In Vivo Crystallization of Three-Domain Cry Toxins

Adalat, Rooma; Saleem, Faiza; Crickmore, N.; Naz, Shagufta; Shakoori, A. R.

doi:10.3390/toxins9030080

Cited by 22 publications

(25 citation statements)

References 80 publications

(118 reference statements)

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“…Furthermore, although there are many structural similarities, some physiological characteristics between Cry and PirA vp /PirB vp toxins may be different. For example, the Cry protoxins generally form crystals in the mother cell compartment [ 45 , 46 ]. Since the crystals have to be solubilized in the gut of insect larvae to become biologically active, this ability of the protoxins to crystallize may decrease their susceptibility to premature proteolytic degradation [ 45 ].…”

Section: The Structural Similarity Between V Parahaemolmentioning

confidence: 99%

Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirAvp and PirBvp Toxins

2017

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In aquaculture, shrimp farming is a popular field. The benefits of shrimp farming include a relatively short grow-out time, high sale price, and good cost recovery. However, outbreaks of serious diseases inflict serious losses, and acute hepatopancreatic necrosis disease (AHPND) is an emerging challenge to this industry. In South American white shrimp (Penaeus vannamei) and grass shrimp (Penaeus monodon), this disease has a 70–100% mortality. The pathogenic agent of AHPND is a specific strain of Vibrio parahaemolyticus which contains PirAvp and PirBvp toxins encoded in the pVA1 plasmid. PirAvp and PirBvp have been shown to cause the typical histological symptoms of AHPND in infected shrimps, and in this review, we will focus on our structural understanding of these toxins. By analyzing their structures, a possible cytotoxic mechanism, as well as strategies for anti-AHPND drug design, is proposed.

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Section: The Structural Similarity Between V Parahaemolmentioning

confidence: 99%

Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirAvp and PirBvp Toxins

2017

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“…S3). This high sequence similarity strongly suggests a conserved function with the crystallization domain of Cry4-type proteins, which is essential for their inclusion in the parasporal crystal (54). Interestingly, the genes encoding these proteins are located downstream of those encompassing conserved domains ones, with a short intergenic distance (max.…”

Section: Novel Insecticidal Toxinsmentioning

confidence: 99%

A Novel Antidipteran Bacillus thuringiensis Strain: Unusual Cry Toxin Genes in a Highly Dynamic Plasmid Environment

Fayad

Kambris

Chamy

et al. 2021

Appl Environ Microbiol

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Bacillus thuringiensis emerged as a major bioinsecticide on the global market. It offers a valuable alternative to chemical products classically utilized to control pest insects. Despite the efficiency of several strains and products available on the market, the scientific community is always on the lookout for novel toxins that can replace or supplement the existing products. In this study, H3, a novel B. thuringiensis strain showing mosquitocidal activity, was isolated from Lebanese soil and characterized at an in vivo, genomic and proteomic levels. H3 parasporal crystal is toxic on its own but displays an unusual killing profile with a higher LC50 than the reference B. thuringiensis serovar israelensis crystal proteins. In addition, H3 has a different toxicity order: it is more toxic to Aedes albopictus and Anopheles gambiae than to Culex pipiens. Whole genome sequencing and crystal analysis revealed that H3 can produce eleven novel Cry proteins, eight of which are assembled in genes with an orf1-gap-orf2 organization, where orf2 is a potential Cry4-type crystallization domain. Moreover, pH3-180, the toxin-carrying plasmid, holds a wide repertoire of mobile genetic elements that amount to ca. 22% of its size., including novel insertion sequences and class II transposable elements Two other large plasmids present in H3 carry genetic determinants for the production of many interesting molecules - such as chitinase, cellulase and bacitracin - that may add up to H3 bioactive properties. This study therefore reports a novel mosquitocidal Bacillus thuringiensis strain with unusual Cry toxin genes in a rich mobile DNA environment. IMPORTANCE Bacillus thuringiensis, a soil entomopathogenic bacteria, is at the base of many sustainable eco-friendly bio-insecticides. Hence stems the need to continually characterize insecticidal toxins. H3 is an anti-dipteran B. thuringiensis strain, isolated from Lebanese soil, whose parasporal crystal contains eleven novel Cry toxins and no Cyt toxins. In addition to its individual activity, H3 showed potential as a co-formulant with classic commercialized B. thuringiensis products, to delay the emergence of resistance and to shorten the time required for killing. On a genomic level, H3 holds three large plasmids, one of which carries the toxin-coding genes, with four occurrences of the distinct orf1-gap-orf2 organization. Moreover, this plasmid is extremely rich in mobile genetic elements, unlike its two co-residents. This highlights the important underlying evolutionary traits between toxin-carrying plasmids and the adaptation of a B. thuringiensis strain to its environment and insect host spectrum.

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“…In this study, we describe a nematode-active Bt Cry protein, Cry14Ab, that is highly active against C. elegans. We show that Cry14Ab is somewhat unusual compared to many insecticidal Cry proteins in that the C-terminal half of the protein, commonly referred to as the crystallization region 20 , is not easily removed in vitro by common proteases 21 . However, in other ways, Cry14Ab is typical of Cry proteins in that it associates with the nematode intestine and causes damage to the intestine, consistent with the mechanism of action of insecticidal Cry proteins.…”

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confidence: 91%

A Bacillus thuringiensis Cry protein controls soybean cyst nematode in transgenic soybean plants

et al. 2021

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Plant-parasitic nematodes (PPNs) are economically important pests of agricultural crops, and soybean cyst nematode (SCN) in particular is responsible for a large amount of damage to soybean. The need for new solutions for controlling SCN is becoming increasingly urgent, due to the slow decline in effectiveness of the widely used native soybean resistance derived from genetic line PI 88788. Thus, developing transgenic traits for controlling SCN is of great interest. Here, we report a Bacillus thuringiensis delta-endotoxin, Cry14Ab, that controls SCN in transgenic soybean. Experiments in C. elegans suggest the mechanism by which the protein controls nematodes involves damaging the intestine, similar to the mechanism of Cry proteins used to control insects. Plants expressing Cry14Ab show a significant reduction in cyst numbers compared to control plants 30 days after infestation. Field trials also show a reduction in SCN egg counts compared with control plants, demonstrating that this protein has excellent potential to control PPNs in soybean.

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In Vivo Crystallization of Three-Domain Cry Toxins

Cited by 22 publications

References 80 publications

Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirAvp and PirBvp Toxins

Structural Insights into the Cytotoxic Mechanism of Vibrio parahaemolyticus PirAvp and PirBvp Toxins

A Novel Antidipteran Bacillus thuringiensis Strain: Unusual Cry Toxin Genes in a Highly Dynamic Plasmid Environment

A Bacillus thuringiensis Cry protein controls soybean cyst nematode in transgenic soybean plants

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