Variant Bt Polypeptides for Broad-Spectrum Insect Resistance
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Solution Overview
Problem
Existing genetically engineered crops provide resistance to only a narrow range of economically important insect pests, necessitating the development of new Bacillus thuringiensis (Bt) toxins with improved insecticidal activity against insects from the orders Lepidoptera and Coleoptera, and biopesticides with broader activity against various insect pests.
Innovation Solution
Development of recombinant nucleic acids encoding variant pesticidal polypeptides, including modified Cry1B polypeptides with enhanced activity, and their use in transforming plants and microorganisms to produce transgenic plants expressing these polypeptides, thereby providing improved insect resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If genetically engineered crops produce pesticidal proteins from Bacillus, then insect resistance is provided, but the spectrum of resistance is narrow and limited to specific insect pests
Solution Approach 1:
The patent creates a single pesticidal polypeptide that performs multiple functions by targeting both Lepidoptera and Coleoptera insect orders simultaneously. This is achieved through designing a chimeric protein structure that combines functional domains from different Bt toxins, enabling one protein to bind to and disrupt gut epithelial cells of diverse insect pests including corn earworm, fall armyworm, European corn borer, and Colorado potato beetle.
Solution Approach 2:
The invention merges pesticidal activity domains from different Bacillus thuringiensis toxins into a single polypeptide construct. The chimeric structure integrates functional regions that recognize and bind to receptors in both Lepidopteran and Coleopteran insect guts, combining the effects of multiple separate toxins into one unified molecule with broader spectrum activity.
2Productivity
If broad-spectrum chemical insecticides are used, then pest control efficacy is achieved, but environmental hazards and pollution increase
Solution Approach 1:
The patent replaces synthetic chemical insecticides with a biologically derived pesticidal polypeptide produced through genetic engineering. This substitution uses a recombinant DNA-encoded protein that mimics the mode of action of natural Bt toxins, providing effective pest control through biological mechanisms rather than broad-spectrum chemical toxicity, thereby reducing environmental contamination and non-target effects.
Solution Approach 2:
The invention modifies the pesticidal polypeptide sequence through site-directed mutagenesis and codon optimization to enhance its stability, expression levels, and insecticidal activity. These parameter changes in the protein structure and genetic sequence improve efficacy against target pests while maintaining the environmental benefits of a biologically-based control agent compared to synthetic chemicals.
3Reliability
If existing Bt toxins are used, then insecticidal activity is provided, but activity against certain pests like corn earworm and fall armyworm is insufficient
Solution Approach 1:
The patent applies local quality modifications by introducing specific point mutations at critical positions within the pesticidal polypeptide structure. These localized changes in amino acid sequence at specific sites enhance binding affinity to insect gut receptors and improve toxicological activity against resistant pest populations, particularly corn earworm and fall armyworm, without compromising overall protein stability or function.
Data Source
AI summary
The disclosure provides nucleic acids, and variants and fragments thereof, derived from strains of Bacillus thuringiensis encoding variant polypeptides having increased pesticidal activity against insect pests, including Lepidoptera and Coleopteran. Particular embodiments of the disclosure provide isolated nucleic acids encoding pesticidal proteins, pesticidal compositions, DNA constructs, and transformed microorganisms and plants comprising a nucleic acid of the embodiments. These compositions find use in methods for controlling pests, especially plant pests.