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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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Guo Q, Ding L, Gao Y, Niu Y, Dai X. Cys183 and Cys258 in Cry49Aa toxin from Lysinibacillus sphaericus are essential for toxicity to Culex quinquefasciatus larvae. Arch Microbiol 2021; 203:4587-4592. [PMID: 34160628 DOI: 10.1007/s00203-021-02436-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
The two-component Cry48Aa/Cry49Aa toxin produced by Lysinibacillus sphaericus shows specifically toxic to Culex quinquefasciatus mosquito larvae. Cry49Aa C-terminal domain is responsible for specific binding to the larval gut cell membrane, while its N-terminal domain is required for interaction with Cry48Aa. To investigate functional role of cysteine in Cry49Aa, four cysteine residues at positions 70, 91, 183, and 258 were substituted by alanine. All mutants showed similar crystalline morphology and comparable yield to that of the wild type except that the yield of the C91A mutant was low. Four cysteine residues did not involve in disulfide bond formation within or between Cry49Aa molecules. Cys91, Cys183, and Cys258 are essential for larvicidal activity against C. quinquefasciatus larvae, while Cys70 is not. Substitution at C91, C183, and C258 caused weaker Cry48Aa- Cry49Aa interaction, while mutations at C183 and C258 reduced the binding capacities to the larval gut cell membrane. Thus, Cysteine residues at position 91, 183, and 258 in Cry49Aa are required for full toxicity of Cry48Aa/Cry49Aa toxin.
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Affiliation(s)
- Qingyun Guo
- College of Life Sciences, Gannan Normal University, Shida South Road 1, Ganzhou City, Jiangxi Province, 341000, People's Republic of China.
| | - Lu Ding
- College of Life Sciences, Gannan Normal University, Shida South Road 1, Ganzhou City, Jiangxi Province, 341000, People's Republic of China
| | - Yuan Gao
- College of Life Sciences, Gannan Normal University, Shida South Road 1, Ganzhou City, Jiangxi Province, 341000, People's Republic of China
| | - Yingchao Niu
- College of Life Sciences, Gannan Normal University, Shida South Road 1, Ganzhou City, Jiangxi Province, 341000, People's Republic of China
| | - Xiaohua Dai
- College of Life Sciences, Gannan Normal University, Shida South Road 1, Ganzhou City, Jiangxi Province, 341000, People's Republic of China
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Tharad S, Tangsongcharoen C, Boonserm P, L. Toca-Herrera J, Srisucharitpanit K. Local conformations affect the histidine tag-Ni 2+ binding affinity of BinA and BinB proteins. AIMS BIOPHYSICS 2020. [DOI: 10.3934/biophy.2020011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Kelker MS, Berry C, Evans SL, Pai R, McCaskill DG, Wang NX, Russell JC, Baker MD, Yang C, Pflugrath JW, Wade M, Wess TJ, Narva KE. Structural and biophysical characterization of Bacillus thuringiensis insecticidal proteins Cry34Ab1 and Cry35Ab1. PLoS One 2014; 9:e112555. [PMID: 25390338 PMCID: PMC4229197 DOI: 10.1371/journal.pone.0112555] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/07/2014] [Indexed: 11/18/2022] Open
Abstract
Bacillus thuringiensis strains are well known for the production of insecticidal proteins upon sporulation and these proteins are deposited in parasporal crystalline inclusions. The majority of these insect-specific toxins exhibit three domains in the mature toxin sequence. However, other Cry toxins are structurally and evolutionarily unrelated to this three-domain family and little is known of their three dimensional structures, limiting our understanding of their mechanisms of action and our ability to engineer the proteins to enhance their function. Among the non-three domain Cry toxins, the Cry34Ab1 and Cry35Ab1 proteins from B. thuringiensis strain PS149B1 are required to act together to produce toxicity to the western corn rootworm (WCR) Diabrotica virgifera virgifera Le Conte via a pore forming mechanism of action. Cry34Ab1 is a protein of ∼14 kDa with features of the aegerolysin family (Pfam06355) of proteins that have known membrane disrupting activity, while Cry35Ab1 is a ∼44 kDa member of the toxin_10 family (Pfam05431) that includes other insecticidal proteins such as the binary toxin BinA/BinB. The Cry34Ab1/Cry35Ab1 proteins represent an important seed trait technology having been developed as insect resistance traits in commercialized corn hybrids for control of WCR. The structures of Cry34Ab1 and Cry35Ab1 have been elucidated to 2.15 Å and 1.80 Å resolution, respectively. The solution structures of the toxins were further studied by small angle X-ray scattering and native electrospray ion mobility mass spectrometry. We present here the first published structure from the aegerolysin protein domain family and the structural comparisons of Cry34Ab1 and Cry35Ab1 with other pore forming toxins.
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Affiliation(s)
- Matthew S. Kelker
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
| | - Colin Berry
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Steven L. Evans
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
| | - Reetal Pai
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
| | | | - Nick X. Wang
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
| | - Joshua C. Russell
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
| | - Matthew D. Baker
- Cardiff School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Cheng Yang
- Rigaku Americas Corporation, The Woodlands, Texas, United States of America
| | - J. W. Pflugrath
- Rigaku Americas Corporation, The Woodlands, Texas, United States of America
| | - Matthew Wade
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Tim J. Wess
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom
| | - Kenneth E. Narva
- Dow AgroSciences, LLC, Indianapolis, Indiana, United States of America
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Kale A, Hire RS, Hadapad AB, D'Souza SF, Kumar V. Interaction between mosquito-larvicidal Lysinibacillus sphaericus binary toxin components: analysis of complex formation. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1045-1054. [PMID: 23974012 DOI: 10.1016/j.ibmb.2013.07.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 07/19/2013] [Accepted: 07/29/2013] [Indexed: 06/02/2023]
Abstract
The two components (BinA and BinB) of Lysinibacillus sphaericus binary toxin together are highly toxic to Culex and Anopheles mosquito larvae, and have been employed world-wide to control mosquito borne diseases. Upon binding to the membrane receptor an oligomeric form (BinA2.BinB2) of the binary toxin is expected to play role in pore formation. It is not clear if these two proteins interact in solution as well, in the absence of receptor. The interactions between active forms of BinA and BinB polypeptides were probed in solution using size-exclusion chromatography, pull-down assay, surface plasmon resonance, circular dichroism, and by chemically crosslinking BinA and BinB components. We demonstrate that the two proteins interact weakly with first association and dissociation rate constants of 4.5×10(3) M(-1) s(-1) and 0.8 s(-1), resulting in conformational change, most likely, in toxic BinA protein that could kinetically favor membrane translocation of the active oligomer. The weak interactions between the two toxin components could be stabilized by glutaraldehyde crosslinking. The cross-linked complex, interestingly, showed maximal Culex larvicidal activity (LC50 value of 1.59 ng mL(-1)) reported so far for combination of BinA/BinB components, and thus is an attractive option for development of new bio-pesticides for control of mosquito borne vector diseases.
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Affiliation(s)
- Avinash Kale
- High Pressure & Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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Srisucharitpanit K, Inchana P, Rungrod A, Promdonkoy B, Boonserm P. Expression and purification of the active soluble form of Bacillus sphaericus binary toxin for structural analysis. Protein Expr Purif 2012; 82:368-72. [PMID: 22381463 DOI: 10.1016/j.pep.2012.02.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 02/08/2012] [Accepted: 02/10/2012] [Indexed: 10/28/2022]
Abstract
The binary toxin produced from Bacillus sphaericus is highly toxic against larvae of Culex and Anopheles mosquitoes. The two major components of the binary toxin are 42-kDa BinA and 51-kDa BinB, which are produced as crystalline inclusions during sporulation. Currently, there is no detailed knowledge of the molecular mechanism of the binary toxin, mainly due to the lack of structural information. Herein, we describe an expression protocol with modified conditions allowing production of soluble, biologically active BinA and BinB for further structural analysis. The binA and binB genes from B. sphaericus 2297 strain were independently cloned and fused with a polyhistidine tag at their N-termini. Both (His)(6)-tagged BinA and (His)(6)-tagged BinB were expressed as soluble forms at low temperature. Highly pure proteins were obtained after two-step purification by Ni-NTA affinity and size exclusion chromatography. In vitro activation by trypsin digestion generated a resistant fragment, of 40kDa for BinA, and of 45kDa for BinB, and an oligomeric complex of BinA and BinB in solution was observed after proteolytic activation. Their functional and structural properties were confirmed by a biological assay and far-UV circular dichroism, respectively. The mixture of BinA and BinB, either as a protoxin or as a trypsin-activated form, exhibited high mosquito-larvicidal activity against Culex quinquefasciatus larvae with LC(50) of about 10ng/ml, while no toxicity was observed from the single binary toxin component. Results from far-UV circular dichroism of BinA and BinB suggest the presence of mainly β-structure. The expression and purification protocols reported here will be useful for the production of the active and homogeneous binary toxin to allow further detailed structural investigation.
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Affiliation(s)
- Kanokporn Srisucharitpanit
- Institute of Molecular Biosciences, Mahidol University, Salaya, Phuttamonthon, Nakhon Pathom 73170, Thailand
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da Silva Pinto L, Gonçales RA, Conceição FR, Knabah PF, Borsuk S, Campos VF, Arruda FV, Leite FPL. Stability, oviposition attraction, and larvicidal activity of binary toxin from Bacillus sphaericus expressed in Escherichia coli. Appl Microbiol Biotechnol 2011; 95:1235-41. [PMID: 22202967 DOI: 10.1007/s00253-011-3808-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/28/2011] [Accepted: 12/01/2011] [Indexed: 11/30/2022]
Abstract
Bacillus sphaericus produces a two-chain binary toxin composed of BinA (42 kDa) and BinB (51 kDa), which are deposited as parasporal crystals during sporulation. The toxin is highly active against Culex larvae and Aedes and Anopheles mosquitoes, which are the principal vectors for the transmission of malaria, yellow fever, encephalitis, and dengue. The use of B. sphaericus and Bacillus thuringiensis in mosquito control programs is limited by their sedimentation in still water. In this study, the binA and binB genes were cloned and the recombinant BinAB protein was expressed in three strains of Escherichia coli. These recombinant strains were used in a toxicity assay against Culex quinquefasciatus larvae. The highest expression level was achieved when both proteins were expressed in a single operon construct. The BinAB protein expressed in the E. coli Arctic strain showed higher larvicidal activity than either of the recombinant proteins from the E. coli Ril or pLysS strains. Furthermore, it had the highest oviposition attraction (49.1%, P < 0.05). These data suggest that biologically active recombinant BinA and BinB toxins might be useful in mosquito control programs, delivered by inactivated bacterial cells or in traps.
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Affiliation(s)
- Luciano da Silva Pinto
- Centro de Desenvolvimento Tecnológico, Núcleo Biotecnologia, UFPel, Campus Universitário, s/n, Caixa Postal 354, Pelotas, RS, 96010-900, Brazil.
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Berry C. The bacterium, Lysinibacillus sphaericus, as an insect pathogen. J Invertebr Pathol 2011; 109:1-10. [PMID: 22137877 DOI: 10.1016/j.jip.2011.11.008] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 10/12/2011] [Indexed: 10/15/2022]
Abstract
Since the first bacteria with insecticidal activity against mosquito larvae were reported in the 1960s, many have been described, with the most potent being isolates of Bacillus thuringiensis or Lysinibacillus sphaericus (formerly and best known as Bacillus sphaericus). Given environmental concerns over the use of broad spectrum synthetic chemical insecticides and the evolution of resistance to these, industry placed emphasis on the development of bacteria as alternative control agents. To date, numerous commercial formulations of B. thuringiensis subsp. israelensis (Bti) are available in many countries for control of nuisance and vector mosquitoes. Within the past few years, commercial formulations of L. sphaericus (Ls) have become available. Because Bti has been in use for more than 30 years, its properties are well know, more so than those of Ls. Thus, the purpose of this review is to summarise the most critical aspects of Ls and the various proteins that account for its insecticidal properties, especially the mosquitocidal activity of the most common isolates studied. Data are reviewed for the binary toxin, which accounts for the activity of sporulated cells, as well as for other toxins produced during vegetative growth, including sphaericolysin (active against cockroaches and caterpillars) and the different mosquitocidal Mtx and Cry toxins. Future studies of these could well lead to novel potent and environmentally compatible insecticidal products for controlling a range of insect pests and vectors of disease.
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Affiliation(s)
- Colin Berry
- Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
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Romão TP, de-Melo-Neto OP, Silva-Filha MHNL. The N-terminal third of the BinB subunit from the Bacillus sphaericus binary toxin is sufficient for its interaction with midgut receptors in Culex quinquefasciatus. FEMS Microbiol Lett 2011; 321:167-74. [DOI: 10.1111/j.1574-6968.2011.02325.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Park HW, Bideshi DK, Federici BA. Properties and applied use of the mosquitocidal bacterium, Bacillus sphaericus. JOURNAL OF ASIA-PACIFIC ENTOMOLOGY 2010; 13:159-168. [PMID: 28883761 PMCID: PMC5584542 DOI: 10.1016/j.aspen.2010.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Strains of Bacillus sphaericus exhibit varying levels of virulence against mosquito larvae. The most potent strain, B. sphaericus 2362, which is the active ingredient in the commercial product VectoLex®, together with another well-known larvicide Bacillus thuringiensis subsp. israelensis, are used to control vector and nuisance mosquito larvae in many regions of the world. Although not all strains of B. sphaericus are mosquitocidal, lethal strains produce one or two combinations of three different types of toxins. These are (1) the binary toxin (Bin) composed of two proteins of 42 kDa (BinA) and 51 kDa (BinB), which are synthesized during sporulation and co-crystallize, (2) the soluble mosquitocidal toxins (Mtx1, Mtx2 and Mtx3) produced during vegetative growth, and (3) the two-component crystal toxin (Cry48Aa1/Cry49Aa1). Non-mosquitocidal toxins are also produced by certain strains of B. sphaericus, for examples sphaericolysin, a novel insecticidal protein toxic to cockroaches. Larvicides based on B. sphaericus-based have the advantage of longer persistence in treated habitats compared to B. thuringiensis subsp. israelensis. However, resistance is a much greater threat, and has already emerged at significant levels in field populations in China and Thailand treated with B. sphaericus. This likely occurred because toxicity depends principally on Bin rather than various combinations of crystal (Cry) and cytolytic (Cyt) toxins present in B. thuringiensis subsp. israelensis. Here we review both the general characteristics of B. sphaericus, particularly as they relate to larvicidal isolates, and strategies or considerations for engineering more potent strains of this bacterium that contain built-in mechanisms that delay or overcome resistance to Bin in natural mosquito populations.
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Affiliation(s)
- Hyun-Woo Park
- Department of Natural and Mathematical Sciences, California Baptist University, Riverside, CA 92504, USA
| | - Dennis K. Bideshi
- Department of Natural and Mathematical Sciences, California Baptist University, Riverside, CA 92504, USA
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA
| | - Brian A. Federici
- Department of Entomology, University of California, Riverside, Riverside, CA 92521, USA
- Interdepartmental graduate programs in Genetics, Genomics and Bioinformatics and Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, CA 92521, USA
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Singkhamanan K, Promdonkoy B, Chaisri U, Boonserm P. Identification of amino acids required for receptor binding and toxicity of theBacillus sphaericusâbinary toxin. FEMS Microbiol Lett 2010; 303:84-91. [DOI: 10.1111/j.1574-6968.2009.01865.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Boonyos P, Soonsanga S, Boonserm P, Promdonkoy B. Role of cysteine at positions 67, 161 and 241 of a Bacillus sphaericus binary toxin BinB. BMB Rep 2010; 43:23-8. [DOI: 10.5483/bmbrep.2010.43.1.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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