CRISPR-Cas systems include Cas proteins, which are involved in acquisition, targeting and
cleavage of foreign DNA or RNA, and a guide RNA(s), which includes a segment that binds Cas proteins and a segment that binds to a target nucleic acid. For example, Class 2 CRISPR-Cas systems comprise a single Cas protein bound to a guide RNA, where the Cas protein binds to and cleaves a targeted nucleic acid. The programmable nature of these systems has facilitated their use as a versatile technology for use in modification of target nucleic acid.
UC Berkeley researchers have discovered a novel family of compact proteins (CasGamma) with a RuvC-like domain in the C-terminal end of the protein. These proteins are able to cleave nucleic acids. Viral and microbial (cellular) genomes were assembled from a variety of environmental and animal microbiome sources, and variants of a novel and previously unknown Cas protein family were uncovered from the sequences decoded. These CasGamma proteins utilize a guide RNA to perform RNA-directed cleavage of nucleic acids.