Scientists continue to dig deeper into the Cas enzymes to further improve
CRISPR-based genome editing technologies. A new addition to these enzymes is
Cas14, which was discovered by researcher Lucas Harrington from University
of California Berkeley and colleagues.

In the study published in Science, the researchers describe the
characteristics of Cas14 in terms of size, gene architecture, phylogeny,
ability to associate with RNA components, ability to cleave DNA, and PAM
requirement. Results showed that Cas14 is a small enzyme, which is half the
size of previously known CRISPR RNA-guided enzymes. It was found to occur
exclusively in a group of symbiotic archaea, the members of which have small
genomes, and has similarities with previously characterized enzymes like
C2c10 and C2c9. Cas14 is also able to perform programmable RNA-guided
cleavage in the single-stranded DNA, making it the smallest known CRISPR
enzyme that can do so. It also does not require a PAM sequence, a
recognition site of most Cas enzymes, to function. Overall, the researchers
discover 38 CRISPR-Cas14 systems that they grouped into families, namely,
Cas14a to Cas14h. These systems may be used in studies that need targeting
of single-stranded viruses.



[www.ncbi.nlm.nih.gov]