Loop replacements with gut-binding peptides in Cry1Ab domain II enhanced toxicity against the brown planthopper, Nilaparvata lugens (Stål)

Shao, Ensi; Lin, Li; Chen, Chen; Chen, Hanze; Zhuang, Haohan; Wu, Songqing; Li, Sha; Guan, Xiong; Huang, Zhaohui

doi:10.1038/srep20106

Cited by 34 publications

(25 citation statements)

References 53 publications

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“…The ultrastructure of the midgut epithelium was examined using a JEOL JEM-2100HC transmission electron microscope (Shao et al, 2016). Larvae fed sodium carbonate buffer (50 mM, pH 9.5) served as a negative control.…”

Section: Preparation Of Midgut Tissues For Transmission Electron MImentioning

confidence: 99%

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Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure

Pan

Zhang

et al. 2018

Cellular Microbiology

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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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Section: Preparation Of Midgut Tissues For Transmission Electron MImentioning

confidence: 99%

“…Ultrathin sections were sliced using a Leica ultramicrotome (EM UC7), stained with uranyl acetate and then lead citrate. The ultrastructure of the midgut epithelium was examined using a JEOL JEM-2100HC transmission electron microscope (Shao et al, 2016).…”

Section: Preparation Of Midgut Tissues For Transmission Electron MImentioning

confidence: 99%

Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure

Pan

Zhang

et al. 2018

Cellular Microbiology

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“…Here, we define the β1‐α8 (Residues 296–319), β4–β5 (Residues 378–383), and β8–β9 (Residues 435–444) loops as A, B, and C loops, respectively, and assign the previously defined Loops 1, 2, and 3, as L1 (β2–β3, Residues 348–352), L2 (β6–β7, Residues 407–409), and L3 (β10–β11, Residues 479–488) loops, respectively [Figs. (D) and ] . The Apex loops in the Cry7Ca1 toxin structure are different from other Cry proteins in length, conformation, and amino acid sequence, despite the moderate sequence conservation of neighboring β‐strands (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…1 and 2). 4,20 The Apex loops in the Cry7Ca1 toxin structure are different from other Cry proteins in length, conformation, and amino acid sequence, despite the moderate sequence conservation of neighboring β-strands (Fig. 3).…”

Section: Resultsmentioning

confidence: 99%

“…They are of great interests for the development of bio‐insecticides with minimal ecological damage and therefore are attractive alternatives to chemical insecticides . Due to their high insecticidal specificity and environmentally friendly characteristics, the Cry proteins have been broadly used to control agricultural insect pests and to acquire specific pest resistance in transgenic plants . Hence, understanding the molecular mechanisms of how Bt Cry proteins achieve insecticidal specificity and efficiency becomes the key to identify and develop proper strategies in better utilizing them in agriculture and other aspects.…”

Section: Introductionmentioning

confidence: 99%

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Crystal structure of Bacillus thuringiensis Cry7Ca1 toxin active against Locusta migratoria manilensis

Jing

Yuan

et al. 2018

Protein Science

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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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Molecular Approaches for Insect Pest Management in Rice

et al. 2021

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This chapter focuses on the progress made in using molecular tools in understanding resistance in rice to insect pests and breeding rice for multiple and durable insect resistance. Currently, molecular markers are being extensively used to tag, map, introgress, and clone plant resistance genes against gall midge, planthoppers, and leafhoppers. Studies on cloned insect resistance genes are leading to a better understanding of plant defense against insect pests under different feeding guilds. While marker-assisted breeding is successfully tackling problems in durable and multiple pest resistance in rice, genomics of plants and insects has identified RNAi-based gene silencing as an alternative approach for conferring insect resistance. The use of these techniques in rice is in the developmental stage, with the main focus on brown planthopper and yellow stem borer. CRISPR-based genome editing techniques for pest control in plants has just begun. Insect susceptibility genes (negative regulators of resistance genes) in plants are apt targets for this approach while gene drive in insect populations, as a tool to study rice-pest interactions, is another concept being tested. Transformation of crop plants with diverse insecticidal genes is a proven technology with potential for commercial success. Despite advances in the development and testing of transgenic rice for insect resistance, no insect-resistant rice cultivar is now being commercially cultivated. An array of molecular tools is being used to study insect-rice interactions at transcriptome, proteome, metabolome, mitogenome, and metagenome levels, especially with reference to BPH and gall midge, and such studies are uncovering new approaches for insect pest management and for understanding population genetics and phylogeography of rice pests. Thus, it is evident that the new knowledge being gained through these studies has provided us with new tools and information for facing future challenges. However, what is also evident is that our attempts to manage rice pests cannot be a one-time effort but must be a continuing one.

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Loop replacements with gut-binding peptides in Cry1Ab domain II enhanced toxicity against the brown planthopper, Nilaparvata lugens (Stål)

Cited by 34 publications

References 53 publications

Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure

Exposure of helices α4 and α5 is required for insecticidal activity of Cry2Ab by promoting assembly of a prepore oligomeric structure

Crystal structure of Bacillus thuringiensis Cry7Ca1 toxin active against Locusta migratoria manilensis

Molecular Approaches for Insect Pest Management in Rice

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