Comprehensive assessment of activity, specificity, and safety of hypercompact TnpB systems for gene editing

Abstract Background As the ancestor of CRISPR-Cas12 nucleases, TnpB represents the most compact gene editing tool currently available. Recent studies have identified multiple TnpB systems with gene editing activity in mammalian cells, and the potential of TnpB in treating diseases has been demonstrated in animal models. However, the editing characteristics of various TnpB systems, comparable to CRISPR tools, require more extensive investigation. Results Using a standardized evaluation framework, we conduct a thorough analysis of the editing properties of four TnpB variants alongside representative Cas12 and Cas9 tools applications. Overall, TnpBs exhibit intermediate editing activity and safety profiles among all tested systems, with ISYmu1 TnpB demonstrating a good performance in both editing activity and specificity. Considering its compact size, potent editing efficiency and high specificity, ISYmu1 TnpB represents a promising candidate for gene therapy. Conclusions By comprehensively analyzing genome editing outcomes, we characterize TnpB systems for genome editing and identify ISYmu1 TnpB as an optimal miniature RNA-guided genome editors with balanced performance, highlighting its potential for therapeutic applications.