This domain is found in Cas9 proteins which can be Staphylococcus aureus. Cas9 cleaves double-stranded DNA targets with a protospacer adjacent motif (PAM) and complementarity to the guide RNA. When this domain is combined with the C-terminal domain it is called the Pam-interacting (PI) domain. The Cas9 orthologs from different microbes have highly divergent sequences but their PI domains share a conserved core fold and recognize distinct PAM sequences [1].

1: Crystal Structure of the Minimal Cas9 from Campylobacter jejuni Reveals the Molecular Diversity in the CRISPR-Cas9 Systems. Yamada M, Watanabe Y, Gootenberg JS, Hirano H, Ran FA, Nakane T, Ishitani R, Zhang F, Nishimasu H, Nureki O; Mol Cell. 2017;65:1109-1121. PMID:28306506