Programmed DNA destruction by miniature CRISPR-Cas14 enzymes

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• CRISPR-Cas systems confer microbial adaptive immunity against foreign nucleic acids.
• Existing CRISPR-Cas tools rely on large RNA-guided Cas proteins for specific DNA/RNA targeting.
• The size of Cas proteins was previously thought essential for their nuclease activity.

Purpose of the Study:

• To characterize a novel family of compact CRISPR-associated nucleases, termed Cas14, discovered in uncultivated archaea.
• To investigate the DNA-targeting and cleavage capabilities of Cas14 proteins.
• To explore the potential applications of Cas14 in genome editing and genetic analysis.

Main Methods:

• Bioinformatic analysis of metagenomic data to identify novel CRISPR-Cas systems.
• Biochemical characterization of Cas14 nucleases.
• Development and application of the Cas14-DETECTR assay for genotyping.

Main Results:

• Identification of Cas14, a family of small (400-700 amino acids) RNA-guided nucleases.
• Cas14 proteins exhibit targeted single-stranded DNA (ssDNA) cleavage activity without strict sequence limitations.
• Cas14 binding to a target ssDNA triggers collateral, non-specific ssDNA cleavage, enabling high-fidelity SNP genotyping (Cas14-DETECTR).

Conclusions:

• Cas14 represents a distinct class of CRISPR-associated enzymes with unique biochemical properties.
• The discovery of Cas14 expands the repertoire of CRISPR-based genome editing tools.
• Cas14-DETECTR offers a sensitive and specific method for single-nucleotide polymorphism genotyping.
• Metagenomic evidence suggests independent evolution of Cas14 systems, hinting at diverse origins of CRISPR immunity.