Modified Cry Toxin Variants for Resistant Pest Control
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Solution Overview
Problem
The intensive use of B. thuringiensis-based insecticides has led to resistance in field populations of certain pests, particularly the diamondback moth, due to mechanisms like reduced toxin binding to midgut receptors, which can confer cross-resistance to other toxins.
Innovation Solution
The development of novel genes encoding pesticidal proteins, such as those from Bacillus thuringiensis, which can be used to create transgenic plants or bacteria with enhanced pest resistance, including nucleotide and amino acid sequences that encode proteins with at least 95% sequence identity to known pesticidal sequences, to produce organisms with improved pesticidal activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Bacillus thuringiensis-based insecticides are intensively used, then pest control effectiveness is improved, but pest resistance develops reducing long-term efficacy
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of Cry toxins to create variants with altered binding characteristics. Specifically, the invention modifies residues in domains II and III of the toxin structure, which are critical for receptor binding, thereby changing the interaction parameters with pest midgut receptors to overcome resistance mechanisms while maintaining insecticidal activity
Solution Approach 2:
The patent employs composite materials by creating chimeric toxins that combine functional domains from different Cry toxin variants. The invention integrates receptor-binding domains from resistance-breaking variants with core toxic domains from highly active variants, producing composite toxin molecules that simultaneously overcome resistance and maintain potent insecticidal effects
2Reliability
If novel pesticidal proteins with at least 95% sequence identity are developed, then pesticidal activity is maintained, but resistance development risk increases
Solution Approach 1:
The patent applies local quality by making targeted modifications specifically in the receptor-binding domains (domains II and III) of the toxin while preserving the core toxic domain (domain I). This localized modification strategy maintains high overall sequence identity (≥95%) and thus pesticidal activity, while altering the specific interaction interface with pest receptors to reduce resistance development risk
3Reliability
If transgenic plants expressing pesticidal proteins are produced, then pest resistance in plants is enhanced, but complexity of genetic constructs increases
Solution Approach 1:
The patent applies the taking out principle by isolating and expressing only the essential coding sequences of the modified Cry toxin genes in transgenic plants. The invention extracts the core functional elements (domains I, II, and III) required for pesticidal activity and resistance-breaking properties, excluding non-essential sequences, thereby enhancing pest resistance while minimizing genetic construct complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These novel genetic constructs enable the production of organisms with sustained pesticidal activity against lepidopteran, coleopteran, and nematode pests, reducing the risk of resistance development and enhancing agricultural yield by providing long-term pest control.
Implementation Method 1
The ingested protoxin is hydrolyzed by proteases in the insect digestive tract to an active toxic molecule.
Implementation Method 2
This toxin binds to apical brush border receptors in the midgut of the target larvae and inserts into the apical membrane creating ion channels or pores, resulting in larval death.
Data Source
AI summary
Compositions and methods for conferring pesticidal activity to bacteria, plants, plant cells, tissues and seeds are provided. Compositions comprising a coding sequence for a toxin polypeptide are provided. The coding sequences can be used in DNA constructs or expression cassettes for transformation and expression in plants and bacteria. Compositions also comprise transformed bacteria, plants, plant cells, tissues, and seeds. In particular, isolated toxin nucleic acid molecules are provided. Additionally, amino acid sequences corresponding to the polynucleotides are encompassed, and antibodies specifically binding to those amino acid sequences. In particular, the present invention provides for isolated nucleic acid molecules comprising nucleotide sequences encoding the amino acid sequence shown in SEQ ID NO:50-96, or the nucleotide sequence set forth in SEQ ID NO:1-47, as well as variants and fragments thereof.