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Updated: Dec 14, 2025

Precise Phage Mutagenesis with NgTET-Assisted CRISPR-Cas Systems
Published on: October 14, 2025
CRISPR-CasΦ from huge phages is a hypercompact genome editor
Patrick Pausch1,2, Basem Al-Shayeb1,3, Ezra Bisom-Rapp4
1Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA, USA.
Abstract:
CRISPR-Cas systems are found widely in prokaryotes, where they provide adaptive immunity against virus infection and plasmid transformation. We describe a minimal functional CRISPR-Cas system, comprising a single ~70-kilodalton protein, CasΦ, and a CRISPR array, encoded exclusively in the genomes of huge bacteriophages. CasΦ uses a single active site for both CRISPR RNA (crRNA) processing and crRNA-guided DNA cutting to target foreign nucleic acids. This hypercompact system is active in vitro and in human and plant cells with expanded target recognition capabilities relative to other CRISPR-Cas proteins. Useful for genome editing and DNA detection but with a molecular weight half that of Cas9 and Cas12a genome-editing enzymes, CasΦ offers advantages for cellular delivery that expand the genome editing toolbox.
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