry toxins. Our work highlights the uniqueness of the Apex in the Cry7Ca1 toxin and may assist exploration of the insecticidal mechanism of the Cry7Ca1 against Locusta migratoria manilensis.
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Affiliation(s)
- Xuping Jing
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yihui Yuan
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
| | - Yan Wu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
| | - Dandan Wu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
| | - Peng Gong
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
| | - Meiying Gao
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China
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Cheng C, Qin J, Wu C, Lei M, Wang Y, Zhang L. Suppressing a plant-parasitic nematode with fungivorous behavior by fungal transformation of a Bt cry gene. Microb Cell Fact 2018; 17:116. [PMID: 30037328 PMCID: PMC6055344 DOI: 10.1186/s12934-018-0960-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Accepted: 07/09/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Pine wilt disease, caused by the pinewood nematode Bursaphelenchus xylophilus (PWN), is an important destructive disease of pine forests worldwide. In addition to behaving as a plant-parasitic nematode that feeds on epithelial cells of pines, this pest relies on fungal associates for completing its life cycle inside pine trees. Manipulating microbial symbionts to block pest transmission has exhibited an exciting prospect in recent years; however, transforming the fungal mutualists to toxin delivery agents for suppressing PWN growth has received little attention. RESULTS In the present study, a nematicidal gene cry5Ba3, originally from a soil Bacillus thuringiensis (Bt) strain, was codon-preferred as cry5Ba3Φ and integrated into the genome of a fungus eaten by PWN, Botrytis cinerea, using Agrobacterium tumefaciens-mediated transformation. Supplementing wild-type B. cinerea extract with that from the cry5Ba3Φ transformant significantly suppressed PWN growth; moreover, the nematodes lost fitness significantly when feeding on the mycelia of the cry5Ba3Φ transformant. N-terminal deletion of Cry5Ba3Φ protein weakened the nematicidal activity more dramatically than did the C-terminal deletion, indicating that domain I (endotoxin-N) plays a more important role in its nematicidal function than domain III (endotoxin-C), which is similar to certain insecticidal Cry proteins. CONCLUSIONS Transformation of Bt nematicidal cry genes in fungi can alter the fungivorous performance of B. xylophilus and reduce nematode fitness. This finding provides a new prospect of developing strategies for breaking the life cycle of this pest in pines and controlling pine wilt disease.
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Affiliation(s)
- Chihang Cheng
- Collaborative Innovation Center of Zhejiang Green Pesticide, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China
- School of Life Sciences, Huzhou University, Huzhou, 313000, China
| | - Jialing Qin
- Collaborative Innovation Center of Zhejiang Green Pesticide, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China
| | - Choufei Wu
- Collaborative Innovation Center of Zhejiang Green Pesticide, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China
- School of Life Sciences, Huzhou University, Huzhou, 313000, China
| | - Mengying Lei
- Guangdong Eco-Engineering Polytechnic, Guangdong, 510520, China
| | - Yongjun Wang
- Collaborative Innovation Center of Zhejiang Green Pesticide, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China.
- State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China.
| | - Liqin Zhang
- Collaborative Innovation Center of Zhejiang Green Pesticide, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China.
- School of Life Sciences, Huzhou University, Huzhou, 313000, China.
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Helix α-3 inter-molecular salt bridges and conformational changes are essential for toxicity of Bacillus thuringiensis 3D-Cry toxin family. Sci Rep 2018; 8:10331. [PMID: 29985464 PMCID: PMC6037675 DOI: 10.1038/s41598-018-28753-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/29/2018] [Indexed: 12/31/2022] Open
Abstract
Bacillus thuringiensis insecticidal Cry toxins break down larval midgut-cells after forming pores. The 3D-structures of Cry4Ba and Cry5Ba revealed a trimeric-oligomer after cleavage of helices α-1 and α-2a, where helix α-3 is extended and made contacts with adjacent monomers. Molecular dynamic simulations of Cry1Ab-oligomer model based on Cry4Ba-coordinates showed that E101 forms a salt-bridge with R99 from neighbor monomer. An additional salt bridge was identified in the trimeric-Cry5Ba, located at the extended helix α-3 in the region corresponding to the α-2b and α-3 loop. Both salt-bridges were analyzed by site directed mutagenesis. Single-point mutations in the Lepidoptera-specific Cry1Ab and Cry1Fa toxins were affected in toxicity, while reversed double-point mutant partially recovered the phenotype, consistent with a critical role of these salt-bridges. The single-point mutations in the salt-bridge at the extended helix α-3 of the nematicidal Cry5Ba were also non-toxic. The incorporation of this additional salt bridge into the nontoxic Cry1Ab-R99E mutant partially restored oligomerization and toxicity, supporting that the loop between α-2b and α-3 forms part of an extended helix α-3 upon oligomerization of Cry1 toxins. Overall, these results highlight the role in toxicity of salt-bridge formation between helices α-3 of adjacent monomers supporting a conformational change in helix α-3.
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Sellami S, Jemli S, Abdelmalek N, Cherif M, Abdelkefi-Mesrati L, Tounsi S, Jamoussi K. A novel Vip3Aa16-Cry1Ac chimera toxin: Enhancement of toxicity against Ephestia kuehniella, structural study and molecular docking. Int J Biol Macromol 2018; 117:752-761. [PMID: 29800666 DOI: 10.1016/j.ijbiomac.2018.05.161] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/14/2018] [Accepted: 05/22/2018] [Indexed: 10/16/2022]
Abstract
Bacillus thuringiensis Vip3A protein has been widely used for crop protection and for delay resistance to existing insecticidal Cry toxins. During current study, a fusion between vip3Aa16 and the toxic core sequence of cry1Ac was constructed in pHT Blue plasmid. Vip3Aa16-Cry1Ac protein was expressed in the supernatant of B. thuringiensis with a size of about 150 kDa. Bioassays tested on Ephestia kuehniella showed that the use of the chimera toxin as biopesticide improved the toxicity to reach 90% ± 2 with an enhancement of 20% compared to the single Vip3Aa16 protein. The findings indicated that the fusion protein design opens new ways to enhance Vip3A toxicity against lepidopteran species and could avoiding insect tolerance of B. thuringiensis delta-endotoxins. Through computational study, we have predicted for the first time the whole 3D structure of a Vip3A toxin. We showed that Vip3Aa16 structure is composed by three domains like Cry toxins: an N-terminal domain containing hemolysin like fold as well as two others Carbohydrate Binding Module (CBM)-like domains. Molecular docking analysis of the chimera toxin and the single Vip3Aa16 protein against specific insect receptors revealed that residues of CBM like domains are clearly involved in the binding of the toxin to receptors.
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Affiliation(s)
- Sameh Sellami
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia.
| | - Sonia Jemli
- Laboratory of Microbial Biotechnology and Enzymes Engineering, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Nouha Abdelmalek
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Marwa Cherif
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Lobna Abdelkefi-Mesrati
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Slim Tounsi
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
| | - Kais Jamoussi
- Laboratory of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
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Liu M, Huang R, Weisman A, Yu X, Lee SH, Chen Y, Huang C, Hu S, Chen X, Tan W, Liu F, Chen H, Shea KJ. Synthetic Polymer Affinity Ligand for Bacillus thuringiensis (Bt) Cry1Ab/Ac Protein: The Use of Biomimicry Based on the Bt Protein–Insect Receptor Binding Mechanism. J Am Chem Soc 2018; 140:6853-6864. [DOI: 10.1021/jacs.8b01710] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Mingming Liu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
- Department of Chemistry, University of California−Irvine, Irvine, California 92697, United States
| | - Rong Huang
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Adam Weisman
- Department of Chemistry, University of California−Irvine, Irvine, California 92697, United States
| | - Xiaoyang Yu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Shih-Hui Lee
- Department of Chemistry, University of California−Irvine, Irvine, California 92697, United States
| | - Yalu Chen
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Chao Huang
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Senhua Hu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiuhua Chen
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Wenfeng Tan
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Fan Liu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Hao Chen
- College of Science, Huazhong Agricultural University, Wuhan 430070, China
| | - Kenneth J. Shea
- Department of Chemistry, University of California−Irvine, Irvine, California 92697, United States
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Xu L, Pan ZZ, Zhang J, Niu LY, Li J, Chen Z, Liu B, Zhu YJ, Chen QX. Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure. Cell Microbiol 2018; 20:e12827. [PMID: 29380507 DOI: 10.1111/cmi.12827] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 01/15/2018] [Accepted: 01/17/2018] [Indexed: 12/15/2022]
Abstract
Cry2Ab, a pore-forming toxin derived from Bacillus thuringiensis, is widely used as a bio-insecticide to control lepidopteran pests around the world. A previous study revealed that proteolytic activation of Cry2Ab by Plutella xylostella midgut juice was essential for its insecticidal activity against P. xylostella, although the exact molecular mechanism remained unknown. Here, we demonstrated for the first time that proteolysis of Cry2Ab uncovered an active region (the helices α4 and α5 in Domain I), which was required for the mode of action of Cry2Ab. Either the masking or the removal of helices α4 and α5 mediated the pesticidal activity of Cry2Ab. The exposure of helices α4 and α5 did not facilitate the binding of Cry2Ab to P. xylostella midgut receptors but did induce Cry2Ab monomer to aggregate and assemble a 250-kDa prepore oligomer. Site-directed mutagenesis assay was performed to generate Cry2Ab mutants site directed on the helices α4 and α5, and bioassays suggested that some Cry2Ab variants that could not form oligomers had significantly lowered their toxicities against P. xylostella. Taken together, our data highlight the importance of helices α4 and α5 in the mode of action of Cry2Ab and could lead to more detailed studies on the insecticidal activity of Cry2Ab.
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Affiliation(s)
- Lian Xu
- State Key Laboratory of Cellular Stress Biology, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Zhi-Zhen Pan
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, People's Republic of China
| | - Jing Zhang
- State Key Laboratory of Cellular Stress Biology, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Li-Yang Niu
- State Key Laboratory of Cellular Stress Biology, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Jie Li
- State Key Laboratory of Cellular Stress Biology, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
| | - Zheng Chen
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, People's Republic of China
| | - Bo Liu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, People's Republic of China
| | - Yu-Jing Zhu
- Agricultural Bio-Resources Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou, Fujian, People's Republic of China
| | - Qing-Xi Chen
- State Key Laboratory of Cellular Stress Biology, Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen, Fujian, People's Republic of China
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Soberón M, Monnerat R, Bravo A. Mode of Action of Cry Toxins from Bacillus thuringiensis and Resistance Mechanisms. TOXINOLOGY 2018. [DOI: 10.1007/978-94-007-6449-1_28] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Zhang Q, Hua G, Adang MJ. Effects and mechanisms of Bacillus thuringiensis crystal toxins for mosquito larvae. INSECT SCIENCE 2017; 24:714-729. [PMID: 27628909 DOI: 10.1111/1744-7917.12401] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 08/15/2016] [Accepted: 08/22/2016] [Indexed: 06/06/2023]
Abstract
Bacillus thuringiensis is a Gram-positive aerobic bacterium that produces insecticidal crystalline inclusions during sporulation phases of the mother cell. The virulence factor, known as parasporal crystals, is composed of Cry and Cyt toxins. Most Cry toxins display a common 3-domain topology. Cry toxins exert intoxication through toxin activation, receptor binding and pore formation in a suitable larval gut environment. The mosquitocidal toxins of Bt subsp. israelensis (Bti) were found to be highly active against mosquito larvae and are widely used for vector control. Bt subsp. jegathesan is another strain which possesses high potency against broad range of mosquito larvae. The present review summarizes characterized receptors for Cry toxins in mosquito larvae, and will also discuss the diversity and effects of 3-D mosquitocidal Cry toxin and the ongoing research for Cry toxin mechanisms generated from investigations of lepidopteran and dipteran larvae.
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Affiliation(s)
- Qi Zhang
- College of Plant Protection, Shenyang Agricultural University, Shenyang, China
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Gang Hua
- Department of Entomology, University of Georgia, Athens, GA, USA
| | - Michael J Adang
- Department of Entomology, University of Georgia, Athens, GA, USA
- Department of Biochemistry & Molecular Biology, University of Georgia, Athens, GA, USA
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An Intramolecular Salt Bridge in Bacillus thuringiensis Cry4Ba Toxin Is Involved in the Stability of Helix α-3, Which Is Needed for Oligomerization and Insecticidal Activity. Appl Environ Microbiol 2017; 83:AEM.01515-17. [PMID: 28802270 DOI: 10.1128/aem.01515-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 08/04/2017] [Indexed: 01/30/2023] Open
Abstract
Bacillus thuringiensis three-domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intramolecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity. These mutants were also altered in oligomerization, and the mutant K115D was more sensitive to protease digestion. The double point mutant with reversed charges, D111K-K115D, recovered both oligomerization and toxicity, suggesting that this salt bridge is highly important for conservation of the structure of helix α-3 and necessary to promote the correct oligomerization of the toxin.IMPORTANCE Domain I has been shown to be involved in oligomerization through helix α-3 in different Cry toxins, and mutations affecting oligomerization also elicit changes in toxicity. The three-dimensional structure of the Cry4Ba toxin reveals an intramolecular salt bridge in helix α-3 of domain I. Mutations that disrupt this salt bridge resulted in changes in Cry4Ba oligomerization and toxicity, while a double point reciprocal mutation that restored the salt bridge resulted in recovery of toxin oligomerization and toxicity. These data highlight the role of oligomer formation as a key step in Cry4Ba toxicity.
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Hayakawa T, Sakakibara A, Ueda S, Azuma Y, Ide T, Takebe S. Cry46Ab from Bacillus thuringiensis TK-E6 is a new mosquitocidal toxin with aerolysin-type architecture. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2017; 87:100-106. [PMID: 28676354 DOI: 10.1016/j.ibmb.2017.06.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/30/2017] [Accepted: 06/30/2017] [Indexed: 06/07/2023]
Abstract
Cry46Ab is a Cry toxin derived from Bacillus thuringiensis TK-E6. Cry46Ab is not significantly homologous to other mosquitocidal Cry or Cyt toxins and is classified as an aerolysin-type pore-forming toxin based on structural similarity. In this study, the potency of Cry46Ab was assessed for its potential application to mosquito control. A synthetic Cry46Ab gene, cry46Ab-S1, was designed to produce recombinant Cry46Ab as a glutathione-S-transferase fusion in Escherichia coli. Recombinant Cry46Ab showed apparent toxicity to Culex pipiens larvae, with a 50% lethal dose of 1.02 μg/ml. In an artificial lipid bilayer, Cry46Ab activated by trypsin caused typical current transitions between open and closed states, suggesting it functions as a pore-forming toxin similar to other Cry and Cyt toxins. The single-channel conductance was 103.3 ± 4.1 pS in 150 mM KCl. Co-administration of recombinant Cry46Ab with other mosquitocidal Cry toxins, especially the combination of Cry4Aa and Cry46Ab, resulted in significant synergistic toxicity against C. pipiens larvae. Co-administration of multiple toxins exhibiting different modes of action is believed to prevent the onset of resistance in insects. Our data, taken in consideration with the differences in its structure, suggest that Cry46Ab could be useful in not only reducing resistance levels but also improving the insecticidal activity of Bt-based bio-insecticides.
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Affiliation(s)
- Tohru Hayakawa
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
| | - Akira Sakakibara
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Sho Ueda
- Graduate School of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Kinokawa 649-6493, Japan
| | - Yoshinao Azuma
- Graduate School of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Kinokawa 649-6493, Japan
| | - Toru Ide
- Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - So Takebe
- Graduate School of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Kinokawa 649-6493, Japan
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Fortea E, Lemieux V, Potvin L, Chikwana V, Griffin S, Hey T, McCaskill D, Narva K, Tan SY, Xu X, Vachon V, Schwartz JL. Cry6Aa1, a Bacillus thuringiensis nematocidal and insecticidal toxin, forms pores in planar lipid bilayers at extremely low concentrations and without the need of proteolytic processing. J Biol Chem 2017. [PMID: 28623231 DOI: 10.1074/jbc.m116.765941] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cry6Aa1 is a Bacillus thuringiensis (Bt) toxin active against nematodes and corn rootworm insects. Its 3D molecular structure, which has been recently elucidated, is unique among those known for other Bt toxins. Typical three-domain Bt toxins permeabilize receptor-free planar lipid bilayers (PLBs) by forming pores at doses in the 1-50 μg/ml range. Solubilization and proteolytic activation are necessary steps for PLB permeabilization. In contrast to other Bt toxins, Cry6Aa1 formed pores in receptor-free bilayers at doses as low as 200 pg/ml in a wide range of pH (5.5-9.5) and without the need of protease treatment. When Cry6Aa1 was preincubated with Western corn rootworm (WCRW) midgut juice or trypsin, 100 fg/ml of the toxin was sufficient to form pores in PLBs. The overall biophysical properties of the pores were similar for all three forms of the toxin (native, midgut juice- and trypsin-treated), with conductances ranging from 28 to 689 pS, except for their ionic selectivity, which was slightly cationic for the native and midgut juice-treated Cry6Aa1, whereas dual selectivity (to cations or anions) was observed for the pores formed by the trypsin-treated toxin. Enrichment of PLBs with WCRW midgut brush-border membrane material resulted in a 2000-fold reduction of the amount of native Cry6Aa1 required to form pores and affected the biophysical properties of both the native and trypsin-treated forms of the toxin. These results indicate that, although Cry6Aa1 forms pores, the molecular determinants of its mode of action are significantly different from those reported for other Bt toxins.
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Affiliation(s)
- Eva Fortea
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Vincent Lemieux
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada.,the Département de biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Léna Potvin
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | | | | | - Timothy Hey
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | | | - Kenneth Narva
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Sek Yee Tan
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Xiaoping Xu
- Dow AgroSciences LLC, Indianapolis, Indiana 46268, and
| | - Vincent Vachon
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Jean-Louis Schwartz
- From the Département de pharmacologie et physiologie and Groupe d'étude des protéines membranaires, Université de Montréal, Montreal, Québec H3C 3J7, Canada, .,the Centre SÈVE de recherche en sciences du végétal, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1 Canada
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Biological Control Strategies for Mosquito Vectors of Arboviruses. INSECTS 2017; 8:insects8010021. [PMID: 28208639 PMCID: PMC5371949 DOI: 10.3390/insects8010021] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/21/2017] [Indexed: 12/16/2022]
Abstract
Historically, biological control utilizes predatory species and pathogenic microorganisms to reduce the population of mosquitoes as disease vectors. This is particularly important for the control of mosquito-borne arboviruses, which normally do not have specific antiviral therapies available. Although development of resistance is likely, the advantages of biological control are that the resources used are typically biodegradable and ecologically friendly. Over the past decade, the advancement of molecular biology has enabled optimization by the manipulation of genetic materials associated with biological control agents. Two significant advancements are the discovery of cytoplasmic incompatibility induced by Wolbachia bacteria, which has enhanced replacement programs, and the introduction of dominant lethal genes into local mosquito populations through the release of genetically modified mosquitoes. As various arboviruses continue to be significant public health threats, biological control strategies have evolved to be more diverse and become critical tools to reduce the disease burden of arboviruses.
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Insecticidal Specificity of Cry1Ah to Helicoverpa armigera Is Determined by Binding of APN1 via Domain II Loops 2 and 3. Appl Environ Microbiol 2017; 83:AEM.02864-16. [PMID: 27940541 DOI: 10.1128/aem.02864-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 12/01/2016] [Indexed: 12/20/2022] Open
Abstract
Bacillus thuringiensis Cry1Ah protein is highly toxic against Helicoverpa armigera but shows no toxicity against Bombyx mori larvae. In contrast, the closely related Cry1Ai toxin showed the opposite phenotype: high activity against B. mori but no toxicity against H. armigera. Analysis of binding of Cry1Ah to brush border membrane vesicle (BBMV) proteins from H. armigera and B. mori by surface plasmon resonance revealed association of toxin binding with insect specificity. Pulldown experiments identified aminopeptidase N1 (APN1) as a Cry1Ah binding protein that was not observed in the assays using B. mori BBMV proteins. The APN1 Cry1Ah binding region was narrowed to the region from A548 to S798 (fragment H3) by expressing four different APN1 fragments in Escherichia coli and analyzing Cry1Ah binding by ligand blot. Binding competition experiments of Cry1Ah to APN1 fragment H3 using synthetic peptides corresponding to four predicted domain II loop regions showed that loop 2 and loop 3 have additive effects on binding to APN1 fragment H3. Moreover, switching of loop 2 and loop 3 regions from Cry1Ah to Cry1Ai toxins showed that loop 2 and loop 3 are both involved in specificity and toxicity against H. armigera IMPORTANCE: Domain II loop regions have been shown to be involved in binding to larval gut proteins mediating insect specificity. The modification of loop regions is a direct and effective method to construct new Cry toxin variants to increase toxicity or modify specificity. Our results show that the exchange of loop regions from one toxin into another is a successful scheme for modification of B. thuringiensis Cry toxin specificity.
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El-kersh TA, Ahmed AM, Al-sheikh YA, Tripet F, Ibrahim MS, Metwalli AAM. Isolation and characterization of native Bacillus thuringiensis strains from Saudi Arabia with enhanced larvicidal toxicity against the mosquito vector Anopheles gambiae (s.l.). Parasit Vectors 2016; 9:647. [PMID: 27993165 PMCID: PMC5168711 DOI: 10.1186/s13071-016-1922-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 11/30/2016] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Worldwide, mosquito vectors are transmitting several etiological agents of important human diseases, including malaria, causing millions of deaths every year. In Saudi Arabia, as elsewhere, vector-control is based mostly on chemical insecticides which may be toxic and cause environmental deprivation. Here, to support the development of bio-pesticide alternatives, a study was conducted to identify native Bacillus thuringiensis (Bt) isolates with improved toxicity against the malaria vector, Anopheles gambiae (s.l.). METHODS Sixty-eight Bt isolates were obtained from 300 soil and other samples collected from 16 sites across Saudi Arabia. Bt identification was based on morphological characteristics of colonies, shape of parasporal crystals and biochemical profiles. After characterization of their mosquitocidal activity, larvicidal strains were described through 16S ribosomal DNA gene sequencing, cry, cyt and chi genes PCR-amplification profiles, and SDS-PAGE protein analyses. RESULTS Spherical Bt crystals were predominant amongst the 68 isolates (34%), while irregular, bi-pyramidal and spore-attached crystals were found in 32, 13 and 21% of strains, respectively. LC50 and LC90 bioassays showed that 23/68 isolates were larvicidal, with distinct biochemical activity profiles compared to non-larvicidal Bt strains. Eight larvicidal strains showed larvicidal activity up to 3.4-fold higher (LC50 range: 3.90-7.40 μg/ml) than the reference Bti-H14 strain (LC50 = 13.33 μg/ml). Of these, 6 strains had cry and cyt gene profiles similar to Bti-H14 (cry4Aa, cry4Ba, cry10, cry11, cyt1Aa, cyt1Ab, cyt2Aa). The seventh strain (Bt63) displaying the highest larvicidal activity (LC50 = 3.90 μg/ml) missed the cry4Aa and cyt1Ab genes and had SDS-PAGE protein profiles and spore/crystal sizes distinct from Bti-H14. The eight strain (Bt55) with LC50 of 4.11μg/ml had cry and cyt gene profiles similar to Bti-H14 but gave a chi gene PCR product size of 2027bp. No strains harbouring cry2, cry17 + 27, cry24 + 40, cry25, cry29, cry30, or cyt2Ba were detected. CONCLUSION This study represents the first report of several Saudi indigenous Bt strains with significantly higher larvicidal efficacy against An. gambiae than the reference Bti-H14 strain. The very high toxicity of the Bt63 strain, combined with distinct cry and cyt genes and SDS-PAGE-protein profiles makes it a promising candidate for future applications in mosquito bio-control.
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Affiliation(s)
- Talaat A. El-kersh
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ashraf M. Ahmed
- Department of Zoology, College of Science, King Saud University, Riyadh, Saudi Arabia
| | - Yazeed A. Al-sheikh
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Frédéric Tripet
- Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire, ST5 5BG UK
| | - Mohamed S. Ibrahim
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
| | - Ali A. M. Metwalli
- Department of Food Science & Nutrition, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia
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Buzatto D, de Castro França S, Zingaretti SM. CryGetter: a tool to automate retrieval and analysis of Cry protein data. BMC Bioinformatics 2016; 17:325. [PMID: 27578522 PMCID: PMC5004295 DOI: 10.1186/s12859-016-1207-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 08/24/2016] [Indexed: 11/30/2022] Open
Abstract
Background For many years, the use of chemical agents to control crop pests has been degrading the environment, bringing problems to humans and all living things. An alternative to deal with the pests is the use of biopesticides, biological agents capable of controlling these harmful organisms. One kind of biopesticide is Bacillus thuringiensis, a Gram-positive bacterium that synthesizes a protein that, when ingested by the pests, kills them and does not harm other species. Results Since the economical importance of Bacillus thuringiensis and its proteins significance, this work presents a software tool, called CryGetter, that is capable of retrieving data related to these proteins, store it and present it in a user friendly manner. The tool also aims to align the protein sequences and generate reports containing some statistical data concerning the alignments that were made. Conclusions CryGetter was created to help researchers of Bacillus thuringiensis and its proteins to speed up their data retrieval and analysis, allowing them to generate more accurate results. In this sense, the tool circumvents the error prone task of manually getting all the necessary data and processing them in various software systems to get the same result as CryGetter gets in a unique semiautomatic environment.
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Affiliation(s)
- David Buzatto
- Instituto Federal de Educação, Ciência e Tecnologia de São Paulo - IFSP, Câmpus São João da Boa Vista, Acesso Dr. João Batista Merlin, s/n, Jardim Itália, São João da Boa Vista, 13872-551, SP, Brazil.
| | - Suzelei de Castro França
- Universidade de Ribeirão Preto - UNAERP, Av. Costábile Romano, 2201, Ribeirânia, Ribeirão Preto, 14096-000, SP, Brazil
| | - Sônia Marli Zingaretti
- Universidade de Ribeirão Preto - UNAERP, Av. Costábile Romano, 2201, Ribeirânia, Ribeirão Preto, 14096-000, SP, Brazil
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Guo QY, Hu XM, Cai QX, Yan JP, Yuan ZM. Interaction of Lysinibacillus sphaericus Cry48Aa/Cry49Aa toxin with midgut brush-border membrane fractions from Culex quinquefasciatus larvae. INSECT MOLECULAR BIOLOGY 2016; 25:163-170. [PMID: 26748768 DOI: 10.1111/imb.12209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Cry48Aa/Cry49Aa mosquitocidal toxin from Lysinibacillus sphaericus was uniquely composed of a three-domain (Cry) toxin and binary (Bin) toxin-like protein, with high toxicity against Culex spp. However, its mode of action against the target mosquitoes is still unknown. In this study, Cry48Aa, Cry49Aa and its N- and C-terminal truncated proteins were expressed and purified, and the binding affinities of the purified proteins with midgut brush-border membrane fractions (BBMFs) from Culex quin-quefasciatus larvae were performed. The results showed that both Cry48Aa and Cry49Aa have specific and high binding affinity to BBMFs, with dissociation constants of 9.5 ± 1.8 and 25.4 ± 3.8 nM, respectively. Competition assays demonstrated that Cry49Aa C-terminal derivatives were able to bind to the BBMFs, whereas Far-Western dot blot analysis revealed that its N-terminal constructs interacted with Cry48Aa. Nevertheless, larvicidal activity was almost lost when Cry49Aa truncated proteins, either individually or in pairs, combined with Cry48Aa. It is concluded that Cry49Aa is responsible for receptor binding and interaction with Cry48Aa and plays an important role in the mechanism of action of these two-component toxins.
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Affiliation(s)
- Q-Y Guo
- College of Life and Environmental Sciences, Gannan Normal University, Ganzhou, China
| | - X-M Hu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Q-X Cai
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - J-P Yan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Z-M Yuan
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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Kaikaew A, Promptmas C, Angsuthanasombat C. Importance of Thr328 and Thr369 for functional maintenance of two receptor-binding β-hairpins of the Bacillus thuringiensis Cry4Ba toxin: Implications for synergistic interactions with Cyt2Aa2. Biochem Biophys Res Commun 2016; 469:698-703. [DOI: 10.1016/j.bbrc.2015.11.115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
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Rubio-Infante N, Moreno-Fierros L. An overview of the safety and biological effects of Bacillus thuringiensis Cry toxins in mammals. J Appl Toxicol 2015; 36:630-48. [PMID: 26537666 DOI: 10.1002/jat.3252] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 09/08/2015] [Accepted: 09/09/2015] [Indexed: 12/12/2022]
Abstract
Crystal proteins (Cry) produced during the growth and sporulation phases of Bacillus thuringiensis (Bt) bacterium are known as delta endotoxins. These toxins are being used worldwide as bioinsecticides to control pests in agriculture, and some Cry toxins are used against mosquitoes to control vector transmission. This review summarizes the relevant information currently available regarding the biosafety and biological effects that Bt and its insecticidal Cry proteins elicit in mammals. This work was performed because of concerns regarding the possible health impact of Cry toxins on vertebrates, particularly because Bt toxins might be associated with immune-activating or allergic responses. The controversial data published to date are discussed in this review considering earlier toxicological studies of B. thuringiensis, spores, toxins and Bt crops. We discussed the experimental studies performed in humans, mice, rats and sheep as well as in diverse mammalian cell lines. Although the term 'toxic' is not appropriate for defining the effects these toxins have on mammals, they cannot be considered innocuous, as they have some physiological effects that may become pathological; thus, trials that are more comprehensive are necessary to determine their effects on mammals because knowledge in this field remains limited.
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Affiliation(s)
- Néstor Rubio-Infante
- Laboratorio de Inmunidad en Mucosas, Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes Iztacala, Tlalnepantla, 54090, Estado de México, México
| | - Leticia Moreno-Fierros
- Laboratorio de Inmunidad en Mucosas, Unidad de Biomedicina, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios 1, Los Reyes Iztacala, Tlalnepantla, 54090, Estado de México, México
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Lacey L, Grzywacz D, Shapiro-Ilan D, Frutos R, Brownbridge M, Goettel M. Insect pathogens as biological control agents: Back to the future. J Invertebr Pathol 2015. [DOI: 10.1016/j.jip.2015.07.009] [Citation(s) in RCA: 545] [Impact Index Per Article: 60.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Elleuch J, Jaoua S, Darriet F, Chandre F, Tounsi S, Zghal RZ. Cry4Ba and Cyt1Aa proteins from Bacillus thuringiensis israelensis: Interactions and toxicity mechanism against Aedes aegypti. Toxicon 2015; 104:83-90. [DOI: 10.1016/j.toxicon.2015.07.337] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/24/2015] [Accepted: 07/30/2015] [Indexed: 11/28/2022]
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Evidence of two mechanisms involved in Bacillus thuringiensis israelensis decreased toxicity against mosquito larvae: Genome dynamic and toxins stability. Microbiol Res 2015; 176:48-54. [DOI: 10.1016/j.micres.2015.04.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/07/2015] [Accepted: 04/17/2015] [Indexed: 11/23/2022]
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Leetachewa S, Moonsom S, Chaisri U, Khomkhum N, Yoonim N, Wang P, Angsuthanasombat C. Functional characterizations of residues Arg-158 and Tyr-170 of the mosquito-larvicidal Bacillus thuringiensis Cry4Ba. BMB Rep 2015; 47:546-51. [PMID: 24286331 PMCID: PMC4261511 DOI: 10.5483/bmbrep.2014.47.10.192] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Indexed: 11/26/2022] Open
Abstract
The insecticidal activity of Bacillus thuringiensis (Bt) Cry toxins involves toxin stabilization, oligomerization, passage across the peritrophic membrane (PM), binding to midgut receptors and pore-formation. The residues Arg-158 and Tyr-170 have been shown to be crucial for the toxicity of Bt Cry4Ba. We characterized the biological function of these residues. In mosquito larvae, the mutants R158A/E/Q (R158) could hardly penetrate the PM due to a significantly reduced ability to alter PM permeability; the mutant Y170A, however, could pass through the PM, but degraded in the space between the PM and the midgut epithelium. Further characterization by oligomerization demonstrated that Arg-158 mutants failed to form correctly sized high-molecular weight oligomers. This is the first report that Arg-158 plays a role in the formation of Cry4Ba oligomers, which are essential for toxin passage across the PM. Tyr-170, meanwhile, is involved in toxin stabilization in the toxic mechanism of Cry4Ba in mosquito larvae. [BMB Reports 2014; 47(10): 546-551]
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Affiliation(s)
- Somphob Leetachewa
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Nakhon-Pathom 73170, Thailand
| | - Saengduen Moonsom
- Department of Protozoology, Faculty of Tropical Medicine, Mahidol University, Ratchathewi, Bangkok 10400, Thailand
| | - Urai Chaisri
- Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Ratchathewi, Bangkok 10400, Thailand
| | - Narumol Khomkhum
- Department of Protozoology, Faculty of Tropical Medicine, Mahidol University, Ratchathewi, Bangkok 10400, Thailand
| | - Nonglak Yoonim
- Faculty of Medical Technology, Western University, Kanchanaburi 71170, Thailand
| | - Ping Wang
- Department of Entomology, New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, USA
| | - Chanan Angsuthanasombat
- Bacterial Protein Toxin Research Cluster, Institute of Molecular Biosciences, Mahidol University, Nakhon-Pathom 73170, Thailand
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