In the rapidly evolving field of biotechnology, the production of messenger RNA (mRNA) has become a critical process, particularly for the development of vaccines and therapeutic agents. A core step in this production process is In Vitro Transcription (IVT), which serves as a foundation for generating high-quality mRNA. 

This blog explores the intricate details of the IVT process, focusing on how it can enhance output, reduce material consumption and production costs, and ensure the integrity and performance of the resulting mRNA. We will also delve into the role of T7 RNA Polymerase (RNAP) in the IVT system and examine how different buffer components affect the efficiency and quality of the transcription process.

How T7 RNA Polymerase Affect IVT System
In the IVT system, compared with other RNA polymerases, T7 RNAP has the characteristics of highly specific recognition of T7 promoter sequence and can complete transcription without additional proteins or cofactors, which makes T7 RNAP the best choice for in vitro transcriptional production of mRNA.

By combining fluorescence signal-based fluorescence activated droplets sorting (FADS) with the enzyme directed evolution platform, HZYMES screened out a variety of T7 RNA polymerase mutants, including heat-resistant, high-specific activity and low-dsRNA mutants.

FADS technology is the mainstream microfluidic screening technology at present. By designing different fluorescent probes or enzyme cascade reactions, the target enzyme genotype and fluorescence can be directly or indirectly coupled, and the sorting flux of microdrops can be as high as 5000/s. At the same time, the visualization of sorting can be realized through the configured high-speed camera [3].

The Importance of In Vitro Transcription in mRNA Production
Enhancing Output and Reducing Costs
In Vitro Transcription is a pivotal technique used to synthesize mRNA from a DNA template. A thorough and optimized IVT system can significantly enhance the yield of mRNA, which is essential for both research and commercial production. By fine-tuning the IVT conditions, researchers can maximize the efficiency of the transcription process, thereby increasing the output while minimizing the consumption of raw materials. This optimization not only reduces production costs but also ensures that the mRNA produced meets stringent quality standards.

Ensuring Molecular Integrity and Quality
The quality of mRNA is critical for its performance in various applications. Key quality indicators include molecular integrity, capping efficiency, and the absence of double-stranded RNA (dsRNA) impurities. A well-optimized IVT system can address these quality concerns, ensuring that the mRNA molecules are intact, properly capped, and free from contaminants. This, in turn, reduces the complexity and cost of downstream purification processes, making the overall production more efficient and reliable.

The Role of T7 RNA Polymerase in IVT Systems
Why T7 RNA Polymerase?
T7 RNA Polymerase (RNAP) is the enzyme of choice for many IVT systems due to its unique properties. Unlike other RNA polymerases, T7 RNAP has a highly specific recognition of the T7 promoter sequence and can complete transcription without the need for additional proteins or cofactors. This specificity and independence make T7 RNAP particularly suitable for in vitro transcription, as it ensures a high-fidelity transcription process and robust mRNA yields.

Advances in T7 RNAP: HZYMES’ Innovations

Using the above platform, HZYMES carried out directional evolution of the high temperature resistance of T7 RNAP by gradually increasing the temperature screening pressure, and finally obtained the target mutant M16 (item number: HBP000350), which increased the half-life at 52℃ by 270 times and the catalytic activity by 58 times.


HZYMES  has made significant advancements in the field of T7 RNAP through the application of Fluorescence Activated Droplets Sorting (FADS) combined with enzyme-directed evolution. This innovative approach has led to the development of various T7 RNAP mutants with enhanced properties such as heat resistance, high specific activity, and reduced dsRNA production.

Heat-Resistant Mutant M16
One of the notable achievements is the heat-resistant T7 RNAP mutant M16 (item number: HBP000350). By gradually increasing the temperature screening pressure during the evolutionary process, HZYMES obtained this mutant, which demonstrated a remarkable 270-fold increase in half-life at 52℃ and a 58-fold increase in catalytic activity compared to the wild-type enzyme.

High-Activity Mutant M6
Another significant development is the high-activity T7 RNAP mutant M6 (item number: HBP000330). This mutant exhibited superior performance in terms of specific activity, transcription yield, and product integrity, making it an excellent choice for IVT applications.

The Impact of Buffer Components on IVT Systems
The Importance of Reaction Buffers
 
How Buffer affect IVT System
Having high-performance enzymes is key, but simply having high-performance enzymes is not enough. In order to maximize the performance of the enzyme and adapt to different templates, the optimization of the reaction buffer is also crucial.
Rosa et al. optimized IVT response with 12 different parameters by Bayesian optimization method to effectively increase mRNA yield [6]. Among them, pH and magnesium ions have the most significant influence on IVT reaction.


• pH value and buffer
The choice of appropriate buffer and pH also affects the quality of the final IVT product.

• Mg2+ concentration
Suitable magnesium ion concentration can promote polymerase activity, but too high concentration may lead to non-specific binding and by-product formation.


• other additives

Advanced Monitoring Techniques: HZYMES’ STAR Method
HZYMES has developed a real-time in vitro transcriptional activity monitoring method known as STAR (patent No. CN115896213A). This method utilizes the iSpinach aptamer to provide real-time feedback on the transcription process, allowing for immediate adjustments and optimization.

Comprehensive Services by HZYMES
HZYMES offers a complete suite of services and products related to mRNA production, including:

– High-Performance Enzyme Raw Materials: Enzymes tailored for IVT applications.
– Biochemical Substrates: Essential components for the transcription process.
– IVT Kits: Comprehensive kits for mRNA synthesis.
– Quality Control Kits: Tools for ensuring the integrity and performance of mRNA products.
– Process Development Services: Custom development of IVT processes to meet specific needs.
– mRNA Purification and LNP Encapsulation: Advanced techniques for purifying mRNA and encapsulating it in lipid nanoparticles for delivery.
– Third-Party Quality Inspection: Independent verification of mRNA quality.
– Finished mRNA Stock Products: Ready-to-use mRNA products coding for various proteins, including reporter genes, target proteins, gene editing proteins, and antigen proteins.

Supporting Drug Development
HZYMES’ comprehensive offerings are designed to support customers at all stages of drug development, from early-stage research to commercial production. They provide Contract Research Organization (CRO) services, proof of concept services, and a range of finished mRNA products, helping customers to quickly advance their research and development projects.

Conclusion
In Vitro Transcription (IVT) is a cornerstone of mRNA production, and optimizing this process is essential for producing high-quality mRNA efficiently and cost-effectively. T7 RNA Polymerase plays a critical role in IVT systems due to its specificity and independence, and advances in enzyme engineering have further enhanced its performance. Additionally, the optimization of buffer components is crucial for maximizing enzyme activity and ensuring the integrity of the final product. With cutting-edge technologies and comprehensive services, HZYMES is at the forefront of mRNA production, supporting the development of innovative therapies and vaccines.

In the future, Hzymes biotech will always remember its original intention and persist in meticulous cultivation in the IVD field. It will adhere to independent research and development, accelerate the construction of a world-class specialty enzyme production platform, and achieve import substitution of core enzyme raw materials in the field of biomedicine in China. It will collaborate with leading biopharmaceutical companies to expand their global presence and contribute to the advancement of the industry.