TALE-based C-to-T base editor for multiple homologous genes with flexible precision

Area of Science:

• Molecular Biology
• Genetics
• Plant Science

Background:

• CRISPR-Cas9 systems offer efficient C-to-T base editing but have limitations in targeting scope and off-target effects.
• Transcription activator-like effector (TALE)-based tools provide longer DNA recognition sequences, offering potential for enhanced base editing specificity.

Purpose of the Study:

• To develop a novel base editing system in Arabidopsis using cytidine deaminase fused to a TALE DNA-binding domain.
• To overcome the limitations of CRISPR-mediated base editing by expanding targeting scope and minimizing off-target mutations.

Main Methods:

• Fusion of cytidine deaminase to a TALE DNA-binding domain for targeted C-to-T base editing in Arabidopsis nuclear genes.
• Utilized a novel TALE-repeat unit capable of recognizing all four DNA bases, enabling targeting of variable codon positions.
• Employed a single TALE pair for simultaneous editing of multiple gene isoforms.

Main Results:

• Efficient and targeted C-to-T substitutions were achieved in Arabidopsis nuclear genes.
• The TALE-based system demonstrated an expanded targeting scope compared to previous methods.
• Suppression of off-target substitutions was observed, enhancing editing precision.
• Simultaneous base editing of multiple, highly similar gene isoforms was successfully demonstrated.

Conclusions:

• The developed TALE-cytidine deaminase fusion system provides an efficient and precise method for C-to-T base editing in Arabidopsis.
• This strategy enhances genome engineering capabilities by offering broader targeting and improved specificity, particularly for complex gene families.