(A) Organization of cas genes in Pyrococcus furiosus. Cas genes are mainly distributed in two gene clusters in Pfu. Genes encoding predicted adaptation Cas proteins (Cas1, Cas2, Cas4, gray), crRNA biogenesis protein (Cas6, gray) and immune-effector modules: Type I-A (Csa, green), Type I-G (Cst, yellow), Type III-B (Cmr, blue) are labeled. Genes encoding Cas3 (light yellow) and Cas3′ (helicase or hel.), Cas3″ (nuclease or nuc.) (light green) correspond to their subtype association. Inverted Y indicates polyclonal antibodies were raised against the specified Csa, Cst, and Cmr proteins. (B) Western blotting of Pfu extract with Csa, Cst, and Cmr antibodies. The indicated antibodies detect a major band (asterisk) of the expected molecular weight for each antigen. The predicted molecular weights for each protein are Csa2 (37.4 kDa), Cas3″ (22.9 kDa), Cst2 (39.7 kDa), Cas5t (23.8 kDa), and Cmr2 (100.8 kDa).
