Recently, demands in RNA manufacturing for long-chain RNAs exceeding 100 nucleotides, such as single guide RNA (sgRNA) for genome editing, have been increasing. Generally, these types of RNA are longer than traditional chemically synthesized oligonucleotides.
Many challenges can be encountered during the chemical synthesis of long-chain RNA, such as the steric hindrance of the TBDMS (tert-butyldimethylsilyl) protecting group on RNA phosphoramidite monomers. In addition, in vitro transcription is widely used in long-chain RNA synthesis but cannot be utilized when any partial base modifications are required; for example, if uridine is to be replaced with pseudouridine, all uridines must be replaced.
To address these challenges, an efficient method was developed for manufacturing a high-quality long-chain RNA by enzymatic ligation from multiple chemically synthesized short-chain RNA fragments. The enzyme used was T4 RNA ligase 2, also known as dsRNA ligase. To ligate RNAs with this enzyme, it is necessary to form a nick-like structure at the joining site using complementary DNA splints. When two sequences of RNA are used, DNA splints that form complementary strands of several to 20 bases around the joining site are designed.
However, this method is not efficient for ligating fragments of three or more sequences. A highly efficient synthesis of long RNA was established through enzymatic ligation by designing short DNA splints to form complementary strands towards all short RNA fragments. This method was also applicable to the synthesis of 100-base-length RNAs with chemical modifications partially. Furthermore, a 560 base length mRNA encoding a protein was successfully synthesized, and a functional protein was synthesized by a cell-free translation system using this mRNA.
This solution for the production of long-stranded RNA allows for chemical modifications and is expected to lead to the development of nucleic acid drugs, which have previously not been possible as drug discovery targets due to chemical synthesis limitations.
Register for this webinar to learn how innovative long RNA manufacturing approaches can drive the development of next-generation RNA medicines.
Keywords: Basic Research, Bioprocess Development, CDMO/CMO, Drug Development, Drug Discovery, mRNA Technology, mRNA Therapeutics, Oligonucleotide Therapeutics, Oligonucleotides, Process Development, RNA, RNA Therapeutics