DNA Template Design for Precise mRNA Poly(A) Tail Length Control
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Solution Overview
Problem
Current methods for producing mRNA with polyadenylate tails face challenges in controlling tail length, leading to variability and complexity in purification, and require intricate DNA template construction that affects plasmid stability in E. coli.
Innovation Solution
A method involving PCR amplification and restriction enzyme cutting of DNA templates with integrated polyadenylate sequences, allowing for flexible adjustment of poly(A) tail length and integration with other DNA templates through ligation reactions, such as Gibson Assembly or overlap PCR, to produce mRNA with specific polyadenylate tail lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If poly(A) tail is added to DNA template using conventional methods, then mRNA with polyadenylate tail can be produced, but the tail length cannot be controlled precisely leading to variability
Solution Approach 1:
The patent incorporates the poly(A) tail sequence directly into the DNA template during the initial design phase. The DNA template is constructed with a predetermined poly(A) tail of specific length (e.g., 100-250 adenine residues) before transcription begins. This preliminary incorporation ensures that the poly(A) tail length is fixed and controllable from the start, eliminating the need for subsequent polyadenylation steps and ensuring consistent mRNA products with uniform tail lengths.
2Manufacturing precision
If poly(A) tail is added after transcription using poly(A) polymerase, then polyadenylate tail can be formed, but the tail length varies exceeding 100 bases making purification complex
Solution Approach 1:
The patent designs the DNA template to include the complete poly(A) tail sequence (100-250 adenine residues) as an integrated component before transcription. This preliminary incorporation ensures that the poly(A) tail length is predetermined and consistent across all mRNA molecules, eliminating the variability that occurs when poly(A) polymerase is used after transcription. The consistent tail length simplifies purification processes and maintains high-quality mRNA product.
3Adaptability or versatility
If DNA template is constructed on plasmid with long poly(A) structure, then poly(A) tail can be incorporated, but plasmid stability in E. coli is affected
Solution Approach 1:
The patent separates the poly(A) tail incorporation from the plasmid backbone structure. Instead of incorporating long poly(A) sequences directly into the plasmid vector, the method uses PCR amplification of the target gene with primers that include the poly(A) tail sequence. This segmentation allows the poly(A) tail to be added as a discrete element during amplification, avoiding the plasmid stability issues that arise from maintaining long poly(A) structures within the plasmid itself, while still achieving the desired polyadenylated mRNA product.
4Manufacturing precision
If DNA template with poly(A) tail is designed for each mRNA, then correct poly(A) tail length can be achieved, but the method becomes complex and time-consuming
Solution Approach 1:
The patent creates a universal PCR-based method that can generate DNA templates with various poly(A) tail lengths using the same basic protocol. By designing primers with appropriate poly(A) tail sequences and using PCR amplification, the same workflow can produce templates with different tail lengths (e.g., 100, 150, 200, 250 adenine residues) without requiring separate construction procedures for each mRNA application. This universal approach maintains precise control over poly(A) tail length while significantly reducing the time and complexity compared to designing custom templates for each mRNA.
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 approach simplifies the production of mRNA with consistent polyadenylate tail lengths, reducing production steps and costs, while maintaining high-quality mRNA consistency and reproducibility.
Implementation Method 1
using the first DNA template as a template, adding a forward primer and a reverse primer to perform PCR amplification of the first DNA template
Implementation Method 2
performing a cleavage on amplified the first DNA template using the first restriction enzyme, wherein the cleavage removes the specific sequence of the first DNA template to obtain the DNA template
Data Source
AI summary
The invention provides a method for producing a DNA template for mRNA containing a polyadenylate tail. This method is applicable to in vitro transcription reactions, generating mRNA with a specific polyadenylate tail length. Additionally, the invention further provides a method for extending the polyadenylate tail sequence using terminal deoxynucleotidyl transferase and combinations of restriction enzymes. This ensures that in in vitro transcription reactions, the mRNA can precisely terminate at the polyadenylate tail, thereby improving the accuracy and efficiency of mRNA synthesis.