Expression Vector With IRES And Glutamine Synthetase Selection
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Solution Overview
Problem
Current expression vectors for recombinant protein production in mammalian cells exhibit variable expression levels and require cumbersome selection processes, leading to inefficiencies and increased production costs.
Innovation Solution
An expression vector is designed with a gene expression regulatory site, a protein of interest gene, an internal ribosome entry site, and a glutamine synthetase gene, allowing for high-level expression and selection of mammalian cells using methionine sulfoximine and puromycin resistance, thereby optimizing protein production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional expression vectors with drug resistance markers are used for selection, then cell selection is achieved, but expression levels vary and selection process becomes cumbersome
Solution Approach 1:
The patent changes the selection mechanism from drug resistance-based to metabolic dependency-based. By using a conditional essential gene whose expression is controlled by a regulatable promoter (inducible or repressible), the invention creates a parameter change in the selection criterion: cells must maintain appropriate levels of the conditional essential gene product to survive, which directly correlates with high-level expression of the protein of interest. This eliminates the need for separate drug resistance markers and streamlines the selection process.
Solution Approach 2:
The regulatable promoter serves multiple functions: it drives expression of the conditional essential gene for selection purposes, and its regulability allows control over expression levels of both the selection marker and the protein of interest. This multi-functional design consolidates selection and expression control into a single regulatory element, reducing system complexity while improving reliability of expression level consistency.
2Productivity
If multiple selection markers are incorporated to ensure high expression levels, then selection efficiency improves, but vector structure becomes more complex
Solution Approach 1:
The patent extracts the selection function from separate drug resistance marker genes and integrates it into the essential gene system. By removing the need for multiple independent selection markers and consolidating the selection mechanism into a single conditional essential gene under regulatable promoter control, the invention simplifies vector structure while maintaining or improving selection efficiency. The essential gene itself becomes the selection marker through conditional essentiality.
3Reliability
If drug resistance markers are used for cell selection, then viable cells can be obtained, but production costs increase
Solution Approach 1:
The patent employs a selection system based on metabolic essentiality rather than drug resistance. The conditional essential gene approach uses naturally occurring metabolic dependencies of mammalian cells, eliminating the need for expensive drug resistance markers and associated selection antibiotics. This reduces manufacturing costs while maintaining reliable cell viability through the essential metabolic function provided by the conditional essential gene.
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 configuration enables efficient and cost-effective production of recombinant proteins by selecting cells with high expression levels, reducing production costs and improving yield.
Implementation Method 1
an internal ribosome entry site further downstream thereof
Implementation Method 2
Glutamine synthetase is an enzyme which synthesizes glutamine from glutamic acid and ammonia
Data Source
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AI summary
Disclosed are a novel expression vector for efficient expression of recombinant proteins in mammalian cells, a mammalian cell transformed with the vector, and a method for production of the mammalian cell. The expression vector includes a gene expression regulatory site, and a gene encoding the protein downstream thereof, and an internal ribosome entry site further downstream thereof, and a gene encoding a glutamine synthetase further downstream thereof.