CasX Nickase Designs, Tans Cleavage Designs & Structure

Patent Status

Brief Description

Metagenomic analysis of microbial DNA from groundwater samples revealed a new protein, CasX, that prevented bacterial transformation by plasmid DNA when expressed with cognate crRNAs targeting the plasmid8. Sequence analysis of CasXrevealed no similarity to other CRISPR-Cas enzymes, except for the presence of a RuvC nuclease domain similar to that found in both Cas9 and Cas12a enzyme families as well as transposases and recombinases. The evolutionary ambiguity of CasX hinted at a distinct structure and mechanism for DNA targeting, but without reconstitution of a functional CasX enzyme it was not possible to determine its

mechanism of plasmid interference.

UC Berkeley inventors found variant CasX polypeptides that induce programmable, site-specific genome repression in E. coli and genome editing in human cells, distinct from Cas9 and Cas12a, which establishes this enzyme family as a third CRISPR-Cas system for genetic manipulation.

Suggested uses

• Genome editing
• Gene therapy
• Research tools
• Genomic imaging

Advantages

• Functions under different conditions than currently used CRISPR-Cas proteins
• Nucleotide sequence encoding the CasX is short, therefore especially useful when using a viral vector for deliver to cell