Guide RNA-Trapped Genome Editing for Targeted Donor Insertion
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Solution Overview
Problem
Current methods for genome modification in cells, particularly in plants, are inefficient and time-consuming, requiring extensive screening to achieve targeted insertion of donor polynucleotides at specific genomic sites.
Innovation Solution
The use of gene expression cassettes containing non-functional promoters, combined with site-specific promoter activation complexes, to drive robust expression of selectable markers, facilitating marker-based selection and enhancing the efficiency of donor polynucleotide insertion through genomic crossovers, inversions, and relocations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional site specific nuclease methods are used to create double strand breaks and rely on cell machinery repair with donor polynucleotide, then the method can achieve targeted insertion, but the process is inefficient and requires extensive screening of numerous events
Solution Approach 1:
The patent introduces a protein mediator that binds to the guide RNA and facilitates the transfer of the donor polynucleotide to the genomic target site. This intermediary protein complex enhances the efficiency of donor polynucleotide integration by directly mediating the insertion process rather than relying solely on cell repair machinery, thereby resolving the contradiction between reliability of targeted insertion and productivity of the process
Solution Approach 2:
The patent replaces the natural cell repair mechanism (which is slow and inefficient) with an engineered protein-mediated system that actively facilitates donor polynucleotide integration. The protein mediator substitutes for the passive reliance on cell machinery, providing an active, controlled mechanism that significantly improves insertion efficiency while maintaining targeted accuracy
2Manufacturing precision
If traditional nuclease methods create double strand breaks and rely on homologous recombination, then targeted modification is achieved, but the process is time-consuming and negatively impacts product development timelines
Solution Approach 1:
The patent employs preliminary action by introducing the protein mediator and guide RNA complex before the actual insertion event. The mediator is pre-positioned and activated to facilitate rapid donor polynucleotide integration upon encountering the target site, thereby reducing the overall time required for genomic modification while maintaining precision
Solution Approach 2:
The patent changes the key parameter of insertion mechanism from passive homologous recombination to active protein-mediated transfer. This parameter change transforms the process from a slow, random walk-based integration to a directed, enzyme-facilitated transfer, significantly reducing modification time while preserving genomic targeting precision
3Measurement precision
If extensive screening of numerous events is performed to identify and isolate correct insertions, then accurate targeted modification is achieved, but the process becomes inefficient and time-consuming
Solution Approach 1:
The patent incorporates feedback mechanisms through selectable markers or fluorescent reporters that provide immediate visual or functional confirmation of successful insertion. This feedback allows for rapid identification and selection of correctly modified cells without requiring extensive screening, thereby maintaining insertion site accuracy while dramatically improving screening efficiency
Solution Approach 2:
The patent utilizes fluorescent reporters or color-changing selectable markers that provide visual feedback for successful insertion events. This allows for rapid, eye-based screening and selection of correctly modified cells, eliminating the need for time-consuming molecular screening methods while maintaining precise insertion detection
Data Source
AI summary
Methods and compositions are provided for driving expression of a coding sequence that has been integrated within the genome of a cell. A donor polynucleotide is integrated within the genome so that a non-functional promoter is located downstream of a genomic target sequence. This genomic target sequence can be bound by a site-specific promoter activation tool, wherein the site-specific promoter activation tool drives robust expression of a coding sequence that is operably linked to the non-functional promoter.