Genome editing in mammalian cells using the CRISPR type I-D nuclease

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• CRISPR-Cas systems have revolutionized genome engineering, with CRISPR-Cas9 and CRISPR-Cas12a widely adopted.
• CRISPR type I systems are the most abundant in bacteria but less developed for genome engineering.
• The mechanism of DNA degradation in CRISPR-Cas type I-D systems, lacking a canonical Cas3 nuclease, was previously unknown.

Purpose of the Study:

• To identify the functional nuclease responsible for DNA degradation in the CRISPR-Cas type I-D system.
• To investigate the potential of the CRISPR-Cas type I-D system for genome engineering applications in eukaryotic cells.

Main Methods:

• Biochemical assays to characterize the nuclease activity of Cas10d.
• Application of the CRISPR-Cas type I-D system in human cells for targeted mutagenesis.
• Analysis of DNA deletions and insertions generated by the type I-D system.

Main Results:

• Cas10d was identified as a functional nuclease in the type I-D system, analogous to Cas3 in other type I systems.
• The type I-D system successfully mediated targeted mutagenesis in human cells.
• Both long-range bi-directional deletions and short insertions/deletions were achieved using the type I-D system.

Conclusions:

• The CRISPR-Cas type I-D system utilizes Cas10d as its effector nuclease.
• This system represents a novel pathway for CRISPR-mediated genome engineering.
• The CRISPR-Cas type I-D system can be repurposed for genome editing in eukaryotic cells, expanding genome engineering tools.