Co-transcriptional capping using an RNA capping enzyme-T7 RNA polymerase fusion protein

mRNA vaccines and therapeutics are highly effective and can be developed and manufactured with a relatively short lead time. Here we report an all-enzyme platform to generate capped synthetic RNA in a one-step process based on an RNA capping enzyme-T7 RNA polymerase fusion protein. Under standard in vitro transcription reaction conditions, the fusion protein, in conjunction with an RNA cap 2′-O-methyltransferase, can generate synthetic mRNA with up to 95% of Cap-1 incorporation, greatly simplifying mRNA manufacturing workflows.