Insecticidal crystal proteins of Bacillus thuringiensis.
01 Jun 1989-Microbiological Research (American Society for Microbiology)-Vol. 53, Iss: 2, pp 242-255
TL;DR: In this article, a classification for crystal protein genes of Bacillus thuringiensis is presented, based on the insecticidal spectra and the amino acid sequences of the encoded proteins.
About: This article is published in Microbiological Research.The article was published on 1989-06-01 and is currently open access. It has received 2044 citations till now. The article focuses on the topics: Delta endotoxin & Bacillus thuringiensis.
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TL;DR: Researchers are reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.
Abstract: During the past decade the pesticidal bacterium Bacillus thuringiensis has been the subject of intensive research. These efforts have yielded considerable data about the complex relationships between the structure, mechanism of action, and genetics of the organism’s pesticidal crystal proteins, and a coherent picture of these relationships is beginning to emerge. Other studies have focused on the ecological role of the B. thuringiensis crystal proteins, their performance in agricultural and other natural settings, and the evolution of resistance mechanisms in target pests. Armed with this knowledge base and with the tools of modern biotechnology, researchers are now reporting promising results in engineering more-useful toxins and formulations, in creating transgenic plants that express pesticidal activity, and in constructing integrated management strategies to insure that these products are utilized with maximum efficiency and benefit.
3,011 citations
TL;DR: Lack of parasitoids in a particular area may have occurred because the diamondback moth is better able than its natural-enemy complex to become established in newly planted cmcifers.
Abstract: In recent years, the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae), has become the most destructive insect of cruciferous plants throughout the world, and the annual cost for managing it is estimated to be US $I billion (168) Members of the plant family Cruciferae occur temperate and tropical climates and represent a diverse, widespread, and important plant group that includes cabbage, broccoli, cauliflower, collards, rapeseed, mustard, and Chinese cabbage, the most important vegetable crop grown in China (90), the most populous country in the world Although the diamondback moth is believed to have originated in the Mediterranean area (64), the source of some of our most important crucifers (185), diamondback moths now occur wherever cmcifers are grown, and this insect is believed to be the most universally distributed of all Lepidoptera (107) Absence of effective natural enemies, especially parasitoids, is believed to be a major cause of the diamondback moth’s pest status in most parts of the world (92) Lack of parasitoids in a particular area may have occurred because the diamondback moth is better able than its natural-enemy complex to become established in newly planted cmcifers Reports on the ability of diamondback moths to migrate long distances are numerous (19, 40, 54, 58, 108, 120,
1,372 citations
TL;DR: A new nomenclature, based on hierarchical clustering using amino acid sequence identity, is proposed, consisting of 133 crystal proteins comprising 24 primary ranks are systematically arranged.
Abstract: The crystal proteins of Bacillus thuringiensis have been extensively studied because of their pesticidal properties and their high natural levels of production. The increasingly rapid characterization of new crystal protein genes, triggered by an effort to discover proteins with new pesticidal properties, has resulted in a variety of sequences and activities that no longer fit the original nomenclature system proposed in 1989. Bacillus thuringiensis pesticidal crystal protein (Cry and Cyt) nomenclature was initially based on insecticidal activity for the primary ranking criterion. Many exceptions to this systematic arrangement have become apparent, however, making the nomenclature system inconsistent. Additionally, the original nomenclature, with four activity-based primary ranks for 13 genes, did not anticipate the current 73 holotype sequences that form many more than the original four subgroups. A new nomenclature, based on hierarchical clustering using amino acid sequence identity, is proposed. Roman numerals have been exchanged for Arabic numerals in the primary rank (e.g., Cry1Aa) to better accommodate the large number of expected new sequences. In this proposal, 133 crystal proteins comprising 24 primary ranks are systematically arranged.
1,167 citations
TL;DR: In this article, a synthetic gene encoding a truncated version of the CryIA(b) protein derived from Bacillus thuringiensis was introduced into immature embryos of an elite line of maize using microprojectile bombardment.
Abstract: We introduced a synthetic gene encoding a truncated version of the CryIA(b) protein derived from Bacillus thuringiensis into immature embryos of an elite line of maize using microprojectile bombardment. This gene was expressed using either the CaMV 35S promoter or a combination of two tissue specific promoters derived from maize. High levels of CryIA(b) protein were obtained using both promoter configurations. Hybrid maize plants resulting from crosses of transgenic elite inbred plants with commercial inbred lines were evaluated for resistance to European corn borer under field conditions. Plants expressing high levels of the insecticidal protein exhibited excellent resistance to repeated heavy infestations of this pest.
931 citations
TL;DR: The use of synthetic organic insecticides developed during the last half of this century may pose risks to human health and can cause environmental damage, Consequently, interest has developed in using alternative strategies for insect pest management, including Bacillus thuringiensis toxins as insecticides.
Abstract: The use of synthetic organic insecticides developed during the last half of this century may pose risks to human health and can cause environmental prob lems. Consequently, interest has developed in using alternative strategies for insect pest management. One contemporary approach that has received atten tion is the development of Bacillus thuringiensis (Bt) toxins as insecticides. B. thuringiensis, a gram-positive bacteria, produces a proteinaceous paraspor al crystalline inclusion during sporulation. Upon ingestion by insects, this crystalline inclusion is solubilized in the midgut, releasing proteins called S-endotoxins. These proteins (protoxins) are activated by midgut proteases, and the activated toxins interact with the larval midgut epithelium causing a disruption in membrane integrity and ultimately leading to insect death. In spite of significant efforts directed towards the study of Bt, its use in pest control is restricted, in part because of the selectivity of Bt and in part because of its moderate efficacy. Attempts to improve these two qualities have met with only moderate success because inadequate effort has been devoted to understanding the molecular basis of selectivity and insecticidal properties of these toxins.
827 citations
References
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TL;DR: An algorithm has been developed which identifies alpha-helices involved in the interactions of membrane proteins with lipid bilayers and which distinguishes them from helices in soluble proteins, and suggests four transmembrane helices and a surface-seeking helix in fragment B, the moiety known to have trans Membrane function.
2,157 citations
TL;DR: The Gram-positive bacterium Bacillus thuringiensis produces proteins which are specifically toxic to a variety of insect species, and modified genes have been derived from bt2, a toxin gene cloned from one Bacillus strain.
Abstract: The Gram-positive bacterium Bacillus thuringiensis produces proteins which are specifically toxic to a variety of insect species. Modified genes have been derived from bt2, a toxin gene cloned from one Bacillus strain. Transgenic tobacco plants expressing these genes synthesize insecticidal proteins which protect them from feeding damage by larvae of the tobacco hornworm.
988 citations
TL;DR: Experiments using this protocol have resulted in mature RO and R1 plants expressing the introduced gene(s), regarded as a major step in the practical application of genetic engineering to the useful modification of food-crop species.
Abstract: We have used particle acceleration by electric discharge to introduce DNA-coated gold particles into meristems of immature soybean seeds. Approximately 2 percent of shoots derived from these meristems via organogenesis were chimeric for expression of the introduced gene. Experiments using this protocol have resulted in mature RO and R1 plants expressing the introduced gene(s). We regard this work as a major step in the practical application of genetic engineering to the useful modification of food-crop species.
742 citations
TL;DR: The structure of an insect control protein gene from Bacillus thuringiensis var.
Abstract: The structure of an insect control protein gene from Bacillus thuringiensis var. kurstaki HD–1 was determined, and truncated forms of the gene that express a functional insecticidal protein were generated. Two of these truncated genes were incorporated into a plant expression vector for Agrobacterium–mediated transformation. Transgenic tomato plants containing the chimeric genes express the insect control protein gene. Such expression confers tolerance to lepidopteran larvae on the transgenic tomato plants and their progeny. These engineered tomato plants represent a significant step to increased selectivity, specificity and efficiency in insect control.
574 citations
TL;DR: With the exception of the Lepidopteran cell line, Choristoneura fumiferana 63 CF1, this soluble crystal delta-endotoxin protein showed no in vitro or in vivo toxicity, and no haemolytic activity.
Abstract: Bacillus thuringiensis var israelensis parasporal crystal delta-endotoxin was purified by ultracentrifugation on a discontinuous sucrose gradient. Native delta-endotoxin crystals showed no detectable toxicity in the vitro and in vivo systems that are described. By contrast alkali-solubilized crystal delta-endotoxin caused rapid cytological and cytopathological changes in Aedes albopictus, Choristoneura fumiferana 63 CF1, Spodoptera frugiperda and Trichoplusia ni cell lines as observed by phase-contrast microscopy and vital staining. Mouse fibroblasts, primary pig lymphocytes and three mouse epithelial carcinoma cell types showed a similar response to the alkali-soluble crystal delta-endotoxin. In addition the soluble crystal delta-endotoxin protein caused haemolysis of rat, mouse, sheep, horse and human erythrocytes. Intravenous administration of the alkali-soluble crystal delta-endotoxin to Balb. c mice at a dose rate of 15-30 micrograms of protein per gram body weight resulted in rapid paralysis followed by death within 12h. Subcutaneous inoculation of 15-30 micrograms of protein per gram body weight resulted in death of suckling mice in 2-3 h. The alkali-solubilized crystal delta-endotoxin was not toxic however, when administered per os. A comparison is made with a similar alkali-soluble fraction from the parasporal crystal delta-endotoxin of B. thuringiensis var kurstaki. With the exception of the Lepidopteran cell line, Choristoneura fumiferana 63 CF1, this soluble crystal delta-endotoxin protein showed no in vitro or in vivo toxicity, and no haemolytic activity.
511 citations