RNA-Guided Tn7 Transposon Integration Without DNA Breaks
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Solution Overview
Problem
Current CRISPR-Cas9 systems for gene integration in eukaryotic genomes face challenges such as off-target mutations, DNA damage, low homology-directed repair efficiency, and inability to integrate in non-dividing cells, leading to inefficient and hazardous gene integration.
Innovation Solution
An RNA-guided DNA integration method using an engineered CRISPR-Cas system derived from Type I CRISPR-Cas and a Tn7-like transposon system, which integrates donor DNA proximal to a target site without introducing double-strand breaks, utilizing TnsA, TnsB, TnsC, and TnsD/TniQ components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CRISPR-Cas9 is used for gene integration, then gene integration capability is achieved, but off-target mutations and DNA damage occur
Solution Approach 1:
The patent introduces a Tn7-like transposon system as an intermediary mechanism between the CRISPR-Cas9 targeting system and the final gene integration. The transposon system (comprising TnsA, TnsB, TnsC, and TnsD/TniQ components) acts as a mediator that receives the target site information from CRISPR-Cas9 binding and executes the integration without requiring DSB formation, thereby eliminating off-target mutations and DNA damage while maintaining precise gene integration capability
Solution Approach 2:
The patent replaces the mechanical DSB-based integration mechanism of CRISPR-Cas9 with a biochemical transposon-based integration mechanism. Instead of using nucleolytic cleavage and cellular repair pathways (mechanical system), the invention uses transposase enzymes to catalyze direct DNA insertion (biochemical system), which achieves the same gene integration function without the harmful side effects of DSB formation
2Manufacturing precision
If CRISPR-Cas9 with HDR is used for gene integration, then site-specific integration is achieved, but HDR efficiency is extremely low in many cell types
Solution Approach 1:
The patent employs a copy-and-paste transposition mechanism where the transposon system copies the donor DNA sequence and inserts it at the CRISPR-Cas9 targeted site. This copying mechanism bypasses the inefficient HDR pathway entirely, achieving high-efficiency site-specific integration in both dividing and non-dividing cells without relying on homology-directed repair
Solution Approach 2:
The patent changes the fundamental parameter of the integration mechanism from HDR-dependent (low efficiency in many cell types) to transposon-dependent (high efficiency across all cell types). By altering the molecular mechanism from homology-based repair to transposase-catalyzed insertion, the system achieves consistent high-efficiency integration regardless of cell division status or HDR capacity
3Productivity
If CRISPR-Cas9 is used for gene integration, then gene integration is achieved, but it cannot integrate in non-dividing cells
Solution Approach 1:
The patent segments the integration function into two independent modules: (1) CRISPR-Cas9 for target site recognition and binding, and (2) Tn7-like transposon system for actual DNA insertion. This segmentation allows the transposon module to operate independently of cell division cycles, enabling gene integration in non-dividing cells while maintaining precise targeting through the CRISPR module
Solution Approach 2:
The patent creates a universal integration system that functions across all cell types (dividing and non-dividing) by combining the targeting versatility of CRISPR-Cas9 with the division-independent insertion capability of Tn7-like transposons. The transposon system's ability to catalyze DNA insertion without requiring cellular replication machinery makes the overall system universally applicable to all eukaryotic cells regardless of their proliferative state
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
Enables precise and efficient gene integration in various cell types, including non-dividing cells, reducing DNA damage risks and improving integration efficiency compared to traditional CRISPR-Cas9 methods.
Implementation Method 1
The CRISPR/Cas9 system exploits RNA-guided DNA-binding and sequence-specific cleavage of a target DNA. A guide RNA (gRNA) is complementary to a target DNA sequence upstream of a PAM (protospacer adjacent motif) site.
Implementation Method 2
an engineered transposon system derived from a Tn7-like transposon system, where the engineered transposon system comprises TnsA, TnsB, TnsC and TnsD/TniQ
Data Source
AI summary
In certain embodiments, the present systems and methods use Tn7-like transposons that encode CRISPR-Cas systems for programmable, RNA-guided DNA integration. For example, the CRISPR-Cas machinery directs the Tn7 transposon-associated proteins to integrate DNA downstream of a target site (e.g., a genomic target site) recognized by a guide RNA (gRNA).