Every mRNA vaccine or therapy ever approved — from COVID-19 shots to personalized cancer treatments — depends on a single bacterial enzyme discovered decades ago. If that enzymatic bottleneck can be improved, the downstream effects on manufacturing efficiency, product purity, and ultimately patient access could be substantial. That is precisely what this PNAS research proposes.
A research team characterizing bacteriophage diversity identified a naturally occurring homolog of the workhorse T7 RNA polymerase, sourced from Njord, a phage infecting Pseudomonas bacteria. Dubbed Njord RNAP, this cold-adapted enzyme evolved to function optimally at lower temperatures than the standard T7 enzyme. In head-to-head synthesis comparisons, Njord RNAP demonstrated improved performance in generating therapeutic mRNA, with the cold-adaptation profile offering potential advantages in reaction conditions that may reduce unwanted double-stranded RNA byproducts — a known immunogenicity concern in mRNA drug manufacturing. The enzyme retains promoter specificity compatible with existing T7-based transcription systems, suggesting it could slot into established production pipelines.
This finding sits at a critical juncture in mRNA medicine. T7 RNAP has been the field's unquestioned standard since the 1980s, and its limitations — including dsRNA contaminant generation and suboptimal kinetics at lower temperatures — have been engineering targets for years, largely through protein engineering of T7 itself. Discovering a natural cold-adapted homolog via phage genomics represents a bioprospecting approach that could circumvent the iterative mutagenesis strategies typically required. That said, the work at this stage appears to be biochemical and in vitro characterization rather than a validated GMP manufacturing demonstration. Scalability, regulatory acceptance of a novel polymerase, and long-term stability data remain open questions. Still, for a field hungry for manufacturing improvements to support personalized mRNA therapies at scale, this is a meaningfully promising lead — incremental in mechanism but potentially significant in practical impact.