Protease-Stable BtBooster Peptides for Insect Midgut Stability
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Solution Overview
Problem
The narrow spectrum of activity of specific Bacillus thuringiensis (Bt) toxins limits the efficacy of microbial insecticides, requiring additional chemical pesticide applications for effective pest control, and existing Bt synergists are unstable in insect midgut digestive juices, reducing their potency.
Innovation Solution
Derivatives of BtBooster (BtB), specifically protease-stable cadherin fragments like Ms-CR12(PS) and Ms-CR10-12(PS), are developed to enhance the stability and potentiating activity of Bt proteins in insect midguts, allowing for improved insect control by combining with Bt spores and crystals and being expressed in transgenic plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specific Bt toxins are used for insect control, then safety and selectivity are improved, but the spectrum of activity is narrowed and efficacy is reduced
Solution Approach 1:
The patent introduces BtBooster peptides as intermediary molecules that mediate between Bt toxins and insect cadherin receptors. These peptides enhance toxin binding affinity and expand the range of insect species affected, thereby increasing the spectrum of activity while maintaining the safety and selectivity of specific Bt toxins
Solution Approach 2:
The invention creates composite pesticidal formulations combining Bt toxins with BtBooster peptides. This composite approach allows the mixture to exhibit enhanced efficacy and broader spectrum of activity compared to pure Bt toxins, while maintaining the safety profile of the biological agent
2Strength
If existing Bt synergists are applied to enhance toxin potency, then the toxicity of Bt proteins is increased, but stability in insect midgut digestive juices is reduced
Solution Approach 1:
The patent modifies the chemical parameters of BtBooster peptides through protease resistance engineering and structural optimization. These parameter changes include amino acid substitutions that confer protease resistance, allowing the peptides to maintain stability in the harsh environment of insect midgut digestive juices while preserving their toxin-enhancing function
3Productivity
If additional chemical pesticides are applied to achieve adequate pest control, then efficacy is improved, but safety and environmental friendliness are reduced
Solution Approach 1:
The BtBooster peptides act as intermediaries that amplify the effectiveness of biological Bt toxins, enabling adequate pest control to be achieved with lower doses of safe biological agents instead of requiring additional harmful chemical pesticides
Solution Approach 2:
The composite formulation of Bt toxins with BtBooster peptides creates a enhanced biological pesticide that achieves superior pest control efficacy, replacing the need for additional chemical pesticide applications and thereby reducing harmful environmental factors
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
The modified BtB derivatives significantly enhance the toxicity of Bt proteins against key pest species, including Helicoverpa zea and Spodoptera exigua, by increasing stability in insect midguts and reducing the amount of Bt toxin required for effective larval mortality, thus overcoming resistance and extending the host range of Bt biopesticides.
Implementation Method 1
BtBooster can be mixed with commercial formulations of Bt to increase the value of the formulations. BtBooster can also be co-expressed with Bt toxin in Bt transgenic plants to offer better pest protection.
Data Source
AI summary
This invention relates in part to modifying BtBooster (BtB) peptides, in part to increase their stability in insect midgut digestive juices. Some preferred embodiments of BtB have removed proteinase cleavage sites resulting in increased stability of the modified BtB in the insect gut, while retaining the ability to enhance B.t. proteins for improved insect control. In some preferred embodiments, the protease-stable BtB is used in combination with B.t. spores and/or crystals comprising a Cry protein. Also reported herein is the significant and increased enhancement of Bt toxins against relatively Bt-tolerant insects (Helicoverpa zea, Spodoptera exigua and Agrotis ipsilon), when used with BtBs. We also describe increased toxin enhancement with cadherin fragments that are stabilized against over-digestion by insect midgut proteinases. We also report enhancement of Bt Cry1F toxin by cadherin fragments.