Residue 544 in Domain III of the Bacillus thuringiensis Cry1Ac Toxin is Involved in Protein Structure Stability

Liu, Yong Le; Wang, Qin Yun; Wang, Fa Xiang; Ding, Xue; Li, Xia

doi:10.1007/s10930-010-9271-3

Cited by 7 publications

(3 citation statements)

References 19 publications

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“…A similar observation was found at mutant T542N in loop β16-β17 within the conserved block 4 of Cry1Ac: the insecticidal activity was increased against S. exigua larvae [61]. Meanwhile, it was reported that residue Trp544 in Cry1Ac loop β18-β19 has an influence on maintaining toxin stability towards H. armigera [62]. Domain III exhibits not only similar functional role as domain II in receptor recognition and binding, but also insecticidal specificity and stability that could be considered as its unique feature.…”

Section: Cry Toxinssupporting

confidence: 61%

Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

Wang

Zhou

et al. 2014

Toxins

145

112

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Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type α-PFTs, Cyt toxin type β-PFTs and aerolysin type β-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively.

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Section: Cry Toxinssupporting

confidence: 61%

Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

Wang

Zhou

et al. 2014

Toxins

145

112

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“…Although the mutant W544F showed no change in its toxicity, which remained the same, it showed greater stability compared with the ultraviolet (UV) radiation exposure than its parental protein. 37 Lucena et al also reported in 2014 the importance of β16-β17 regions. In this study, they made mutations in Cry1Ac , increasing the toxic activity in 1.4 times compared with Spodoptera exigua , where they conclude the implication of domain III in the aspects mentioned above.…”

Section: Resultsmentioning

confidence: 94%

Generation of Cry11 Variants of Bacillus thuringiensis by Heuristic Computational Modeling

Pinzón-Reyes

Sierra-Bueno

Suárez-Barrera

et al. 2020

Evol Bioinform Online

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Directed evolution methods mimic in vitro Darwinian evolution, inducing random mutations and selective pressure in genes to obtain proteins with enhanced characteristics. These techniques are developed using trial-and-error testing at an experimental level with a high degree of uncertainty. Therefore, in silico modeling of directed evolution is required to support experimental assays. Several in silico approaches have reproduced directed evolution, using statistical, thermodynamic, and kinetic models in an attempt to recreate experimental conditions. Likewise, optimization techniques using heuristic models have been used to understand and find the best scenarios of directed evolution. Our study uses an in silico model named HeurIstics DirecteD EvolutioN, which is based on a genetic algorithm designed to generate chimeric libraries from 2 parental genes, cry11Aa and cry11Ba, of Bacillus thuringiensis. These genes encode crystal-shaped δ-endotoxins with 3 conserved domains. Cry11 toxins are of biotechnological interest because they have shown to be effective as biopesticides for disease-spreading vectors. With our heuristic model, we considered experimental parameters such as DNA fragmentation length, number of generations or simulation cycles, and mutation rate, to get characteristics of Cry11 chimeric libraries such as percentage of population identity, truncation of variants obtained from the presence of internal stop codons, percentage of thermodynamic diversity, and stability of variants. Our study allowed us to focus on experimental conditions that may be useful for the design of in vitro and in silico experiments of directed evolution with Cry toxins of 3 conserved domains. Furthermore, we obtained in silico libraries of Cry11 variants, in which structural characteristics of wild Cry families were observed in a review of a sample of in silico sequences. We consider that future studies could use our in silico libraries and heuristic computational models, as the one suggested here, to support in vitro experiments of directed evolution.

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“…However, in Cry8Ka5, the negative charge of glutamate (E538) in this region disrupts the interaction with D520 (Figure 7). In the loops of the three Domains, some residues have been characterized as important for Cry protein toxicity due to their involvement in the interaction with insect receptors [72,87,99,100]. Domain III is the smallest of the three Domains and has been reported to function as a receptor binding site for GPI-ALP, GPI-APN [41,65] and Gal-NAc [31].…”

Section: In Silico Analyses Of Cry and Mutant Toxins For The Contrmentioning

confidence: 99%

Molecular Approaches to Improve the Insecticidal Activity of Bacillus thuringiensis Cry Toxins

Lucena

Pelegrini

Martins-de-Sa

et al. 2014

Toxins

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Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity.

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Residue 544 in Domain III of the Bacillus thuringiensis Cry1Ac Toxin is Involved in Protein Structure Stability

Cited by 7 publications

References 19 publications

Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

Generation of Cry11 Variants of Bacillus thuringiensis by Heuristic Computational Modeling

Molecular Approaches to Improve the Insecticidal Activity of Bacillus thuringiensis Cry Toxins

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