Engineered Un1Cas12f1 with boosted gene-editing activity and expanded genomic coverage.

Compact programmable nucleases provide versatile genome editing tools with therapeutic potential, particularly when delivered via adeno-associated virus (AAV) vectors. However, their limited editing efficacy and stringent protospaceradjacent motif (PAM) requirements impose significant limitations in practical application. Here, we engineered MiniCasUltra, an optimized Un1Cas12f1 variant, through rational mutagenesis. MiniCasUltra exhibits sixfold higher editing activity than Un1Cas12f1, minimal off-target effects (on/off-target ratio > 10), and an expanded PAM preference (5'-WBTR). Using a single AAV vector encoding MiniCasUltra and two single-guide RNAs, we achieved simultaneous editing of two disease-causing genes (Pten and Fah) in mouse liver, with indel rates of 15.82% and 29.39%, respectively- significantly surpassing CasMINI V3.1 (3.45% and 10.98%). Furthermore, AAV delivery of MiniCasUltra targeting a noncanonical 5'-TCTG PAM site in human vascularendothelial growth factor A reduced choroidal neovascularization (CNV) lesions in a laser-induced CNV mouse model of neovascular age-related macular degeneration, a leading global cause of blindness. The broad and effective targeting capabilities of MiniCasUltra, coupled with its compact size, highlight its potential for in vivo genome editing and therapeutic interventions.