A system for the directed evolution of the insecticidal protein from Bacillus thuringiensis

Ishikawa, Hiroshi; Hoshino, Yasushi; Motoki, Yutaka; Kawahara, T.; Kitajima, Mika; Kitami, Madoka; Watanabe, Ayako; Bravo, Alejandra; Soberón, Mário; Honda, Atsuko; Yaoi, Katsuro; Satō, Ryōichi

doi:10.1007/s12033-007-0001-9

Cited by 29 publications

(38 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The level to which rational design of toxins is possible is shown by the engineering of toxicity toward mosquito larvae into the lepidopteran-specific toxin Cry1Aa (Liu and Dean, 2006). Alternatively, a directed evolution system based on phage display technology for producing toxins with improved binding to a receptor, and thus increased toxicity, has been described (Ishikawa et al, 2007).…”

Section: Mutagenesis Of Three-domain Cry Toxinsmentioning

confidence: 99%

Biotechnological Prospects for Engineering Insect-Resistant Plants

Gatehouse

2008

Plant Physiology

194

View full text Add to dashboard Cite

Insect-resistant crops have been one of the major successes of applying plant genetic engineering technology to agriculture; cotton (Gossypium hirsutum) resistant to lepidopteran larvae (caterpillars) and maize (Zea mays) resistant to both lepidopteran and coleopteran larvae (rootworms) have become widely used in global agriculture and have led to reductions in pesticide usage and lower production costs (Toenniessen et al., 2003;Brookes and Barfoot, 2005).The source of the insecticidal toxins produced in commercial transgenic plants is the soil bacterium Bacillus thuringiensis (Bt). Bt strains show differing specificities of insecticidal activity toward pests, and constitute a large reservoir of genes encoding insecticidal proteins, which are accumulated in the crystalline inclusion bodies produced by the bacterium on sporulation (Cry proteins, Cyt proteins) or expressed during bacterial growth (Vip proteins). The threedomain Cry proteins have been extensively studied; their mechanism of action involves a proteolytic activation step, which occurs in the insect gut after ingestion, followed by interaction of one or both of domains II and III with ''receptors'' on the surface of cells of the insect gut epithelium. This interaction leads to oligomerization of the protein, and domain I is then responsible for the formation of an open channel through the cell membrane . The resulting ionic leakage destroys the cell, leading to breakdown of the gut, bacterial proliferation, and insect death.However, not all pests are adequately targeted by the Bt toxins used at present, and there is still a need to develop solutions to specific problems, such as resistance to sap-sucking pests and pests of stored products. This Update will review some developments to the basic Bt strategy and selected alternative methods for engineering insect resistance.

show abstract

Section: Mutagenesis Of Three-domain Cry Toxinsmentioning

confidence: 99%

Biotechnological Prospects for Engineering Insect-Resistant Plants

Gatehouse

2008

Plant Physiology

194

View full text Add to dashboard Cite

show abstract

“…Using this approach, novel toxins have been generated that exhibit improved activity toward specific insect pests. Previous studies have reported the construction of a library of Cry1Aa toxin Domain II Loop 2 sequences that was displayed on T7 phages and used to evaluate the binding affinity toward the Bombyx mori cadherin receptor [48]. After five rounds of selection, a Cry1Aa mutant containing a mutated Loop 2 in Domain II was obtained that exhibited a 6-fold increase in the insecticidal activity against B. mori , indicating that mutations in this region may affect Cry toxin binding to the receptor [48].…”

Section: Biotechnology Strategies To Speed In Vitro Molecular Evolmentioning

confidence: 99%

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

Lucena

Pelegrini

Martins-de-Sa

et al. 2014

Toxins

View full text Add to dashboard Cite

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.

show abstract

“…Directed evolution system based on phage display technology for producing toxins with improved binding to a receptor, and thus increased toxicity, has also been described (Ishikawa et al 2007). …”

Section: Engineering Of Novel Cry Proteinsmentioning

confidence: 99%

Genetic Improvement of Bt Strains and Development of Novel Biopesticides

Sanchis¹

2012

Bacillus Thuringiensis Biotechnology

View full text Add to dashboard Cite

This review describes how recombinant DNA technology has been used to improve Bacillus thuringiensis (Bt) products and overcome a number of the problems associated with Bt-based insect control measures. It will discuss how the knowledge of the genetics of Bt and of its insecticidal toxin genes, the understanding of their regulation and the development of cloning vectors has made possible the continuing improvement of first generation products. Several examples describing how biotechnology has been used to increase the production of insecticidal proteins in Bt, their persistence in the field by protecting them against UV degradation or to construct non-viable genetically modified strains, will be presented.

show abstract

A system for the directed evolution of the insecticidal protein from Bacillus thuringiensis

Cited by 29 publications

References 54 publications

Biotechnological Prospects for Engineering Insect-Resistant Plants

Biotechnological Prospects for Engineering Insect-Resistant Plants

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

Genetic Improvement of Bt Strains and Development of Novel Biopesticides

Contact Info

Product

Resources

About