Capped Oligonucleotide Primers for Homogeneous 5'-Capped RNA Synthesis
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Solution Overview
Problem
Current methods for synthesizing 5'-capped RNAs are laborious, inefficient, costly, and result in low yields with significant production of heterogeneous products, requiring additional enzymatic steps for Cap 1 and Cap 2 structures, and are difficult to control, especially in large-scale manufacturing.
Innovation Solution
A complex comprising an initiating capped oligonucleotide primer with a specific structure and a polynucleotide template is used, allowing for co-transcriptional synthesis of 5'-capped RNAs, reducing bi-directional initiation and eliminating the need for additional enzymatic reactions to incorporate Cap 1 and Cap 2 structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional enzymatic capping methods are used to synthesize 5'-capped RNAs, then the Cap structure can be introduced, but the process becomes laborious, inefficient, and costly with low yields
Solution Approach 1:
The Cap structure is pre-installed on the initiating oligonucleotide primer before transcription begins. This preliminary action eliminates the need for subsequent enzymatic capping steps, directly resolving the contradiction by improving synthesis efficiency while reducing process complexity.
Solution Approach 2:
The capping step is extracted and removed from the transcription process. By using a pre-capped primer, the complex enzymatic capping procedure is completely eliminated, leaving only the essential transcription step, thus improving efficiency and simplifying the process.
2Reliability
If additional enzymatic steps are performed to incorporate Cap 1 and Cap 2 structures, then translation efficacy and nuclease stability are improved, but the process becomes more laborious and difficult to control
Solution Approach 1:
The 2'-O-methylation modification is pre-installed on the primer nucleotides before transcription. This preliminary action ensures high translation efficacy and nuclease stability while avoiding the need for additional enzymatic methylation steps, thereby maintaining ease of operation and control.
Solution Approach 2:
The enzymatic methylation steps are extracted and removed from the process. By using pre-modified primers with Cap 1 and/or Cap 2 structures, the complex multi-step enzymatic process is replaced with a single transcription step, improving both reliability and ease of control.
3Productivity
If large-scale synthesis is performed using conventional methods, then production capacity increases, but the process becomes difficult to control and yields heterogeneous products
Solution Approach 1:
The Cap structure and modifications are pre-installed on the primer before large-scale transcription. This ensures that every RNA molecule produced inherits the correct structure from the beginning, maintaining high product homogeneity even at large production scales.
Solution Approach 2:
The synthesis process is segmented into two independent stages: (1) preparation of pre-capped and pre-modified primers, and (2) large-scale transcription. This segmentation allows optimization of each stage independently, ensuring product homogeneity while achieving high production capacity.
4Manufacturing precision
If bi-directional initiation is reduced by using symmetric mCAP analogs, then product homogeneity improves, but the cost increases due to large molar excess required
Solution Approach 1:
The Cap structure is pre-installed on the initiating primer with defined sequence and structure. This eliminates the need for symmetric mCAP analogs and large molar excesses, achieving both product homogeneity and reduced reagent consumption.
Solution Approach 2:
Instead of using symmetric mCAP analogs, the invention employs an asymmetric pre-capped oligonucleotide primer with a specific sequence (e.g., 5'-Cap-pGpG or 5'-Cap-pGpU). This asymmetric design provides directional initiation with high homogeneity while eliminating the need for large reagent excess.
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 achieves higher yields of 5'-capped RNAs with reduced costs and labor, minimizing heterogeneous products, and allows for the synthesis of RNAs with modified nucleosides and affinity tags, suitable for various biological and therapeutic applications.
Implementation Method 1
transcription by the RNA polymerase of the polynucleotide template
Implementation Method 2
B1 in the initiating capped oligonucleotide primer is complementary to the first nucleoside base and B2 is complementary to the second nucleoside base
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A complex comprises an initiating capped oligonucleotide primer and a polynucleotide template, the initiating capped oligonucleotide primer comprising the following structure: wherein: B1 is adenine, B2 is guanine, R1 is OH, R2 is OH, and R3 is O-methyl, wherein the polynucleotide template comprises a first nucleoside base at transcription template position +1 and a second nucleoside base at transcription template position +2, and wherein B1 is complementary to the first nucleoside base and B2 is complementary to the second nucleoside base. In a primer per se, B1 is N6-methyladenine, and methods of synthesizing RNA use a primer in which B1 is adenine or N6-methyladenine.