Engineered IscB-ωRNA system with a wider range of targets for base editing

Ten of 19 uncharacterized IscB proteins from uncultured microbes showed activity in mammalian cells.

• The narrow targeting scope of IscB systems necessitates the identification of additional IscBs that recognize different target-adjacent motifs (TAMs).
• IscB ortholog IscB.m16 was enhanced through protein and ωRNA engineering, expanding its TAM scope from MRNRAA to NNNGNA.
• A variant named IscB.m16* was created, demonstrating improved targeting capabilities.
• IscB.m16*-derived base editors showed robust base-editing efficiency in mammalian cells.
• These base editors effectively restored Duchenne muscular dystrophy proteins in diseased mice using single adeno-associated virus delivery.

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