Moving UGI within Cas9 lowers unwanted DNA changes in cytosine base editors

Relocating the uracil DNA glycosylase inhibitor (UGI) within the Cas9 nickase architecture significantly reduces off-target activity while maintaining on-target editing efficiency.

• Cytosine base editors (CBEs) convert cytosine to thymine with the aid of uracil DNA glycosylase inhibitor (UGI) and Cas9 nickase.
• Classical CBEs demonstrate strong on-target activity but also exhibit considerable off-target effects associated with Cas9.
• Internal fusion of UGI within the nCas9 structure was implemented as a strategy to improve editing fidelity.
• This reorganization maintains comparable on-target editing efficiency while effectively minimizing off-target activity.
• The findings indicate a new engineering approach for developing high-fidelity CBEs suitable for genome editing.

Simplified