Recombinant Spider Silk in Silkworms for Bombyx-Free Fiber Purity
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Solution Overview
Problem
Existing methods fail to produce high-strength spider silk or spider silk analogs in significant quantities without contamination from lower-strength Bombyx silk, using silkworms as bioreactors.
Innovation Solution
A recombinant DNA construct is used to fuse spider silk fibroin polypeptide sequences with silkworm fibroin genes, allowing homologous recombination to replace native silkworm genes, thereby producing silk that predominantly consists of spider silk or its analogs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If silkworms are used as bioreactors to produce spider silk, then large quantities of silk can be produced, but contamination from lower-strength Bombyx silk occurs
Solution Approach 1:
The patent extracts and replaces the native silkworm fibroin genes with recombinant spider silk genes. By removing the original gene sequence and inserting the desired spider silk gene sequence into the silkworm genome, the contamination from Bombyx silk is eliminated while maintaining high productivity. This is achieved through homologous recombination where the recombinant gene replaces the endogenous gene.
Solution Approach 2:
The patent creates a copy of the spider silk gene sequence and introduces it into the silkworm host. Instead of using the native silkworm genes, a recombinant copy of the spider silk gene is inserted into the silkworm genome, allowing the host to produce spider silk proteins with the desired properties without contamination from the original silkworm silk composition.
2Strength
If native spider silk genes are expressed in silkworms, then spider silk properties are achieved, but the silk fiber does not properly replicate the qualities of native spider silk
Solution Approach 1:
The patent merges the spider silk gene sequence with the silkworm expression system. By combining the recombinant spider silk coding sequence with silkworm genomic elements (promoters, regulatory sequences, and genomic integration sites), the system achieves both the desired spider silk properties and proper silk fiber formation. The fusion of these genetic elements allows for correct protein folding, assembly, and fiber spinning characteristics.
Solution Approach 2:
The patent modifies the genetic parameters by changing the coding sequence from native silkworm genes to recombinant spider silk genes. This parameter change in the DNA sequence results in the production of spider silk proteins with the correct amino acid sequence, enabling proper beta-sheet formation, hydrogen bonding, and fiber morphology that replicate native spider silk qualities.
3Manufacturing precision
If recombinant DNA constructs are used to replace native silkworm genes, then purity of spider silk is improved, but the complexity of the production system increases
Solution Approach 1:
The patent performs preliminary actions by pre-constraining the recombinant DNA construct with homologous sequences before introduction into the silkworm. The recombinant gene is designed with flanking sequences that match the silkworm genome, which facilitates precise integration through homologous recombination. This preliminary design simplifies the overall process by ensuring automatic correct placement and expression without requiring complex post-integration editing.
Solution Approach 2:
The patent uses homologous recombination as an intermediary mechanism to bridge the recombinant DNA construct and the silkworm genome. This natural biological process acts as a mediator that automatically integrates the foreign gene into the host genome at the correct location, simplifying the transformation process compared to direct injection or viral vector methods. The homologous sequences serve as molecular guides that facilitate precise and efficient gene replacement.
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 method enables the production of silk predominantly composed of spider silk or its analogs, replicating its exceptional properties and overcoming contamination issues with Bombyx silk.
Implementation Method 1
A recombinant DNA construct is used to fuse spider silk fibroin polypeptide sequences with silkworm fibroin genes, allowing homologous recombination to replace native silkworm genes
Data Source
AI summary
Disclosed are methods, compositions, and systems for transforming silkworms to produce spider silk and analogs of spider silk. In certain embodiments, the method may include inserting a DNA sequence coding for at least a portion of a spider silk fibroin polypeptide, or an analog of a spider silk fibroin polypeptide, positioned between at least a portion of the 5′ and 3′ ends of a silkworm fibroin gene to generate a fusion gene construct having a sequence that encodes for a polypeptide comprising both spider silk fibroin and silkworm silk fibroin sequences. In certain embodiments, the fused gene is able to replace a native gene present in the silkworm such that the transformed silkworm expresses a polypeptide comprising a spider silk fibroin polypeptide, or an analog thereof, and expresses significantly less of the native silkworm silk.