Modular HDR Donor Plasmids for Rapid Cell Line Development
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Solution Overview
Problem
The existing methods for generating homologous recombination vectors and selecting pure cell clones are laborious, time-consuming, and require expensive equipment, making them inaccessible to many laboratories.
Innovation Solution
The development of a novel HDR donor vector system that allows for the rapid construction of vectors with multiple tags and selection markers, utilizing a backbone plasmid with dual expression cassettes for toxic proteins to ensure accurate cloning of recombination arms, enabling quick selection of modified cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional multi-step cloning methods are used to construct donor plasmids, then cloning accuracy can be maintained, but the construction process becomes laborious and time-consuming
Solution Approach 1:
The donor plasmid is divided into modular components: a backbone plasmid containing dual expression cassettes for negative selection markers, and separate recombination arms that can be independently designed and assembled. This segmentation allows parallel construction of different components and simplifies the overall cloning process.
Solution Approach 2:
The backbone plasmid is pre-prepared with dual expression cassettes containing negative selection markers (such as ccdB) positioned at the multiple cloning site. This preliminary setup eliminates the need to construct negative selection marker cassettes during each cloning experiment, significantly reducing construction time and complexity.
2Productivity
If conventional cell selection methods using resistance cassettes are employed, then pure cell clones can be obtained, but the selection process requires expensive equipment and takes multiple weeks
Solution Approach 1:
The patent utilizes toxic proteins (negative selection markers) that kill non-modified cells as a beneficial selection mechanism. By placing these toxic markers under the control of constitutive promoters in the backbone plasmid, only cells that successfully integrate the recombination arms (and thus lose the toxic markers through homologous recombination) survive. This converts a potentially harmful toxic element into a useful selection tool that works with standard laboratory equipment.
Solution Approach 2:
The selection system is designed to be self-selecting through the use of negative selection markers. The dual expression cassettes automatically provide toxic proteins that eliminate non-modified cells without requiring external intervention or expensive sorting equipment. The system performs its own selection function through the inherent toxicity of the marker proteins.
3Adaptability or versatility
If donor plasmids with multiple tags and cassettes are constructed using traditional methods, then functional versatility is achieved, but the construction time increases significantly
Solution Approach 1:
The backbone plasmid is designed as a universal platform that can accommodate various recombination arms with different tags and functional elements. The dual expression cassettes with negative selection markers serve multiple purposes: they enable selection, facilitate cloning verification, and work with any recombination arm design. This universal backbone can be reused for constructing different donor plasmids by simply changing the recombination arms.
Data Source
AI summary
The present invention provides homologous recombination vectors to insert transgenic DNA in cells. These vectors shorten the production time and allow for easy generation of genetically modified cells. The invention allows the user to test multiple tags and to generate homozygous modified cell line using the homologous recombination vector. The invention can be used to generate knockout cells, to generate cell lines with knockin genes, to generate cell lines for drug screening against any target, to create transgenic animals, or in gene therapy.