Figure 3.

Restriction-modification (RM) and CRISPR-Cas system of cultivated Saccharibacteria strains. (A) Schematic diagram of TM7x (Type I/Type I), BB001 (Type III), and AC001 (Type II/Type III) RM systems. Hypothetical (H) and non-RM system proteins are shown in gray. The MTase (blue) and specificity subunit S (green) form an active multisubunit protein that methylates bipartite DNA recognition sequence. In the presence of REase subunit (orange), the complex can also act as an endonuclease. (B) Predicted recognition sequences of each RM system types shown in panel A. In each motif, base modifications that were detected during PacBio SMRT sequencing are shown in bold. (C) Gene cluster organization of PM004 CRISPR-Cas loci includes genes for the Cas9, Cas1, and Cas2 proteins with the CRISPR array.