# Improving the DNA specificity and applicability of base editing through protein engineering and protein delivery

Article · Rees HA, Komor AC, Yeh WH, Caetano-Lopes J, Warman M, Edge ASB, Liu DR

- Archive id: doi:10.1038/ncomms15790
- Published: 2017-06-06
- Venue: Nature communications
- DOI: https://doi.org/10.1038/ncomms15790
- PMID: 28585549
- PMCID: PMC5467206
- Citations: 355
- Source URL: https://doi.org/10.1038/ncomms15790
- PDF: https://europepmc.org/articles/PMC5467206/pdf
- Provenance: europepmc

## Abstract

We recently developed base editing, a genome-editing approach that enables the programmable conversion of one base pair into another without double-stranded DNA cleavage, excess stochastic insertions and deletions, or dependence on homology-directed repair. The application of base editing is limited by off-target activity and reliance on intracellular DNA delivery. Here we describe two advances that address these limitations. First, we greatly reduce off-target base editing by installing mutations into our third-generation base editor (BE3) to generate a high-fidelity base editor (HF-BE3). Next, we purify and deliver BE3 and HF-BE3 as ribonucleoprotein (RNP) complexes into mammalian cells, establishing DNA-free base editing. RNP delivery of BE3 confers higher specificity even than plasmid transfection of HF-BE3, while maintaining comparable on-target editing levels. Finally, we apply these advances to deliver BE3 RNPs into both zebrafish embryos and the inner ear of live mice to achieve specific, DNA-free base editing in vivo.

_Abstract reproduced under CC-BY (article license as recorded by Europe PMC; abstract reproduced unmodified apart from markup removal)._

Topics: [CRISPR & Gene-Editing Therapies](https://space-kitty.com/topics/gene-editing-therapies)

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