Targeted DNA integration in human cells without double-strand breaks using CRISPR-associated transposases

Area of Science:

• Molecular Biology
• Genetics
• Biotechnology

Background:

• CRISPR-Cas9 genome editing induces double-strand breaks (DSBs), causing unwanted byproducts and reducing purity.
• A need exists for precise, efficient methods for large DNA sequence integration in eukaryotic genomes.

Purpose of the Study:

• To develop a novel genome engineering approach using CRISPR-associated transposases (CASTs) to enable programmable integration of large DNA sequences in human cells without generating DSBs.
• To optimize CAST system components and identify variants with enhanced integration efficiency.

Main Methods:

• Engineered the QCascade complex for improved DNA targeting and developed transcriptional activators via TnsC recruitment.
• Screened 15 bacterial CAST systems, identifying a highly active Pseudoalteromonas homolog.
• Investigated the role of bacterial ClpX in enhancing genomic integration efficiency.

Main Results:

• Demonstrated programmable integration of large DNA sequences in human cells using a CAST system, avoiding DSBs.
• Achieved significant improvements in integration efficiency through protein design, screening of homologs, and discovery of ClpX enhancement.
• Showcased the successful reconstitution of a complex bacterial multi-component machinery in human cells.

Conclusions:

• CRISPR-associated transposases (CASTs) offer a powerful, DSB-free alternative for large DNA integration in eukaryotic genome engineering.
• The identified CAST system and optimization strategies provide a robust foundation for future applications in synthetic biology and gene therapy.
• Bacterial ClpX significantly boosts genomic integration, highlighting its potential role in facilitating transposition processes.