Cas12a Diversifying Base Editing for Targeted Plant Evolution
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Solution Overview
Problem
Current CRISPR-Cas systems, particularly Cas9-based base editors, are limited in their ability to induce a broad spectrum of mutations and are not suitable for directed evolution in organisms, and Cas12a systems are ineffective in plants, lacking functional dual base editing capabilities.
Innovation Solution
Development of Cas12a-based diversifying base editors with optimized architectures and guide RNAs to induce targeted point mutations, enabling a broader mutation spectrum and high editing efficiency, including C to G and A to T conversions, suitable for in situ directed evolution in plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If Cas9-based base editors are used for targeted point mutations, then editing precision is improved, but mutation spectrum diversity is limited
Solution Approach 1:
The patent combines multiple deaminase enzymes (APOBEC1, AID, A3A, A3B, PmCDA1) with Cas9 to create a diversified base editing system. This fusion protein integrates the DNA-targeting capability of Cas9 with the base conversion capabilities of multiple deaminases, enabling a broad mutation spectrum (C→T, C→G, A→T, A→G) while maintaining targeted editing precision at the desired locus.
Solution Approach 2:
The base editor system is designed to perform multiple base conversion functions simultaneously through the expression of multiple deaminase enzymes. The system can induce different types of point mutations (transitions and transversions) at the same target site, making it universally applicable for generating diverse mutations rather than being limited to a single mutation type.
2Adaptability or versatility
If random mutagenesis approaches (UV or EMS) are used to generate diversity, then mutation spectrum diversity is improved, but time consumption and labor intensity increase significantly
Solution Approach 1:
The patent replaces physical/chemical mutagenesis methods (UV irradiation, EMS treatment) with a molecular biology-based enzymatic system. Instead of using radiation or chemical agents to randomly induce mutations, the system uses engineered base editor proteins that chemically convert specific bases at targeted locations, achieving diversity generation through controlled biochemical reactions rather than physical/chemical stress.
Solution Approach 2:
The base editor system acts as an intermediary between the researcher's editing指令 and the genome. The deaminase enzymes serve as molecular mediators that translate the desired mutation into actual base conversions, enabling precise and controlled diversification without the need for time-consuming random mutagenesis screens.
3Manufacturing precision
If targeted CRISPR-Cas approaches are used for precise editing, then editing precision is improved, but directed evolution capability is lost
Solution Approach 1:
The base editor system introduces dynamic mutational capability into the targeted editing platform. Instead of static precise editing (wild-type to single specific mutation), the system dynamically generates multiple possible mutations at the target site through the action of multiple deaminase enzymes, enabling directed evolution by creating a library of variants from which useful mutations can be selected.
Solution Approach 2:
The system changes the parameter of mutation type diversity while maintaining the parameter of targeting precision. By expressing multiple deaminase enzymes with different specificities, the system expands the range of possible mutations (parameter change) that can be induced at a specific target location, thereby enabling directed evolution without sacrificing editing precision.
4Adaptability or versatility
If in vitro mutagenesis libraries are created for directed evolution, then directed evolution capability is improved, but phenotypic analysis becomes difficult
Solution Approach 1:
The base editor system performs the mutagenesis action directly within the living organism or cell, eliminating the need for separate in vitro library construction steps. The mutations are generated in situ during normal cellular processes, allowing immediate phenotypic analysis of the edited individuals without requiring complex in vitro library screening procedures.
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
Achieves targeted diversification with high efficiency, allowing for directed evolution and trait optimization in plants, including resistance to diseases and abiotic stresses, while minimizing off-target effects.
Implementation Method 1
CBEs catalyze the deamination of cytidines into uracil on the non-target DNA strand ultimately creating a C-G to T-A mutation
Data Source
AI summary
The present invention relates to the field of increasing genetic diversity in a targeted way. In particular, it relates to the provision of methods and means for targeted sequence diversification using base editors with an expanded mutation spectrum, including the provision of Cas12a diversifying base editing systems, and uses thereof.