Host Cell Genome Integration of Large DNA Fragments
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Solution Overview
Problem
Current methods for recombinant expression of large DNA fragments in host cells face challenges such as genetic instability, requirement for antibiotic selection, and limitations in inserting DNA fragments larger than 8 kb at desired sites in host cell genomes, making it difficult to combine multiple large DNA fragments and maintain stability during protein production.
Innovation Solution
A method involving a donor plasmid with a heterologous insert DNA of at least 8 kb flanked by homology regions and a helper plasmid encoding lambda red recombinase and a restriction endonuclease, allowing for site-specific integration of large DNA sequences into host cell genomes without the need for antibiotic selection, enabling stable expression of proteins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If standard expression plasmids are used for recombinant expression, then protein production is achieved, but genetic stability is poor following insertion of large DNA fragments
Solution Approach 1:
The patent introduces a site-specific integration system using a specific genomic location (attP site) as an intermediary for inserting large DNA fragments. This mediator enables stable integration without relying on plasmid maintenance, thereby achieving both high productivity and genetic stability for large DNA fragment expression.
2Ease of manufacture
If plasmids are used for DNA insertion, then recombinant expression is achieved, but antibiotic selection is required which causes allergic reactions and additional costs
Solution Approach 1:
The patent extracts and eliminates the antibiotic selection requirement from the recombinant expression system. By using site-specific chromosomal integration, the system achieves stable maintenance of large DNA fragments without needing antibiotic pressure, thereby removing the harmful factor of antibiotic exposure while maintaining ease of manufacture.
3Stability of the object's composition
If cosmids and fosmids are used to stabilize large DNA fragments, then genetic stability is improved, but the number of available vectors is limited and combining multiple large fragments becomes difficult
Solution Approach 1:
The patent creates a universal site-specific integration system that can accommodate multiple large DNA fragments at defined genomic locations. The attP site and associated integration machinery provide a multi-functional platform that enables both stable maintenance and flexible combination of multiple large fragments, overcoming the limitations of cosmids and fosmids.
4Length of stationary object
If existing chromosomal insertion methods are used, then some DNA insertion is achieved, but insertion of fragments larger than 8 kb at desired sites is not possible
Solution Approach 1:
The patent prepares the host cell genome in advance by defining specific integration sites (attP locations) and equipping them with the necessary recognition elements. This preliminary preparation enables the precise insertion of large DNA fragments (>8 kb) at desired genomic locations, achieving both increased fragment size capability and manufacturing precision.
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
This method allows for the stable integration and expression of large DNA sequences in host cells, eliminating the need for antibiotic selection and ensuring genetic stability, facilitating the production of proteins like vaccines and glycosylated proteins without the risks associated with antibiotic use.
Implementation Method 1
a helper plasmid comprising under control of a first promoter, an open reading frame encoding lambda red recombinase
Implementation Method 2
an open reading frame encoding a restriction endonuclease that has a recognition sequence that is not present in the host cell genome
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Described herein are novel methods of inserting nucleic acid sequences into host cells. Also described herein are genetically stable host cells comprising inserted nucleic acid sequences and methods of using such host cells in the generation of proteins.