SECURE Base Editor Variants for Reduced Off-Target RNA Editing
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Solution Overview
Problem
Existing cytosine base editors (CBEs) exhibit significant RNA editing activity alongside their intended DNA editing, leading to unwanted RNA mutations, which can disrupt cellular function.
Innovation Solution
Development of cytosine deaminase variants, such as APOBEC1 with specific mutations at residues like P29, R33, K34, E181, and L182, combined with a programmable DNA binding domain, to reduce RNA editing activity while maintaining DNA editing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type APOBEC1 is used in base editors, then DNA editing activity is achieved, but unwanted RNA editing activity occurs
Solution Approach 1:
The patent applies parameter changes by introducing specific amino acid mutations at positions P29, R33, K34, E181, and L182 of the APOBEC1 protein. These mutations alter the biochemical parameters of the enzyme to reduce its affinity for RNA substrates while preserving its DNA editing capability, thereby eliminating harmful off-target RNA mutations
Solution Approach 2:
The patent applies local quality by making site-specific mutations only at particular amino acid residues (P29, R33, K34, E181, L182) rather than throughout the entire protein. This localized modification approach selectively reduces RNA editing activity in specific regions of the enzyme while maintaining overall DNA editing function
2Object-generated harmful factors
If mutations are introduced to reduce RNA editing activity, then RNA editing is curtailed, but DNA editing efficiency may be compromised
Solution Approach 1:
The patent systematically tests multiple mutation combinations (P29F/P29T, R33A, K34A, E181Q, L182A) to identify parameter changes that specifically reduce RNA editing activity while preserving DNA editing efficiency. The optimized variants achieve this selective parameter modification
Solution Approach 2:
The patent employs feedback through iterative testing and characterization of mutant variants. By measuring both RNA editing reduction and DNA editing efficiency for each mutant combination, the researchers can refine and optimize the mutations to achieve the desired balance between curbing harmful RNA editing and maintaining productive DNA editing
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 engineered base editors effectively curb unwanted RNA editing, preserving DNA editing capabilities and minimizing off-target RNA mutations, thus enhancing the specificity and safety of genetic editing.
Implementation Method 1
cytosine base editors that induce targeted cytosine (C) to uracil (U) alterations in single-stranded DNA by using catalytically inactive or nickase versions of CRISPR-Cas nucleases to direct Apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) cytosine deaminases to cytosines
Data Source
AI summary
Engineered base editor variants with reduced RNA editing activity, and methods of using the same.