Multiplex base editing to convert TAG into TAA codons in the human genome

Large-scale recoding has been shown to enable novel amino acids, biocontainment and viral resistance in bacteria only so far. Here we extend this to human cells demonstrating exceptional base editing to convert TAG to TAA for 33 essential genes via a single transfection, and examine base-editing genome-wide (observing ~ 40 C-to-T off-target events in essential gene exons). We also introduce GRIT, a computational tool for recoding. This demonstrates the feasibility of recoding, and multiplex editing in mammalian cells.