Fig. 2: Non-canonical small subunits (SSU) support R-loop formation.
From: Structural basis for assembly of non-canonical small subunits into type I-C Cascade
a Cas11 SSU are identical to the C terminus of Cas8c. b Canonical SSU found in type I-E, type III-A, type III-B, and the C-terminal domain of the type I-F large subunit aligned to the type I-C SSU. These SSUs are all helical bundles. c A channel of positively charged surface residues show Cas11c SSU likely accommodate the non-target strand during R-loop formation. d Putative Cas8c (purple) PAM site interacting residues (gray) determined by overlaying the dsDNA density (blue) from previous type I-C cryo-EM maps. e Cas8c (purple) and a homology model Cas3c (pink) show complementary surfaces for Cas3 docking. f Model of type I-C Cascade function.
