Fig. 3

Modeling of the R2Bm RT domain and mapping of the proteolytic cleavages onto the RT model. a R2Bm RT model construction and confidence report from Phyre2. 5hhl: crystal structure of the RT domain of the group II intron encoded protein from Eubacterium rectale. 5g2xC: the maturase protein in the cryo-EM structures of a spliced Lactococcus lactis group II A intron RNP. 4i43B: the splicing factor Prp8 protein large domain crystal structure. 1khv: the crystal structure of rabbit hemorrhagic disease virus RNA-dependent RNA polymerase. b Ribbon model representation of R2Bm RT with several key regions highlighted. The pinky finger (RT0) is colored red, as is the middle finger of RT4. The region spanning from a portion of the −1 to RT0 is in yellow. This region includes a remnant of the −1 loop, the index finger α-helix, and the α-helix that traverses palm. The ring finger (RT1) is in blue, as is the RT2 α-helix. c Coulombic surface rendering of the R2Bm model. d Early proteolytic cleavage sites mapped onto the R2Bm RT model. Dark green coloring marks glutamic acid and aspartic acid residues that were cleaved. Pale green marks glutamic acid and aspartic acid residues that were not cleaved. Pink coloring marks lysine residues that were cleaved. Pale purple marks lysine residues that were not cleaved: See key in panel E. e Early plus later proteolytic cleavage sites mapped onto the R2Bm RT model. Markings are as in panel D