CRISPR-CasΦ from huge phages is a hypercompact genome editor.

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• CRISPR-Cas systems provide prokaryotic adaptive immunity against foreign nucleic acids.
• These systems are crucial for defense against viruses and plasmids.

Purpose of the Study:

• To describe a novel, minimal CRISPR-Cas system from huge bacteriophages.
• To characterize the function and capabilities of the CasΦ protein and its associated CRISPR array.

Main Methods:

• Bioinformatic analysis of bacteriophage genomes to identify the CasΦ system.
• In vitro biochemical assays to assess CasΦ's enzymatic activity (crRNA processing and DNA cleavage).
• Functional validation in human and plant cells to evaluate its genome editing and DNA detection potential.

Main Results:

• Identification of a hypercompact CRISPR-Cas system composed of a single protein, CasΦ, and a CRISPR array.
• CasΦ exhibits dual activity, performing both crRNA processing and crRNA-guided DNA cutting using a single active site.
• The system demonstrated activity in vitro and in eukaryotic cells (human and plant).
• CasΦ showed expanded target recognition capabilities compared to other CRISPR-Cas proteins.
• CasΦ's small size (half the molecular weight of Cas9 and Cas12a) facilitates cellular delivery.

Conclusions:

• CasΦ represents a novel, minimal CRISPR-Cas system with unique biochemical properties.
• Its compact nature and dual functionality make it a promising tool for advanced genome editing applications.
• CasΦ expands the CRISPR toolbox, offering advantages for cellular delivery and potentially broader target recognition in genome editing and DNA detection.