CRISPR-Cas9 Double Nickase Design for Precise Genome Targeting
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Solution Overview
Problem
Current genome-editing techniques, such as designer zinc fingers and TALEs, are costly, complex, and not scalable for targeting multiple positions within eukaryotic genomes, necessitating a more affordable and efficient method for precise genome perturbation.
Innovation Solution
The CRISPR-Cas system is utilized with a guide sequence linked to a tracr mate sequence, which hybridizes to a tracr sequence, enabling precise genome editing through a CRISPR complex that includes Cas9 enzymes with improved target specificity, smaller size, and chimeric forms, along with methods to enhance activity and reduce toxicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional genome-editing techniques (designer zinc fingers, TALEs) are used, then precise genome targeting is achieved, but cost and complexity increase significantly
Solution Approach 1:
The patent uses RNA copies (guide RNA) to direct the Cas9 enzyme to specific genomic targets, replacing the need for complex protein-based targeting systems. The guide RNA contains a spacer sequence that is complementary to the target DNA, enabling precise targeting through RNA-DNA base pairing rather than complex protein-DNA interactions
Solution Approach 2:
The Cas9 enzyme serves as a universal tool that can be programmed to target any genomic location by simply changing the guide RNA sequence. This single enzyme system replaces multiple specialized proteins required by traditional methods, achieving both precision and simplicity
2Measurement precision
If traditional genome-editing techniques are used, then precise genome targeting is achieved, but scalability to multiple positions is limited
Solution Approach 1:
The CRISPR-Cas9 system enables simultaneous targeting of multiple genomic positions by introducing multiple guide RNAs, each with a different spacer sequence. This allows parallel editing at multiple loci without requiring separate protein complexes for each target, dramatically improving scalability while maintaining precision
3Productivity
If wild-type Cas9 is used, then genome editing capability is achieved, but off-target effects and toxicity increase
Solution Approach 1:
The patent introduces specific point mutations into the Cas9 enzyme at critical residues (D10A, N863A, H840A) to selectively abolish or reduce nuclease activity in specific contexts. These localized modifications allow the enzyme to maintain binding capability while reducing harmful cleavage activity at off-target sites
Solution Approach 2:
The patent converts the potentially harmful full nuclease activity of wild-type Cas9 into a beneficial nickase activity by mutating one catalytic domain. This reduces off-target double-strand breaks while maintaining on-target editing capability through controlled single-strand nicks that can be repaired with high fidelity
4Productivity
If full-length Cas9 is used, then genome editing function is complete, but enzyme size and delivery difficulty increase
Solution Approach 1:
The patent divides the Cas9 enzyme into functional domains and removes non-essential portions, creating a truncated version that retains core nuclease and RNA-binding functions. This segmented approach reduces enzyme size from approximately 1600 amino acids to a more manageable length while preserving essential genome editing capabilities
Solution Approach 2:
The patent extracts and removes specific domains or regions from the full-length Cas9 protein that are non-essential for core function. This extraction process creates a minimized Cas9 variant that is easier to deliver and express while maintaining sufficient activity for genome editing applications
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
This approach simplifies genome editing, enhances target specificity, and reduces off-target effects, facilitating applications in gene editing, therapy, drug discovery, and disease diagnosis.
Implementation Method 1
a guide sequence hybridized to a target sequence within the target polynucleotide
Implementation Method 2
the guide sequence is linked to a tracr mate sequence, which in turn hybridizes to a tracr sequence
Data Source
AI summary
The invention provides for delivery, engineering and optimization of systems, methods, and compositions for manipulation of sequences and/or activities of target sequences. Provided are vectors and vector systems, some of which encode one or more components of a CRISPR complex, as well as methods for the design and use of such vectors. Also provided are methods of directing CRISPR complex formation in prokaryotic and eukaryotic cells to ensure enhanced specificity for target recognition and avoidance of toxicity.