Antibiotic-Free Plasmid Production Using Toxin-Antitoxin RNA Control
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Solution Overview
Problem
Existing plasmid systems for gene therapy carry antibiotic marker genes and prokaryotic bacterial backbones, leading to side effects, antibiotic resistance, and decreased transfection efficiency, while requiring costly and uncontrollable auxiliary inhibitors.
Innovation Solution
A resistance-free plasmid production system using a toxin-antitoxin system, where a toxic gene and an anti-toxic gene are regulated by an operon, and a small RNA inhibitor, eliminating the need for antibiotics and reducing the prokaryotic backbone, thereby increasing plasmid yield and reducing production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If antibiotics are used during plasmid production, then plasmid yield and purity are improved, but antibiotic resistance development and environmental pollution worsen
Solution Approach 1:
The patent removes antibiotics from the plasmid production process entirely. Instead of using antibiotic selection markers during plasmid isolation, the invention employs alternative methods such as chromosomal DNA removal through enzymatic treatment and purification steps that selectively isolate plasmid DNA without requiring antibiotic presence, thereby eliminating the harmful effects while maintaining product quality
Solution Approach 2:
The patent introduces intermediary substances and methods to replace the function of antibiotics. This includes using specific enzymes (such as nucleases) as intermediaries to selectively degrade contaminating chromosomal DNA, and employing intermediary purification steps (such as differential lysis or selective precipitation) that mediate between the crude extract and final pure plasmid product, achieving purification without antibiotics
2Quantity of substance
If conventional plasmid isolation methods are used, then plasmid production is achieved, but chromosomal DNA contamination and low purity result
Solution Approach 1:
The patent divides the plasmid isolation process into distinct sequential stages: (1) cell lysis to release DNA, (2) chromosomal DNA fragmentation and removal, (3) plasmid DNA purification, and (4) final concentration. Each stage targets specific contaminants while preserving plasmid integrity, with intermediate purification steps that progressively enhance purity while maintaining adequate yield
Solution Approach 2:
The patent applies different treatment conditions to different components of the DNA mixture. Specific enzymes or purification reagents are used that selectively act on chromosomal DNA or proteins while leaving plasmid DNA unaffected. For example, controlled nuclease treatment degrades linear chromosomal DNA while circular plasmid DNA remains intact, or selective precipitation conditions that pellet contaminants while keeping plasmid in solution
3Manufacturing precision
If multiple purification steps are added to remove chromosomal DNA, then plasmid purity is improved, but process complexity and time increase
Solution Approach 1:
The patent combines multiple purification functions into integrated steps. For example, a single purification buffer system simultaneously performs salt precipitation of proteins, neutralization of lysis conditions, and protection of plasmid DNA. Enzymatic treatment steps are designed to perform multiple functions (chromosomal DNA degradation, protein denaturation, and contaminant removal) in one operation, reducing the total number of separate purification stages required
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 system achieves a 4-5 times higher plasmid copy number, improves safety, and significantly reduces production costs by eliminating antibiotics and auxiliary inhibitors, enhancing transfection efficiency.
Implementation Method 1
F1 infestation control agents are introduced into the fermentation system to control F2 pests
Implementation Method 2
fermentation system comprising a fermentation reactor and a fermentation control unit
Data Source
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AI summary
The present invention relates to a resistance-free plasmid production system. The present invention combines toxic transcripts/anti-toxic transcripts, operon-related elements and small RNAs to construct a plasmid comprising a nucleic acid fragment 3 encoding a small RNA, and host cell expression cassettes comprising a toxic gene expression cassette and an anti-toxic gene expression cassette, wherein the toxic gene expression cassette comprises a promoter and a nucleic acid fragment 1 for transcribing the toxic transcript, and the anti-toxic gene expression cassette comprises a promoter, an operon and a nucleic acid fragment 2 for transcribing the anti-toxic transcript. The reverse complementation of the nucleic acid fragment 3 and the nucleic acid fragment 1 produces a steric effect to inhibit the function of the toxic transcript, so that the entire plasmid production process does not need to be added with antibiotics or other inhibitors to realize the screening and production of the plasmid, thereby the harm of antibiotics and inhibitors to the plasmid in cell gene therapy is solved.