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Kinkar OU, Prashar A, Yadav B, Kumar A, Hadapad AB, Hire RS, Makde RD. Purification, characterization and proteolytic processing of mosquito larvicidal protein Cry11Aa from Bacillus thuringensis subsp. isralensis ISPC-12. Int J Biol Macromol 2023:124979. [PMID: 37245748 DOI: 10.1016/j.ijbiomac.2023.124979] [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: 02/23/2023] [Revised: 05/17/2023] [Accepted: 05/18/2023] [Indexed: 05/30/2023]
Abstract
Cry11Aa is the most potent mosquito larvicidal protein of Bacillus thuringiensis subsp. israelensis (Bti). Development of resistance against insecticidal proteins including Cry11Aa is known but no field resistance was observed with Bti. The phenomenon of increasing resistance in insect pests necessitates the development of new strategies and techniques to enhance efficacy of insecticidal proteins. Recombinant technology offers better control over the molecule and allows modification of protein to achieve maximal effect against target pests. In this study, we standardised protocol for recombinant purification of Cry11Aa. Recombinant Cry11Aa found active against larvae of Aedes and Culex mosquito species and LC50 were estimated. Detailed biophysical characterization provides crucial insights into stability and in-vitro behaviour of the recombinant Cry11Aa. Moreover, trypsin hydrolysis doesn't improve overall toxicity of recombinant Cry11Aa. Proteolytic processing suggests domain I and II are more prone to proteolysis in comparison to domain III. Significance of structural features for proteolysis of Cry11Aa was observed after performing molecular dynamics simulations. Findings reported here are contributing significantly in method for purification, understanding in-vitro behaviour and proteolytic processing of Cry11Aa which could facilitate in efficient utilisation of Bti for insect pests and vectors control.
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Affiliation(s)
- 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
| | - Arpit Prashar
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India.
| | - Beena Yadav
- 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.
| | - Ramesh S Hire
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, Maharashtra, India; 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.
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Barbieri G, Ferrari C, Mamberti S, Gabrieli P, Castelli M, Sassera D, Ursino E, Scoffone VC, Radaelli G, Clementi E, Sacchi L, Ferrari E, Gasperi G, Albertini AM. Identification of a Novel Brevibacillus laterosporus Strain With Insecticidal Activity Against Aedes albopictus Larvae. Front Microbiol 2021; 12:624014. [PMID: 33679643 PMCID: PMC7925996 DOI: 10.3389/fmicb.2021.624014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/19/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial species able to produce proteins that are toxic against insects have been discovered at the beginning of the last century. However, up to date only two of them have been used as pesticides in mosquito control strategies targeting larval breeding sites: Bacillus thuringensis var. israelensis and Lysinibacillus sphaericus. Aiming to expand the arsenal of biopesticides, bacterial cultures from 44 soil samples were assayed for their ability to kill larvae of Aedes albopictus. A method to select, grow and test the larvicidal capability of spore-forming bacteria from each soil sample was developed. This allowed identifying 13 soil samples containing strains capable of killing Ae. albopictus larvae. Among the active isolates, one strain with high toxicity was identified as Brevibacillus laterosporus by 16S rRNA gene sequencing and by morphological characterization using transmission electron microscopy. The new isolate showed a larvicidal activity significantly higher than the B. laterosporus LMG 15441 reference strain. Its genome was phylogenomically characterized and compared to the available Brevibacillus genomes. Thus, the new isolate can be considered as a candidate adjuvant to biopesticides formulations that would help preventing the insurgence of resistance.
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Affiliation(s)
- Giulia Barbieri
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Carolina Ferrari
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Stefania Mamberti
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Paolo Gabrieli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy.,Department of Biosciences, University of Milan, Milan, Italy
| | - Michele Castelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Davide Sassera
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Emanuela Ursino
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Viola Camilla Scoffone
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Giacomo Radaelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Emanuela Clementi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Luciano Sacchi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Eugenio Ferrari
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Giuliano Gasperi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Alessandra M Albertini
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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Potential for Bacillus thuringiensis and Other Bacterial Toxins as Biological Control Agents to Combat Dipteran Pests of Medical and Agronomic Importance. Toxins (Basel) 2020; 12:toxins12120773. [PMID: 33291447 PMCID: PMC7762171 DOI: 10.3390/toxins12120773] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 11/24/2020] [Accepted: 12/03/2020] [Indexed: 11/16/2022] Open
Abstract
The control of dipteran pests is highly relevant to humans due to their involvement in the transmission of serious diseases including malaria, dengue fever, Chikungunya, yellow fever, zika, and filariasis; as well as their agronomic impact on numerous crops. Many bacteria are able to produce proteins that are active against insect species. These bacteria include Bacillus thuringiensis, the most widely-studied pesticidal bacterium, which synthesizes proteins that accumulate in crystals with insecticidal properties and which has been widely used in the biological control of insects from different orders, including Lepidoptera, Coleoptera, and Diptera. In this review, we summarize all the bacterial proteins, from B. thuringiensis and other entomopathogenic bacteria, which have described insecticidal activity against dipteran pests, including species of medical and agronomic importance.
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Bacillus thuringiensis subsp. israelensis and its dipteran-specific toxins. Toxins (Basel) 2014; 6:1222-43. [PMID: 24686769 PMCID: PMC4014730 DOI: 10.3390/toxins6041222] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/10/2014] [Accepted: 03/14/2014] [Indexed: 01/05/2023] Open
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) is the first Bacillus thuringiensis to be found and used as an effective biological control agent against larvae of many mosquito and black fly species around the world. Its larvicidal activity resides in four major (of 134, 128, 72 and 27 kDa) and at least two minor (of 78 and 29 kDa) polypeptides encoded respectively by cry4Aa, cry4Ba, cry11Aa, cyt1Aa, cry10Aa and cyt2Ba, all mapped on the 128 kb plasmid known as pBtoxis. These six δ-endotoxins form a complex parasporal crystalline body with remarkably high, specific and different toxicities to Aedes, Culex and Anopheles larvae. Cry toxins are composed of three domains (perforating domain I and receptor binding II and III) and create cation-selective channels, whereas Cyts are composed of one domain that acts as well as a detergent-like membrane perforator. Despite the low toxicities of Cyt1Aa and Cyt2Ba alone against exposed larvae, they are highly synergistic with the Cry toxins and hence their combinations prevent emergence of resistance in the targets. The lack of significant levels of resistance in field mosquito populations treated for decades with Bti-bioinsecticide suggests that this bacterium will be an effective biocontrol agent for years to come.
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Otieno-Ayayo ZN, Zaritsky A, Wirth MC, Manasherob R, Khasdan V, Cahan R, Ben-Dov E. Variations in the mosquito larvicidal activities of toxins from Bacillus thuringiensis ssp. israelensis. Environ Microbiol 2008; 10:2191-9. [PMID: 18637949 DOI: 10.1111/j.1462-2920.2008.01696.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Comparing activities of purified toxins from Bacillus thuringiensis ssp. israelensis against larvae of seven mosquito species (vectors of tropical diseases) that belong to three genera, gleaned from the literature, disclosed highly significant variations in the levels of LC(50) as well as in the hierarchy of susceptibilities. Similar toxicity comparisons were performed between nine transgenic Gram-negative species, four of which are cyanobacterial, expressing various combinations of cry genes, cyt1Aa and p20, against larvae of four mosquito species as potential agents for biological control. Reasons for inconsistencies are listed and discussed. Standard conditions for toxin isolation and presentation to larvae are sought. A set of lyophilized powders prepared identically from six Escherichia coli clones expressing combinations of four genes displayed toxicities against larvae of three mosquito species, with levels that differed between them but with identical hierarchy.
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Oestergaard J, Ehlers RU, Martínez-Ramírez AC, Real MD. Binding of Cyt1Aa and Cry11Aa toxins of Bacillus thuringiensis serovar israelensis to brush border membrane vesicles of Tipula paludosa (Diptera: Nematocera) and subsequent pore formation. Appl Environ Microbiol 2007; 73:3623-9. [PMID: 17416690 PMCID: PMC1932698 DOI: 10.1128/aem.01056-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus thuringiensis serovar israelensis (B. thuringiensis subsp. israelensis) produces four insecticidal crystal proteins (ICPs) (Cry4A, Cry4B, Cry11A, and Cyt1A). Toxicity of recombinant B. thuringiensis subsp. israelensis strains expressing only one of the toxins was determined with first instars of Tipula paludosa (Diptera: Nematocera). Cyt1A was the most toxic protein, whereas Cry4A, Cry4B, and Cry11A were virtually nontoxic. Synergistic effects were recorded when Cry4A and/or Cry4B was combined with Cyt1A but not with Cry11A. The binding and pore formation are key steps in the mode of action of B. thuringiensis subsp. israelensis ICPs. Binding and pore-forming activity of Cry11Aa, which is the most toxic protein against mosquitoes, and Cyt1Aa to brush border membrane vesicles (BBMVs) of T. paludosa were analyzed. Solubilization of Cry11Aa resulted in two fragments, with apparent molecular masses of 32 and 36 kDa. No binding of the 36-kDa fragment to T. paludosa BBMVs was detected, whereas the 32-kDa fragment bound to T. paludosa BBMVs. Only a partial reduction of binding of this fragment was observed in competition experiments, indicating a low specificity of the binding. In contrast to results for mosquitoes, the Cyt1Aa protein bound specifically to the BBMVs of T. paludosa, suggesting an insecticidal mechanism based on a receptor-mediated action, as described for Cry proteins. Cry11Aa and Cyt1Aa toxins were both able to produce pores in T. paludosa BBMVs. Protease treatment with trypsin and proteinase K, previously reported to activate Cry11Aa and Cyt1Aa toxins, respectively, had the opposite effect. A higher efficiency in pore formation was observed when Cyt1A was proteinase K treated, while the activity of trypsin-treated Cry11Aa was reduced. Results on binding and pore formation are consistent with results on ICP toxicity and synergistic effect with Cyt1Aa in T. paludosa.
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Affiliation(s)
- Jesko Oestergaard
- Institute for Phytopathology, Department of Biotechnology and Biological Control, Christian Albrechts University, Hermann-Rodewald Str. 9, 24118 Kiel, Germany
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Yamagiwa M, Ogawa R, Yasuda K, Natsuyama H, Sen K, Sakai H. Active form of dipteran-specific insecticidal protein cryllA produced by Bacillus thuringiensis subsp. israelensis. Biosci Biotechnol Biochem 2002; 66:516-22. [PMID: 12005043 DOI: 10.1271/bbb.66.516] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The nucleotide sequence of the cry11A gene from Bacillus thuringiensis subsp. israelensis strain HD522 was analyzed and the molecular characterization of CryllA toxin was done. The 70-kDa CryllA protoxin was processed in vitro into 36- and 32-kDa fragments by trypsin and into 34- and 32-kDa fragments by gut proteases from C. pipiens. These two processed fragments are associated together to form the heterodimer. The results of the binding assay with BBMV and the bioassay toward C. pipiens larvae suggested that the heterodimer was biologically as active as the non-digested CryllA toxin and the intramolecular cleavage did not promote the insecticidal activity. These results suggested that a probable complex of the 36- or 34-kDa and 32-kDa fragments was also one of the possible active forms of Cry11A, and that the biological functions of CryllA was not essentially affected by the intramolecular cleavage of the 70-kDa protein.
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Affiliation(s)
- Masashi Yamagiwa
- Department of Bioscience and Biotechnology, Okayama University, Japan
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Regis L, Silva-Filha MH, Nielsen-LeRoux C, Charles JF. Bacteriological larvicides of dipteran disease vectors. Trends Parasitol 2001; 17:377-80. [PMID: 11685898 DOI: 10.1016/s1471-4922(01)01953-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The apparent success in vector control observed between 1950 and 1970 was followed by worldwide resistance to organosynthetic insecticides wherever they were used intensively. Insect resistance to one or more categories of insecticides has limited the effectiveness of these compounds, and their non-selective mode of action adversely affects non-target organisms. This scenario highlights the need for selective agents in integrated vector control programs. This article gives an overview of the main fundamental and applied research topics on entomopathogenic bacteria in relation to their role in vector control.
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Affiliation(s)
- L Regis
- Fundação Oswaldo Cruz-Fiocruz, CPqAM, Dept Entomology, Av Moraes Rego s/n 50670.420 Recife, PE, Brazil.
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Gutierrez P, Alzate O, Orduz S. A theoretical model of the tridimensional structure of Bacillus thuringiensis subsp. medellin Cry 11Bb toxin deduced by homology modelling. Mem Inst Oswaldo Cruz 2001; 96:357-64. [PMID: 11313644 DOI: 10.1590/s0074-02762001000300013] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cry11Bb is an insecticidal crystal protein produced by Bacillus thuringiensis subsp. medellin during its stationary phase; this partial differential-endotoxin is active against dipteran insects and has great potential for mosquito borne disease control. Here, we report the first theoretical model of the tridimensional structure of a Cry11 toxin. The tridimensional structure of the Cry11Bb toxin was obtained by homology modelling on the structures of the Cry1Aa and Cry3Aa toxins. In this work we give a brief description of our model and hypothesize the residues of the Cry11Bb toxin that could be important in receptor recognition and pore formation. This model will serve as a starting point for the design of mutagenesis experiments aimed to the improvement of toxicity, and to provide a new tool for the elucidation of the mechanism of action of these mosquitocidal proteins.
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Affiliation(s)
- P Gutierrez
- Unidad de Biotecnología y Control Biológico, Corporación para Investigaciones Biológica, Medellin, Colombia
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Okumura S, Akao T, Mizuki E, Ohba M, Inouye K. Screening of the Bacillus thuringiensis Cry1Ac delta-endotoxin on the artificial phospholipid monolayer incorporated with brush border membrane vesicles of Plutella xylostella by optical biosensor technology. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2001; 47:177-88. [PMID: 11245889 DOI: 10.1016/s0165-022x(00)00134-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The binding of Cry1Ac, an insecticidal protein of Bacillus thuringiensis, to a brush border membrane (BBM) isolated from midguts of the diamondback moth Plutella xylostella was examined by surface plasmon resonance (SPR)-based biosensor. BBM was mixed with 1,3-ditetradecylglycero-2-phosphocholine (PC14), a neutral charged artificial lipid, and was reconstructed to a monolayer on a hydrophobic chip for the biosensor. The binding of Cry1Ac to the reconstructed monolayer was analyzed by a two-state binding model, and it was shown that Cry1Ac bound to the monolayer in the first step with an affinity constant (K(1)) of 508 nM, followed by the second uni-molecular step with an equilibrium constant (K(2)) of 0.472. The overall affinity constant K(d) was determined to be 240 nM. The binding was markedly inhibited by N-acetyl-D-galactosamine (K(i)=8 mM). The monolayer was shown to retain a high affinity to Cry1Ac, providing an insect-free system for rapid and large-scale screening of B. thuringiensis insecticidal proteins by the SPR-based biosensor technology.
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Affiliation(s)
- S Okumura
- Fukuoka Industrial Technology Center, 1465-5 Aikawa, Kurume, 839-0861, Fukuoka, Japan
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Abdul-Rauf M, Ellar DJ. Isolation and characterization of brush border membrane vesicles from whole Aedes aegypti larvae. J Invertebr Pathol 1999; 73:45-51. [PMID: 9878289 DOI: 10.1006/jipa.1998.4792] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Studies of the binding interactions of dipteran-specific Bacillus thuringiensis delta-endotoxins are hindered by the lengthy midgut dissection procedure needed for preparation of brush border membrane vesicles. In an attempt to resolve this problem, brush border membrane vesicles were isolated from homogenates of whole Aedes aegypti larvae by a modification of the method of MacIntosh et al. (1994). These preparations were found to resolve well on SDS-PAGE and appeared as spherical vesicles of various sizes under electron microscopic examination. Specific activities of the brush border membrane marker enzymes alkaline phosphatase and leucine amino acid arylamidase were enriched 10.9- and 10.7-fold, respectively. Direct binding experiments using 35S-labeled B. thuringiensis CryIC toxin revealed a single class of high-affinity binding sites with a dissociation constant (Kd) of 27 +/- 0.6 nM and a maximum binding capacity (Bmax) of approximately 27 +/- 1.2 pmol/mg BBMV protein. These binding parameters are similar to those of vesicles prepared from isolated midguts, indicating that whole larval brush border membrane vesicles are suitable for in vitro membrane binding studies.
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Affiliation(s)
- M Abdul-Rauf
- Institute of Cancer Research/Royal Marsden Hospital, Haddow Laboratories, Sutton, Surrey, SM2 5NG
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Denolf P, Hendrickx K, Van Damme J, Jansens S, Peferoen M, Degheele D, Van Rie J. Cloning and characterization of Manduca sexta and Plutella xylostella midgut aminopeptidase N enzymes related to Bacillus thuringiensis toxin-binding proteins. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 248:748-61. [PMID: 9342226 DOI: 10.1111/j.1432-1033.1997.t01-1-00748.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We report the purification, cloning and characterization of an aminopeptidase N from the midgut epithelium of Manduca sexta that binds Cry1Ab5, an insecticidal crystal protein [ICP] from Bacillus thuringiensis. Sequence information derived from this M. sexta aminopeptidase N was used for the cloning of an aminopeptidase N from the midgut brush-border membrane of Plutella xylostella, an insect species of which some populations acquired resistance against Cry1Ab5. Affinity chromatography on a Cry1Ab5 matrix was used to isolate a 120-kDa glycoprotein from the larval midgut of the lepidopteran M. sexta. On ligand blots the purified 120-kDa protein discriminates between the lepidopteran-specific Cry1Ab5 and the coleopteran-specific Cry3A delta-endotoxin. Internal amino acid sequences from the 120-kDa protein were used for the design of degenerate oligonucleotides. From a nested PCR with M. sexta midgut cDNA as template, a DNA fragment was obtained which shows similarity to prokaryotic and eukaryotic aminopeptidase N genes. This PCR fragment was used to screen cDNA libraries of larval midguts from M. sexta and P. xylostella. From the M. sexta midgut cDNA library a 2973-bp nucleotide sequence was cloned. The ORF of the sequence encodes a 942-residue aminopeptidase N (M. sexta Apn2) containing two hydrophobic regions. The NH2-terminal hydrophobic region corresponds to a secretory signal sequence and the COOH-terminal hydrophobic region is typical of glycosylphosphatidylinositol (glycosyl-PtdIns)-anchored proteins. Low-stringency hybridization of the P. xylostella midgut cDNA library with M. sexta apn2 probes enabled the isolation of a 3118-bp sequence with an ORF encoding a 946-residue preproprotein. This aminopeptidase N (P. xylostella Apn1) displays 61% amino acid identity to M. sexta Apn2 and contains a COOH-terminal signal peptide for glycosyl-PtdIns anchor addition. Both M. sexta Apn2 and P. xylostella Apn1 contain four Cys residues, which are highly conserved among eukaryotic aminopeptidase N molecules. Treatment of Sf9 cells expressing the P. xylostella apn1 gene with PtdIns-specific phospholipase C demonstrated that P. xylostella Apn1 is attached to the insect cell membrane by a glycosyl-PtdIns anchor.
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Affiliation(s)
- P Denolf
- Plant Genetic Systems, Gent, Belgium.
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Silva-Filha MH, Nielsen-Leroux C, Charles JF. Binding kinetics of Bacillus sphaericus binary toxin to midgut brush-border membranes of Anopheles and Culex sp. mosquito larvae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 247:754-61. [PMID: 9288894 DOI: 10.1111/j.1432-1033.1997.00754.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Direct-binding assays and homologous-competition assays were used to identify specific binding between the radiolabelled toxin of Bacillus sphaericus and brush-border membrane fractions (BBMF) from Anopheles gambiae and Anopheles stephensi, obtained from whole larvae preparations. In both species, the toxin bound to a single class of receptors. BBMF of A. gambiae had the highest binding affinity for the toxin of the species tested, with a dissociation constant (Kd) of 30 +/- 15 nM and a maximum receptor concentration of 5 +/- 1 pmol/mg. Toxin binding to A. gambiae BBMF was compared with that to BBMF from B. sphaericus-susceptible (IP) and B. sphaericus-resistant (SPHAE) Culex pipiens populations. BBMF toxin binding was slower in A. gambiae than in the C. pipiens populations. The BBMF of the B. sphaericus-resistant population of C. pipiens had an association profile that was similar to the susceptible population, despite of the lack of susceptibility in vivo. No relationship between toxicity and irreversibility of toxin binding was detected. On the contrary, toxin dissociation from BBMF was fast and almost complete in BBMF of all species studied.
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Du C, Nickerson KW. The Bacillus thuringiensis insecticidal toxin binds biotin-containing proteins. Appl Environ Microbiol 1996; 62:2932-9. [PMID: 8702286 PMCID: PMC168080 DOI: 10.1128/aem.62.8.2932-2939.1996] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Brush border membrane vesicles from larvae of the tobacco hornworm, Manduca sexta, contain protein bands of 85 and 120 kDa which react directly with streptavidin conjugated to alkaline phosphatase. The binding could be prevented either by including 10 microM biotin in the reaction mixture or by prior incubation of the brush border membrane vesicles with an activated 60- to 65-kDa toxin from Bacillus thuringiensis HD-73. The ability of B. thuringiensis toxins to recognize biotin-containing proteins was confirmed by their binding to pyruvate carboxylase, a biotin-containing enzyme, as well as to biotinylated ovalbumin and biotinylated bovine serum albumin but not to their nonbiotinylated counterparts. Activated HD-73 toxin also inhibited the enzymatic activity of pyruvate carboxylase. The biotin binding site is likely contained in domain III of the toxin. Two highly conserved regions within domain III are similar in sequence to the biotin binding sites of avidin, streptavidin, and a biotin-specific monoclonal antibody. In particular, block 4 of the B. thuringiensis toxin contains the YAS biotin-specific motif. On the basis of its N-terminal amino acid sequence, the 120-kDa biotin-containing protein is totally distinct from the 120-kDa aminopeptidase N reported to be a receptor for Cry1Ac toxin.
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Affiliation(s)
- C Du
- School of Biological Sciences, University of Nebraska, Lincoln 68588-0666, USA
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Charles JF, Nielsen-LeRoux C. Les bactéries entomopathogènes: mode d'action sur les larves de moustiques et phénomènes de résistance. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0924-4204(97)86392-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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