Guide RNA Linker Constructs for Spacer Purity Analysis
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Solution Overview
Problem
Current CRISPR-Cas9 gene editing technologies face challenges in achieving high purity and safety due to truncated spacer sequences, which can lead to off-target effects and catastrophic risks, particularly with chemically modified RNAs longer than 160 nt, lacking reliable quality control methods.
Innovation Solution
Incorporation of a non-nucleotide linker in the spacer sequence of guide RNAs, combined with a DNA restriction enzyme cleavage site, to produce a short RNA fragment for precise analysis and purification, ensuring high purity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If chemically modified RNAs longer than 160 nt are used in prime editing, then the versatility and applicability of gene editing is improved, but the manufacturing precision and quality control become significantly more challenging
Solution Approach 1:
The guide RNA is divided into multiple segments that are chemically ligated together, with non-nucleotide linkers placed at specific positions to create identifiable fragmentation patterns. This segmentation enables precise quality control through restriction enzyme cleavage and HPLC analysis, while still achieving the required length for prime editing applications.
Solution Approach 2:
Non-nucleotide linkers are introduced as intermediary elements within the guide RNA structure. These linkers serve dual purposes: they maintain the structural integrity and function of the long guide RNA, while simultaneously creating specific cleavage sites that enable precise quality control and purity assessment through restriction enzyme digestion.
2Productivity
If guide RNA production is scaled up to kilogram levels, then the productivity is improved, but the measurement precision of spacer purity becomes insufficient
Solution Approach 1:
Non-nucleotide linkers are incorporated into the guide RNA structure during synthesis to create predetermined cleavage sites. This preliminary action enables subsequent precise measurement of spacer purity through restriction enzyme digestion and HPLC analysis, even at kilogram production scales where direct measurement becomes impractical.
Solution Approach 2:
The patent replaces direct physical measurement of spacer purity with an indirect biochemical assay system. Restriction enzymes are used to cleave the guide RNA at specific non-nucleotide linker sites, and the resulting fragments are analyzed by HPLC to determine spacer purity, enabling precise measurement at scale.
3Ease of manufacture
If truncated spacer sequences are not minimized, then the ease of manufacture is improved, but the reliability and safety of gene editing deteriorate due to off-target effects
Solution Approach 1:
The patent converts the potential harm of truncated spacer sequences into a beneficial quality control mechanism. Non-nucleotide linkers are strategically placed to create specific fragmentation patterns that enable detection and quantification of truncated spacers through HPLC analysis, transforming a manufacturing challenge into a precise quality assurance tool.
Solution Approach 2:
The restriction enzyme cleavage and HPLC analysis system provides feedback on the purity of guide RNA products. By measuring the ratio of full-length to truncated spacer sequences, manufacturers can adjust production parameters to minimize truncated spacers while maintaining ease of manufacture at scale.
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 solution enables robust GMP production and quality control, minimizing truncated spacer impurities and reducing off-target risks, thereby enhancing the safety and efficacy of therapeutic gene editing.
Implementation Method 1
constructs of guide RNAs incorporated with a cleavage site of a DNA restriction enzyme close to the internal end of the spacer of a guide RNA, which provides a short guide RNA fragment for accurate analysis of its spacer purity after restriction DNA cleavage
Data Source
AI summary
This invention provides guide RNA (gRNA) constructs designed to enhance safety and precision in therapeutic gene editing across RNA-guided systems. The constructs incorporate a non-nucleotide linker near the middle of the spacer sequence, reducing truncated spacer impurities (e.g., n−1 variants) during production by ligating short RNA segments (e.g., 10 nt and 22 nt)—minimizing off-target risks in gene editing therapies. Additionally, a DNA restriction enzyme cleavage site near the spacer's internal end enables excision of a short RNA fragment (e.g., 32 nt for spCas9) for precise spacer purity analysis via LC-MS or electrophoresis. These features ensure robust GMP production and quality control, overcoming limitations of conventional gRNAs and long RNAs (>160 nt) used in diverse editing platforms. Applicable to CRISPR-based and other RNA-guided methods, the constructs maintain or enhance activity, offering a scalable, safe solution for therapeutic gene editing.