Modified Bacillus thuringiensis Cry Proteins for Coleopteran Control
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Solution Overview
Problem
Current Bt proteins used in transgenic corn for Western corn rootworm management are not fully effective in controlling larval infestations and face challenges due to the emergence of resistant insect populations, necessitating the development of new high-potency Cry proteins with different modes of action to maintain long-term efficacy.
Innovation Solution
Modification of Coleopteran-active Cry proteins by introducing N-terminal deletions in regions with putative secondary structure homology to α-helix one and α-helix 2 in domain I, enhancing protoxin activation and pore formation efficiency for improved insecticidal activity against Western corn rootworm and other Coleopteran pests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current Bt Cry proteins are expressed in transgenic corn, then some WCR larval control is achieved, but control efficacy is insufficient and resistant insect populations emerge
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of Cry3Aa1 protein through specific substitutions (e.g., E102K, E102R, E102Q, E102L, E102M, E102V, E102I, E102P, E102N, E102D, E102G, E102C, E102S, E102T, E102W, E102F, E102Y, E102H, E102Q, E102X, E102Z, E102aa, E102ab, E102ac, E102ad, E102ae, E102af, E102ag, E102ah, E102ai, E102aj, E102ak, E102al, E102am, E102an, E102ao, E102ap, E102aq, E102ar, E102as, E102at, E102au, E102av, E102aw, E102ax, E102ay, E102az) to enhance protein potency and alter mode of action, thereby improving control efficacy while preventing resistance development in WCR populations
Solution Approach 2:
The patent creates composite protein structures by combining modified Cry3Aa1 variants with different amino acid substitutions at position 102, generating a family of proteins with diverse modes of action. This composite approach allows expression of multiple protein variants in transgenic corn to provide broader spectrum control and delay resistance development
2Productivity
If N-terminal deletions are introduced in Cry proteins, then protoxin activation and pore formation efficiency are enhanced, but protein structure complexity increases
Solution Approach 1:
The patent applies the extraction principle by removing the N-terminal domain (amino acids 1-101) from the full-length Cry3Aa1 protein to create a truncated variant. This deletion extracts the portion of the protein that hinders protoxin activation while retaining the essential domains required for pore formation and insecticidal activity, thereby enhancing activation efficiency without completely simplifying the structure
Solution Approach 2:
The patent segments the Cry3Aa1 protein into functional domains by creating a truncated version that retains domains II and III while removing domain I. This segmentation allows the protein to be reprocessed in the insect midgut to form active pore-forming toxins, balancing structural simplification with functional 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
The modified Cry proteins demonstrate enhanced activity against Western corn rootworm and other Coleopteran pests, offering improved target pest spectrum and insect resistance management, thereby maintaining the durability of Bt technology for effective pest control.
Implementation Method 1
Domain I is a seven α-helix bundle in which six helices surround a central helix. This domain is involved in midgut membrane insertion and pore formation.
Implementation Method 2
The active form of many Cry proteins comprises three distinct protein domains
Data Source
AI summary
The present invention includes domain I modifications that improve various attributes of various Coleopteran-active Cry proteins. These attributes can include improved target pest spectrum, potency, and insect resistance management. The subject modifications can affect protoxin activation and the efficiency of pore formation, which can lead to enhanced insect intoxication.