Chimeric Polypeptides for Site-Specific Genome Recombination
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Solution Overview
Problem
Current methods for targeted and site-specific recombination in genomes face challenges due to strict sequence requirements, off-target cleavage events, and limited modularity, hindering applications in gene therapy and biotechnology.
Innovation Solution
Development of chimeric polypeptides comprising a recombinase or nuclease fused with a transcription activator-like effector (TALE) protein, and zinc finger binding domains, which can be customized to recognize specific DNA sequences, allowing for site-specific integration and recombination without activating the cellular DNA damage response pathway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zinc-finger nucleases are used for targeted genome editing, then sequence-specific DNA recognition is achieved, but off-target cleavage events occur and detection is difficult
Solution Approach 1:
The nuclease domain is divided into two separate components: a TALE DNA-binding domain that provides sequence-specific recognition, and a nuclease domain that performs the cleavage function. This segmentation allows independent optimization of binding specificity and cleavage activity, reducing off-target effects while maintaining targeted precision.
Solution Approach 2:
The TALE protein acts as an intermediary between the nuclease domain and the target DNA. It binds specifically to the intended target sequence through its repeat structure, serving as a mediator that guides the nuclease to the correct location while preventing off-target cleavage events.
2Measurement precision
If site-specific recombinases are used for targeted recombination, then target site specificity is achieved, but strict sequence requirements limit adaptability
Solution Approach 1:
The TALE DNA-binding domain is designed with universal applicability through its modular repeat structure. Each repeat can be configured to recognize different DNA sequences, allowing a single TALE-based platform to target multiple specific locations in the genome without requiring different fundamental protein architectures.
Solution Approach 2:
The TALE repeat array provides dynamic adaptability through variable di-residue configurations. By changing the amino acid sequence at specific positions within the repeats, the protein can dynamically adjust its DNA recognition specificity to match different target sequences while maintaining the overall structural framework.
3Productivity
If chimeric nucleases are used for genome engineering, then targeted DNA cleavage is achieved, but cellular DNA damage response pathway is activated
Solution Approach 1:
The DNA-binding function is extracted from the nuclease domain and placed into a separate TALE protein. This extraction allows the nuclease to perform its cleavage function only after specific DNA binding has occurred, enabling controlled activation that reduces unwanted cellular DNA damage responses while maintaining targeted cleavage efficiency.
4Ease of manufacture
If TALE proteins are used for DNA binding, then modularity and ease of design are improved, but construction of high-affinity ZFPs remains difficult
Solution Approach 1:
The TALE protein utilizes changes in amino acid parameters (specifically the variable di-residues at positions 12-13 of each repeat) to achieve different DNA binding specificities. This parameter-based approach simplifies the design process compared to traditional zinc-finger construction, as only specific amino acid changes are needed to target different sequences while maintaining modular architecture.
Data Source
AI summary
Disclosed herein are chimeric polypeptides, including compositions thereof, expression vectors, and methods of use thereof, for the generation of transgenic cells, tissues, plants, and animals. The compositions, vectors, and methods of the present invention are also useful in gene therapy techniques.