Towards novel Cry toxins with enhanced toxicity/broader: a new chimeric Cry4Ba / Cry1Ac toxin

Zghal, Raida Zribi; Elleuch, Jihen; Ali, Mamdouh Ben; Darriet, Frédéric; Rebai, Ahmed; Chandre, Fabrice; Jaoua, Samir; Tounsi, Slim

doi:10.1007/s00253-016-7766-3

Cited by 12 publications

(12 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, in Cry1Ac, a deletion of 56 amino acids at the N-terminus, which included helix α-1, increase the toxic activity against Pectinophora gossypiella by 107-fold ( Mandal et al, 2007 ) and against Plutella xylostella and Ostrinia nubilalis by 350-fold ( Tabashnik et al, 2011 ). However, the toxic activity of Cry4Ba against A. aegypti was abolished when more than 38 amino acids were removed from the N-terminus ( Pao-intara et al, 1988 ) and, in the case of chimeric proteins formed by a fusion of N-terminus of Cry4Ba and the C-terminus of Cry1Ac, an increase of toxicity against C. pipiens larvae was observed ( Zghal et al, 2017 ). Although these findings confirm the importance of the N-terminal region in the toxicity of Cry proteins, the N-terminal deletions found in our variants did not affect their toxic activity against A. aegypti or C. quinquefasciatus larvae.…”

Section: Discussionmentioning

confidence: 99%

Toxic Activity, Molecular Modeling and Docking Simulations of Bacillus thuringiensis Cry11 Toxin Variants Obtained via DNA Shuffling

et al. 2018

View full text Add to dashboard Cite

The Cry11 family belongs to a large group of δ-endotoxins that share three distinct structural domains. Among the dipteran-active toxins referred to as three-domain Cry11 toxins, the Cry11Aa protein from Bacillus thuringiensis subsp. israelensis (Bti) has been the most extensively studied. Despite the potential of Bti as an effective biological control agent, the understanding of Cry11 toxins remains incomplete. In this study, five Cry11 variants obtained via DNA shuffling displayed toxic activity against Aedes aegypti and Culex quinquefasciatus. Three of these Cry11 variants (8, 23, and 79) were characterized via 3D modeling and analysis of docking with ALP1. The relevant mutations in these variants, such as deletions, insertions and point mutations, are discussed in relation to their structural domains, toxic activities and toxin-receptor interactions. Importantly, deletion of the N-terminal segment in domain I was not associated with any change in toxic activity, and domain III exhibited higher sequence variability than domains I and II. Variant 8 exhibited up to 3.78- and 6.09-fold higher toxicity to A. aegypti than Cry11Bb and Cry11Aa, respectively. Importantly, variant 79 showed an α-helix conformation at the C-terminus and formed crystals retaining toxic activity. These findings indicate that five Cry11 variants were preferentially reassembled from the cry11Aa gene during DNA shuffling. The mutations described in loop 2 and loop 3 of domain II provide valuable information regarding the activity of Cry11 toxins against A. aegypti and C. quinquefasciatus larvae and reveal new insights into the application of directed evolution strategies to study the genetic variability of specific domains in cry11 family genes.

show abstract

Section: Discussionmentioning

confidence: 99%

Toxic Activity, Molecular Modeling and Docking Simulations of Bacillus thuringiensis Cry11 Toxin Variants Obtained via DNA Shuffling

et al. 2018

View full text Add to dashboard Cite

show abstract

“…More recently, and thanks to the determination of the Cry1Ac1 full-length toxin 3D structure ( [19]; PDB 4W8J), Zghal et al [21] constructed a 116 KDa chimeric toxin called Cry(4Ba-1Ac) by fusing DI-DIV from Cry4Ba to DV-DVII from Cry1Ac1, using PCR amplification and cloning techniques. This represents a unique case in which other domains, apart from Cry toxin toxic domains, have been swapped.…”

Section: Res Res* Res*: Restriction Enzyme Sitementioning

confidence: 99%

“…Although the functions of DIV-DVII are not known, they have been related with crystal formation, toxin stability, and selective solubilization in the insect gut. In addition, it has recently been suggested that Domains V and VII could also be interacting domains with proteins present in gut membranes, and hence be involved in the recognition of receptors of the full toxin [21].…”

Section: Introductionmentioning

confidence: 99%

Making 3D-Cry Toxin Mutants: Much More Than a Tool of Understanding Toxins Mechanism of Action

Vı́lchez

2020

Toxins

View full text Add to dashboard Cite

3D-Cry toxins, produced by the entomopathogenic bacterium Bacillus thuringiensis, have been extensively mutated in order to elucidate their elegant and complex mechanism of action necessary to kill susceptible insects. Together with the study of the resistant insects, 3D-Cry toxin mutants represent one of the pillars to understanding how these toxins exert their activity on their host. The principle is simple, if an amino acid is involved and essential in the mechanism of action, when substituted, the activity of the toxin will be diminished. However, some of the constructed 3D-Cry toxin mutants have shown an enhanced activity against their target insects compared to the parental toxins, suggesting that it is possible to produce novel versions of the natural toxins with an improved performance in the laboratory. In this report, all mutants with an enhanced activity obtained by accident in mutagenesis studies, together with all the variants obtained by rational design or by directed mutagenesis, were compiled. A description of the improved mutants was made considering their historical context and the parallel development of the protein engineering techniques that have been used to obtain them. This report demonstrates that artificial 3D-Cry toxins made in laboratories are a real alternative to natural toxins.

show abstract

“…Alternatively, to circumvent resistance, several novel strategies like gene pyramiding and generation of chimeric toxins ( Zghal et al, 2017 ; Khabbazi et al, 2018 ; Sellami et al, 2018 ; Rathinam et al, 2019 ; Zubair et al, 2019 ; Salim et al, 2020 ); RNAi-mediated knockdown ( Tian et al, 2015 ; Han et al, 2017 ; Luo et al, 2017 ; Ni et al, 2017 ; Shen et al, 2017 ); CRISPR/Cas9 mediated genome editing ( Zhang et al, 2018 ; Bisht et al, 2019 ; Tyagi et al, 2020 ) and multiomic approaches ( Du et al, 2018 ; Peng et al, 2020 ) for the management of insect resistance have also become an integral part of pest management through biotechnology.…”

Section: Introductionmentioning

confidence: 99%

Exploitation of Novel Bt ICPs for the Management of Helicoverpa armigera (Hübner) in Cotton (Gossypium hirsutum L.): A Transgenic Approach

et al. 2021

View full text Add to dashboard Cite

Cotton is a commercial crop of global importance. The major threat challenging the productivity in cotton has been the lepidopteron insect pest Helicoverpa armigera or cotton bollworm which voraciously feeds on various plant parts. Biotechnological interventions to manage this herbivore have been a universally inevitable option. The advent of plant genetic engineering and exploitation of Bacillus thuringiensis (Bt) insecticidal crystal proteins (ICPs) marked the beginning of plant protection in cotton through transgenic technology. Despite phenomenal success and widespread acceptance, the fear of resistance development in insects has been a perennial concern. To address this issue, alternate strategies like introgression of a combination of cry protein genes and protein-engineered chimeric toxin genes came into practice. The utility of chimeric toxins produced by domain swapping, rearrangement of domains, and other strategies aid in toxins emerging with broad spectrum efficacy that facilitate the avoidance of resistance in insects toward cry toxins. The present study demonstrates the utility of two Bt ICPs, cry1AcF (produced by domain swapping) and cry2Aa (produced by codon modification) in transgenic cotton for the mitigation of H. armigera. Transgenics were developed in cotton cv. Pusa 8–6 by the exploitation of an apical meristem-targeted in planta transformation protocol. Stringent trait efficacy-based selective screening of T1 and T2 generation transgenic plants enabled the identification of plants resistant to H. armigera upon deliberate challenging. Evaluation of shortlisted events in T3 generation identified a total of nine superior transgenic events with both the genes (six with cry1AcF and three with cry2Aa). The transgenic plants depicted 80–100% larval mortality of H. armigera and 10–30% leaf damage. Molecular characterization of the shortlisted transgenics demonstrated stable integration, inheritance and expression of transgenes. The study is the first of its kind to utilise a non-tissue culture-based transformation strategy for the development of stable transgenics in cotton harbouring two novel genes, cry1AcF and cry2Aa for insect resistance. The identified transgenic events can be potential options toward the exploitation of unique cry genes for the management of the polyphagous insect pest H. armigera.

show abstract

Towards novel Cry toxins with enhanced toxicity/broader: a new chimeric Cry4Ba / Cry1Ac toxin

Cited by 12 publications

References 42 publications

Toxic Activity, Molecular Modeling and Docking Simulations of Bacillus thuringiensis Cry11 Toxin Variants Obtained via DNA Shuffling

Toxic Activity, Molecular Modeling and Docking Simulations of Bacillus thuringiensis Cry11 Toxin Variants Obtained via DNA Shuffling

Making 3D-Cry Toxin Mutants: Much More Than a Tool of Understanding Toxins Mechanism of Action

Exploitation of Novel Bt ICPs for the Management of Helicoverpa armigera (Hübner) in Cotton (Gossypium hirsutum L.): A Transgenic Approach

Contact Info

Product

Resources

About